Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

--
This email has been checked for viruses by Avast antivirus software. www.avast.com

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more
positive. You need to exchange drain and source.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more positive. You need to exchange drain and source.

Cheers

Phil Hobbs

Belay that?I shouldn?t post after two G&Ts.

--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vnl0a$38eli$1@dont-email.me...

Basically, it doesn't work. It's cribbed off the internet. When I connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

--

A 3.3v variation on the circuit optimised by piglet some time ago may work better for that if pushbutton on/off is what you want.

Version 4.1
SHEET 1 2776 2100
WIRE -128 -128 -704 -128
WIRE 64 -128 -128 -128
WIRE 608 -128 64 -128
WIRE 704 -128 608 -128
WIRE 752 -128 704 -128
WIRE 912 -128 848 -128
WIRE 944 -128 912 -128
WIRE -128 -96 -128 -128
WIRE 64 -96 64 -128
WIRE 608 -96 608 -128
WIRE 608 16 608 -16
WIRE 704 16 608 16
WIRE 768 16 768 -80
WIRE 768 16 704 16
WIRE 608 48 608 16
WIRE -128 80 -128 -16
WIRE -64 80 -128 80
WIRE 336 80 16 80
WIRE 64 160 64 -16
WIRE 112 160 64 160
WIRE 224 160 192 160
WIRE 256 160 224 160
WIRE 336 160 336 80
WIRE 336 160 320 160
WIRE 352 160 336 160
WIRE 448 160 416 160
WIRE 480 160 448 160
WIRE 608 160 608 128
WIRE 608 160 560 160
WIRE 224 192 224 160
WIRE 448 192 448 160
WIRE 944 192 944 -128
WIRE -704 256 -704 -128
WIRE -304 288 -400 288
WIRE -224 288 -304 288
WIRE -128 288 -128 80
WIRE -128 288 -224 288
WIRE 224 288 448 192
WIRE 448 288 224 192
WIRE 224 304 224 288
WIRE 448 304 448 288
WIRE -400 352 -400 288
WIRE -448 368 -544 368
WIRE 64 384 64 160
WIRE 112 384 64 384
WIRE 224 384 224 368
WIRE 224 384 192 384
WIRE 448 384 448 368
WIRE 480 384 448 384
WIRE 608 384 608 160
WIRE 608 384 560 384
WIRE -448 416 -464 416
WIRE 64 432 64 384
WIRE 608 432 608 384
WIRE -544 448 -544 368
WIRE 224 480 448 384
WIRE 224 480 128 480
WIRE 448 480 224 384
WIRE 544 480 448 480
WIRE -128 496 -128 288
WIRE 224 528 224 480
WIRE 448 528 448 480
WIRE -704 624 -704 336
WIRE -544 624 -544 528
WIRE -544 624 -704 624
WIRE -464 624 -464 416
WIRE -464 624 -544 624
WIRE -400 624 -400 432
WIRE -400 624 -464 624
WIRE -128 624 -128 576
WIRE -128 624 -400 624
WIRE 64 624 64 528
WIRE 64 624 -128 624
WIRE 224 624 224 592
WIRE 224 624 64 624
WIRE 448 624 448 592
WIRE 448 624 224 624
WIRE 608 624 608 528
WIRE 608 624 448 624
WIRE 944 624 944 272
WIRE 944 624 608 624
WIRE -704 672 -704 624
WIRE -304 832 -304 288
WIRE -304 832 -416 832
WIRE -416 896 -416 832
WIRE -464 912 -480 912
WIRE -464 960 -560 960
WIRE -560 992 -560 960
WIRE -560 1104 -560 1072
WIRE -480 1104 -480 912
WIRE -480 1104 -560 1104
WIRE -416 1104 -416 976
WIRE -416 1104 -480 1104
WIRE -560 1152 -560 1104
WIRE -304 1184 -304 832
WIRE -352 1200 -368 1200
WIRE -352 1248 -448 1248
WIRE -448 1280 -448 1248
WIRE -448 1424 -448 1360
WIRE -368 1424 -368 1200
WIRE -368 1424 -448 1424
WIRE -304 1424 -304 1264
WIRE -304 1424 -368 1424
WIRE -448 1472 -448 1424
FLAG -704 672 0
FLAG -560 1152 0
FLAG -448 1472 0
FLAG -224 288 PUSHBUTTON
FLAG 704 16 gate
FLAG 704 -128 v48
FLAG 912 -128 sw
SYMBOL sw -400 448 M180
SYMATTR InstName S1
SYMATTR Value SWCH
SYMBOL voltage -544 432 R0
WINDOW 3 -366 360 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {1/4/F} 10u 10u {1/4/F} {1/F} 5)
SYMATTR InstName V1
SYMBOL voltage -704 240 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 3.3
SYMBOL sw -416 880 R0
SYMATTR InstName S2
SYMATTR Value SWCH
SYMBOL voltage -560 976 M0
WINDOW 3 43 129 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.245/F} 1u 1u 1m 2m 5)
SYMATTR InstName V3
SYMBOL sw -304 1168 R0
SYMATTR InstName S3
SYMATTR Value SWCH
SYMBOL voltage -448 1264 M0
WINDOW 3 59 141 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.501/F} 1u 1u 1m 2m 5)
SYMATTR InstName V4
SYMBOL npn 128 432 M0
SYMATTR InstName Q3
SYMATTR Value BC846B
SYMBOL res 48 -112 R0
SYMATTR InstName R11
SYMATTR Value 150k
SYMBOL npn 544 432 R0
SYMATTR InstName Q4
SYMATTR Value BC846B
SYMBOL res 208 368 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 470k
SYMBOL res 576 368 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R16
SYMATTR Value 470k
SYMBOL cap 320 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 100n
SYMBOL cap 416 176 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C2
SYMATTR Value 100n
SYMBOL res 592 -112 R0
SYMATTR InstName R17
SYMATTR Value 100k
SYMBOL res 592 32 R0
SYMATTR InstName R18
SYMATTR Value 10k
SYMBOL diode 208 368 M180
WINDOW 0 42 50 Left 2
WINDOW 3 -97 51 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL res 576 144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R20
SYMATTR Value 470k
SYMBOL diode 464 368 R180
WINDOW 0 42 50 Left 2
WINDOW 3 -96 52 Left 2
SYMATTR InstName D6
SYMATTR Value 1N4148
SYMBOL res 96 144 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R21
SYMATTR Value 470k
SYMBOL diode 208 592 M180
WINDOW 0 42 34 Left 2
WINDOW 3 -96 35 Left 2
SYMATTR InstName D8
SYMATTR Value 1N4148
SYMBOL diode 464 592 R180
WINDOW 0 43 30 Left 2
WINDOW 3 -98 34 Left 2
SYMATTR InstName D9
SYMATTR Value 1N4148
SYMBOL res -112 -112 M0
SYMATTR InstName R13
SYMATTR Value 470k
SYMBOL res -112 480 M0
SYMATTR InstName R22
SYMATTR Value 470k
SYMBOL res 32 64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R23
SYMATTR Value 220
SYMBOL pmos 848 -80 M270
WINDOW 0 -19 56 VLeft 2
WINDOW 3 76 99 VLeft 2
SYMATTR InstName M3
SYMATTR Value AO3423
SYMBOL res 928 176 R0
SYMATTR InstName RLOAD
SYMATTR Value 1k
TEXT -912 584 Left 2 !.tran 10 startup
TEXT -912 704 Left 2 !.param F=0.5
TEXT -912 744 Left 2 !.MODEL SWCH SW(Ron=.1 Roff=100Meg Vt=1)
TEXT 696 816 Left 2 ;EPW SED OCT 2025
TEXT 576 880 Left 2 ;INSPIRED BY EDWARD RAWDE
TEXT 544 944 Left 2 ;TOGGLE POWER ON PUSH BUTTON
TEXT -280 936 Left 2 ;BOUNCE ON MAKE
TEXT -240 1216 Left 2 ;BOUNCE ON BREAK



--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Wed, 3 Jun 2026 00:36:25 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more
positive. You need to exchange drain and source.

Cheers

Phil Hobbs

Belay that?I shouldn?t post after two G&Ts.

You were right the first time.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more positive. You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source
is whichever of the source and drain connections that happens to be more positive.

--
Bill Sloman, Sydney

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vnl0a$38eli$1@dont-email.me...

Basically, it doesn't work. It's cribbed off the internet. When I connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

Phil was right first time and it won't work without a load (R4 in the simulation below).

This site has various variations of it. http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/electronic-circuits/push-button-switch-turn-on/latching-toggle-power-switch

Version 4.1
SHEET 1 2776 2100
WIRE -1008 -480 -1168 -480
WIRE -896 -480 -1008 -480
WIRE -720 -480 -800 -480
WIRE -640 -480 -720 -480
WIRE -528 -480 -640 -480
WIRE -448 -480 -528 -480
WIRE -448 -448 -448 -480
WIRE -448 -320 -448 -368
WIRE -1008 -304 -1008 -480
WIRE -720 -304 -720 -480
WIRE -640 -288 -640 -480
WIRE -1008 -160 -1008 -224
WIRE -880 -160 -880 -432
WIRE -880 -160 -1008 -160
WIRE -1008 -96 -1008 -160
WIRE -880 48 -880 -160
WIRE -720 128 -720 -224
WIRE -720 128 -832 128
WIRE -640 128 -640 -224
WIRE -640 128 -720 128
WIRE -576 128 -640 128
WIRE -208 128 -576 128
WIRE -1168 256 -1168 -480
WIRE -1008 288 -1008 -16
WIRE -608 288 -1008 288
WIRE -560 288 -608 288
WIRE -512 288 -560 288
WIRE -608 352 -608 288
WIRE -720 368 -752 368
WIRE -656 368 -720 368
WIRE -1008 416 -1008 288
WIRE -656 416 -672 416
WIRE -752 448 -752 368
WIRE -1168 624 -1168 336
WIRE -1008 624 -1008 480
WIRE -1008 624 -1168 624
WIRE -880 624 -880 144
WIRE -880 624 -1008 624
WIRE -752 624 -752 528
WIRE -752 624 -880 624
WIRE -672 624 -672 416
WIRE -672 624 -752 624
WIRE -608 624 -608 432
WIRE -208 624 -208 128
WIRE -208 624 -608 624
WIRE -1168 672 -1168 624
WIRE -512 832 -512 288
WIRE -512 832 -624 832
WIRE -624 896 -624 832
WIRE -672 912 -688 912
WIRE -672 960 -768 960
WIRE -768 992 -768 960
WIRE -768 1104 -768 1072
WIRE -688 1104 -688 912
WIRE -688 1104 -768 1104
WIRE -624 1104 -624 976
WIRE -208 1104 -208 624
WIRE -208 1104 -624 1104
WIRE -768 1152 -768 1104
WIRE -512 1184 -512 832
WIRE -560 1200 -576 1200
WIRE -560 1248 -656 1248
WIRE -656 1280 -656 1248
WIRE -656 1424 -656 1360
WIRE -576 1424 -576 1200
WIRE -576 1424 -656 1424
WIRE -512 1424 -512 1264
WIRE -208 1424 -208 1104
WIRE -208 1424 -512 1424
WIRE -656 1472 -656 1424
FLAG -1168 672 0
FLAG -768 1152 0
FLAG -656 1472 0
FLAG -528 -480 sw
FLAG -448 -320 0
FLAG -576 128 button1
FLAG -560 288 button2
FLAG -720 368 pb
SYMBOL sw -608 448 M180
SYMATTR InstName S1
SYMATTR Value SWCH
SYMBOL voltage -752 432 R0
WINDOW 3 -366 360 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {1/4/F} 10u 10u {1/4/F} {1/F} 5)
SYMATTR InstName V1
SYMBOL voltage -1168 240 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 4
SYMBOL sw -624 880 R0
SYMATTR InstName S2
SYMATTR Value SWCH
SYMBOL voltage -768 976 M0
WINDOW 3 43 129 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.245/F} 1u 1u 1m 2m 5)
SYMATTR InstName V3
SYMBOL sw -512 1168 R0
SYMATTR InstName S3
SYMATTR Value SWCH
SYMBOL voltage -656 1264 M0
WINDOW 3 59 141 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.501/F} 1u 1u 1m 2m 5)
SYMATTR InstName V4
SYMBOL res -992 -320 M0
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res -992 -112 M0
SYMATTR InstName R2
SYMATTR Value 100k
SYMBOL cap -992 480 R180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C1
SYMATTR Value 1000n
SYMBOL nmos -832 48 M0
SYMATTR InstName TR2
SYMATTR Value IRF7309N
SYMBOL res -704 -320 M0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL pmos -800 -432 M270
WINDOW 0 73 1 VRight 2
WINDOW 3 -21 -49 VRight 2
SYMATTR InstName TR1
SYMATTR Value IRF7309P
SYMBOL schottky -656 -224 M180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D2
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -464 -464 R0
SYMATTR InstName R4
SYMATTR Value 1k
TEXT -1376 584 Left 2 !.tran 10 startup
TEXT -1120 704 Left 2 !.param F=0.5
TEXT -1120 744 Left 2 !.MODEL SWCH SW(Ron=.1 Roff=100Meg Vt=1)
TEXT -1160 -576 Left 2 ;TOGGLE POWER ON PUSH BUTTON
TEXT -488 936 Left 2 ;BOUNCE ON MAKE
TEXT -448 1216 Left 2 ;BOUNCE ON BREAK




--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

TTman <kraken.sankey@gmail.com>wrote:

Basically, it doesn't work. It's cribbed off the internet. When I

connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

If you are going to drive a microprocessor then let that do the on-off thing: Like this one:
https://panteltje.nl/pub/SWR_bridge_display_and_acquision_working_IMG_5018.JPG

press once -> on
press 3 times: off
If you program those PICs right then off-current is in the nano nano amp region.
Still working 100% on same Lipo after more than 10 years.

Circuit diagram:
https://panteltje.nl/pub/SWR_bridge_circuit_diagram_IMG_5053.JPG

Code for the PIC 18F14k22:
see line 1000:
https://panteltje.nl/pub/swrb-0.4.asm
PIC asm is fun :-)

https://panteltje.nl/pub/SWR_meter_IMG_6147.JPG


--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 06:53, Jan Panteltje wrote:

TTman <kraken.sankey@gmail.com>wrote:

Basically, it doesn't work. It's cribbed off the internet. When I

connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

If you are going to drive a microprocessor then let that do the on-off thing: Like this one:
https://panteltje.nl/pub/SWR_bridge_display_and_acquision_working_IMG_5018.JPG

press once -> on
press 3 times: off
If you program those PICs right then off-current is in the nano nano amp region.
Still working 100% on same Lipo after more than 10 years.

Circuit diagram:
https://panteltje.nl/pub/SWR_bridge_circuit_diagram_IMG_5053.JPG

Code for the PIC 18F14k22:
see line 1000:
https://panteltje.nl/pub/swrb-0.4.asm
PIC asm is fun :-)

https://panteltje.nl/pub/SWR_meter_IMG_6147.JPG

Yes, I already did that years ago with a tiny 25. But this is a
'discrete' design. No micro

--
This email has been checked for viruses by Avast antivirus software. www.avast.com

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 01:33, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more positive. You need to exchange drain and source.

Cheers

Phil Hobbs

But my 'load' side can never be more positive than the battery side...

--
This email has been checked for viruses by Avast antivirus software. www.avast.com

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the outputÿ ( TP5) is always on.
ÿ R3/D2 is supposed to guarantee a switch off when the switch is pressed >>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/
receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more
positive.ÿ You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source
is whichever of the source and drain connections that happens to be more positive.

So I need to flip source and drain? I'll try that...

--
This email has been checked for viruses by Avast antivirus software. www.avast.com

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 3:16 am, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the outputÿ ( TP5) is always on.
ÿ R3/D2 is supposed to guarantee a switch off when the switch is pressed >>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more
positive.ÿ You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source
is whichever of the source and drain connections that happens to be more positive.

Yes but you forgot the parasitic body diode.

piglet


--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 8:27 am, TTman wrote:

On 03/06/2026 01:33, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the outputÿ ( TP5) is always on.
ÿ R3/D2 is supposed to guarantee a switch off when the switch is pressed >>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more
positive.ÿ You need to exchange drain and source.

Cheers

Phil Hobbs

ÿBut my 'load' side can never be more positive than the battery side...

As Phil pointed out the parasitic body diode in the PFET was letting
current flow.

Also beware that to switch off reliably the R3 * cap 1uF time constanr
needs to be longer than the load capacitance TC takes to decay - so
either increase that cap or decrease the amount of capacitance across
the load.

piglet


--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 2:07 am, Edward Rawde wrote:

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vnl0a$38eli$1@dont-email.me...

Basically, it doesn't work. It's cribbed off the internet. When I connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

--

A 3.3v variation on the circuit optimised by piglet some time ago may work better for that if pushbutton on/off is what you want.

Version 4.1
SHEET 1 2776 2100
WIRE -128 -128 -704 -128
WIRE 64 -128 -128 -128
WIRE 608 -128 64 -128
WIRE 704 -128 608 -128
WIRE 752 -128 704 -128
WIRE 912 -128 848 -128
WIRE 944 -128 912 -128
WIRE -128 -96 -128 -128
WIRE 64 -96 64 -128
WIRE 608 -96 608 -128
WIRE 608 16 608 -16
WIRE 704 16 608 16
WIRE 768 16 768 -80
WIRE 768 16 704 16
WIRE 608 48 608 16
WIRE -128 80 -128 -16
WIRE -64 80 -128 80
WIRE 336 80 16 80
WIRE 64 160 64 -16
WIRE 112 160 64 160
WIRE 224 160 192 160
WIRE 256 160 224 160
WIRE 336 160 336 80
WIRE 336 160 320 160
WIRE 352 160 336 160
WIRE 448 160 416 160
WIRE 480 160 448 160
WIRE 608 160 608 128
WIRE 608 160 560 160
WIRE 224 192 224 160
WIRE 448 192 448 160
WIRE 944 192 944 -128
WIRE -704 256 -704 -128
WIRE -304 288 -400 288
WIRE -224 288 -304 288
WIRE -128 288 -128 80
WIRE -128 288 -224 288
WIRE 224 288 448 192
WIRE 448 288 224 192
WIRE 224 304 224 288
WIRE 448 304 448 288
WIRE -400 352 -400 288
WIRE -448 368 -544 368
WIRE 64 384 64 160
WIRE 112 384 64 384
WIRE 224 384 224 368
WIRE 224 384 192 384
WIRE 448 384 448 368
WIRE 480 384 448 384
WIRE 608 384 608 160
WIRE 608 384 560 384
WIRE -448 416 -464 416
WIRE 64 432 64 384
WIRE 608 432 608 384
WIRE -544 448 -544 368
WIRE 224 480 448 384
WIRE 224 480 128 480
WIRE 448 480 224 384
WIRE 544 480 448 480
WIRE -128 496 -128 288
WIRE 224 528 224 480
WIRE 448 528 448 480
WIRE -704 624 -704 336
WIRE -544 624 -544 528
WIRE -544 624 -704 624
WIRE -464 624 -464 416
WIRE -464 624 -544 624
WIRE -400 624 -400 432
WIRE -400 624 -464 624
WIRE -128 624 -128 576
WIRE -128 624 -400 624
WIRE 64 624 64 528
WIRE 64 624 -128 624
WIRE 224 624 224 592
WIRE 224 624 64 624
WIRE 448 624 448 592
WIRE 448 624 224 624
WIRE 608 624 608 528
WIRE 608 624 448 624
WIRE 944 624 944 272
WIRE 944 624 608 624
WIRE -704 672 -704 624
WIRE -304 832 -304 288
WIRE -304 832 -416 832
WIRE -416 896 -416 832
WIRE -464 912 -480 912
WIRE -464 960 -560 960
WIRE -560 992 -560 960
WIRE -560 1104 -560 1072
WIRE -480 1104 -480 912
WIRE -480 1104 -560 1104
WIRE -416 1104 -416 976
WIRE -416 1104 -480 1104
WIRE -560 1152 -560 1104
WIRE -304 1184 -304 832
WIRE -352 1200 -368 1200
WIRE -352 1248 -448 1248
WIRE -448 1280 -448 1248
WIRE -448 1424 -448 1360
WIRE -368 1424 -368 1200
WIRE -368 1424 -448 1424
WIRE -304 1424 -304 1264
WIRE -304 1424 -368 1424
WIRE -448 1472 -448 1424
FLAG -704 672 0
FLAG -560 1152 0
FLAG -448 1472 0
FLAG -224 288 PUSHBUTTON
FLAG 704 16 gate
FLAG 704 -128 v48
FLAG 912 -128 sw
SYMBOL sw -400 448 M180
SYMATTR InstName S1
SYMATTR Value SWCH
SYMBOL voltage -544 432 R0
WINDOW 3 -366 360 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {1/4/F} 10u 10u {1/4/F} {1/F} 5)
SYMATTR InstName V1
SYMBOL voltage -704 240 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 3.3
SYMBOL sw -416 880 R0
SYMATTR InstName S2
SYMATTR Value SWCH
SYMBOL voltage -560 976 M0
WINDOW 3 43 129 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.245/F} 1u 1u 1m 2m 5)
SYMATTR InstName V3
SYMBOL sw -304 1168 R0
SYMATTR InstName S3
SYMATTR Value SWCH
SYMBOL voltage -448 1264 M0
WINDOW 3 59 141 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.501/F} 1u 1u 1m 2m 5)
SYMATTR InstName V4
SYMBOL npn 128 432 M0
SYMATTR InstName Q3
SYMATTR Value BC846B
SYMBOL res 48 -112 R0
SYMATTR InstName R11
SYMATTR Value 150k
SYMBOL npn 544 432 R0
SYMATTR InstName Q4
SYMATTR Value BC846B
SYMBOL res 208 368 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 470k
SYMBOL res 576 368 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R16
SYMATTR Value 470k
SYMBOL cap 320 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 100n
SYMBOL cap 416 176 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C2
SYMATTR Value 100n
SYMBOL res 592 -112 R0
SYMATTR InstName R17
SYMATTR Value 100k
SYMBOL res 592 32 R0
SYMATTR InstName R18
SYMATTR Value 10k
SYMBOL diode 208 368 M180
WINDOW 0 42 50 Left 2
WINDOW 3 -97 51 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL res 576 144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R20
SYMATTR Value 470k
SYMBOL diode 464 368 R180
WINDOW 0 42 50 Left 2
WINDOW 3 -96 52 Left 2
SYMATTR InstName D6
SYMATTR Value 1N4148
SYMBOL res 96 144 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R21
SYMATTR Value 470k
SYMBOL diode 208 592 M180
WINDOW 0 42 34 Left 2
WINDOW 3 -96 35 Left 2
SYMATTR InstName D8
SYMATTR Value 1N4148
SYMBOL diode 464 592 R180
WINDOW 0 43 30 Left 2
WINDOW 3 -98 34 Left 2
SYMATTR InstName D9
SYMATTR Value 1N4148
SYMBOL res -112 -112 M0
SYMATTR InstName R13
SYMATTR Value 470k
SYMBOL res -112 480 M0
SYMATTR InstName R22
SYMATTR Value 470k
SYMBOL res 32 64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R23
SYMATTR Value 220
SYMBOL pmos 848 -80 M270
WINDOW 0 -19 56 VLeft 2
WINDOW 3 76 99 VLeft 2
SYMATTR InstName M3
SYMATTR Value AO3423
SYMBOL res 928 176 R0
SYMATTR InstName RLOAD
SYMATTR Value 1k
TEXT -912 584 Left 2 !.tran 10 startup
TEXT -912 704 Left 2 !.param F=0.5
TEXT -912 744 Left 2 !.MODEL SWCH SW(Ron=.1 Roff=100Meg Vt=1)
TEXT 696 816 Left 2 ;EPW SED OCT 2025
TEXT 576 880 Left 2 ;INSPIRED BY EDWARD RAWDE
TEXT 544 944 Left 2 ;TOGGLE POWER ON PUSH BUTTON
TEXT -280 936 Left 2 ;BOUNCE ON MAKE
TEXT -240 1216 Left 2 ;BOUNCE ON BREAK

Thanks, I have no recollection of that! I think unsuitable for battery
use as the standby current is high. Looks like an excercise in
Eccles-Jordan maximal complexity!

pigley


--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 4:18 am, Edward Rawde wrote:

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vnl0a$38eli$1@dont-email.me...

Basically, it doesn't work. It's cribbed off the internet. When I connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

Phil was right first time and it won't work without a load (R4 in the simulation below).

This site has various variations of it. http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/electronic-circuits/push-button-switch-turn-on/latching-toggle-power-switch

Version 4.1
SHEET 1 2776 2100
WIRE -1008 -480 -1168 -480
WIRE -896 -480 -1008 -480
WIRE -720 -480 -800 -480
WIRE -640 -480 -720 -480
WIRE -528 -480 -640 -480
WIRE -448 -480 -528 -480
WIRE -448 -448 -448 -480
WIRE -448 -320 -448 -368
WIRE -1008 -304 -1008 -480
WIRE -720 -304 -720 -480
WIRE -640 -288 -640 -480
WIRE -1008 -160 -1008 -224
WIRE -880 -160 -880 -432
WIRE -880 -160 -1008 -160
WIRE -1008 -96 -1008 -160
WIRE -880 48 -880 -160
WIRE -720 128 -720 -224
WIRE -720 128 -832 128
WIRE -640 128 -640 -224
WIRE -640 128 -720 128
WIRE -576 128 -640 128
WIRE -208 128 -576 128
WIRE -1168 256 -1168 -480
WIRE -1008 288 -1008 -16
WIRE -608 288 -1008 288
WIRE -560 288 -608 288
WIRE -512 288 -560 288
WIRE -608 352 -608 288
WIRE -720 368 -752 368
WIRE -656 368 -720 368
WIRE -1008 416 -1008 288
WIRE -656 416 -672 416
WIRE -752 448 -752 368
WIRE -1168 624 -1168 336
WIRE -1008 624 -1008 480
WIRE -1008 624 -1168 624
WIRE -880 624 -880 144
WIRE -880 624 -1008 624
WIRE -752 624 -752 528
WIRE -752 624 -880 624
WIRE -672 624 -672 416
WIRE -672 624 -752 624
WIRE -608 624 -608 432
WIRE -208 624 -208 128
WIRE -208 624 -608 624
WIRE -1168 672 -1168 624
WIRE -512 832 -512 288
WIRE -512 832 -624 832
WIRE -624 896 -624 832
WIRE -672 912 -688 912
WIRE -672 960 -768 960
WIRE -768 992 -768 960
WIRE -768 1104 -768 1072
WIRE -688 1104 -688 912
WIRE -688 1104 -768 1104
WIRE -624 1104 -624 976
WIRE -208 1104 -208 624
WIRE -208 1104 -624 1104
WIRE -768 1152 -768 1104
WIRE -512 1184 -512 832
WIRE -560 1200 -576 1200
WIRE -560 1248 -656 1248
WIRE -656 1280 -656 1248
WIRE -656 1424 -656 1360
WIRE -576 1424 -576 1200
WIRE -576 1424 -656 1424
WIRE -512 1424 -512 1264
WIRE -208 1424 -208 1104
WIRE -208 1424 -512 1424
WIRE -656 1472 -656 1424
FLAG -1168 672 0
FLAG -768 1152 0
FLAG -656 1472 0
FLAG -528 -480 sw
FLAG -448 -320 0
FLAG -576 128 button1
FLAG -560 288 button2
FLAG -720 368 pb
SYMBOL sw -608 448 M180
SYMATTR InstName S1
SYMATTR Value SWCH
SYMBOL voltage -752 432 R0
WINDOW 3 -366 360 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {1/4/F} 10u 10u {1/4/F} {1/F} 5)
SYMATTR InstName V1
SYMBOL voltage -1168 240 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 4
SYMBOL sw -624 880 R0
SYMATTR InstName S2
SYMATTR Value SWCH
SYMBOL voltage -768 976 M0
WINDOW 3 43 129 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.245/F} 1u 1u 1m 2m 5)
SYMATTR InstName V3
SYMBOL sw -512 1168 R0
SYMATTR InstName S3
SYMATTR Value SWCH
SYMBOL voltage -656 1264 M0
WINDOW 3 59 141 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.501/F} 1u 1u 1m 2m 5)
SYMATTR InstName V4
SYMBOL res -992 -320 M0
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res -992 -112 M0
SYMATTR InstName R2
SYMATTR Value 100k
SYMBOL cap -992 480 R180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C1
SYMATTR Value 1000n
SYMBOL nmos -832 48 M0
SYMATTR InstName TR2
SYMATTR Value IRF7309N
SYMBOL res -704 -320 M0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL pmos -800 -432 M270
WINDOW 0 73 1 VRight 2
WINDOW 3 -21 -49 VRight 2
SYMATTR InstName TR1
SYMATTR Value IRF7309P
SYMBOL schottky -656 -224 M180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D2
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -464 -464 R0
SYMATTR InstName R4
SYMATTR Value 1k
TEXT -1376 584 Left 2 !.tran 10 startup
TEXT -1120 704 Left 2 !.param F=0.5
TEXT -1120 744 Left 2 !.MODEL SWCH SW(Ron=.1 Roff=100Meg Vt=1)
TEXT -1160 -576 Left 2 ;TOGGLE POWER ON PUSH BUTTON
TEXT -488 936 Left 2 ;BOUNCE ON MAKE
TEXT -448 1216 Left 2 ;BOUNCE ON BREAK

Thanks, that mosaic industries website provoked some ideas, here is my
take on the "press-on, hold-off" circuit

<https://www.dropbox.com/scl/fi/sebg48vpqck1l67132w1m/PressON_HoldOFF.pdf?rlkey=3h7kz6rz9hgtwliwf119jgr1r&st=vh93zjoh&raw=1>

piglet



--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 3/06/2026 5:29 pm, TTman wrote:

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the outputÿ ( TP5) is always on.
ÿ R3/D2 is supposed to guarantee a switch off when the switch is
pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/
receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more
positive.ÿ You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source
is whichever of the source and drain connections that happens to be
more positive.

So I need to flip source and drain? I'll try that...

Don't bother. The FET decides which terminal is source or drain on the
basis of the voltage at each connection.

Even asymmetrical FETs work that way, but the performance can vary a bit
if the areas playing the role are bigger or smaller.

--
Bill Sloman, Sydney


--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10vp60g$3kkmu$1@dont-email.me...

On 3/06/2026 5:29 pm, TTman wrote:

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/ receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more
positive. You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source is whichever of the source and drain connections that
happens to be more positive.

So I need to flip source and drain? I'll try that...

Don't bother. The FET decides which terminal is source or drain on the basis of the voltage at each connection.

In that case please explain why reversing the source and drain in the simulation
I posted results in a circuit which no longer works.

Yes I know the explanation is obvious but you seem to be implying that the FET will work either way in that circuit. This is incorrect so telling the OP not to bother
doing that is nonsense.

Phil gave the correct solution .
The only other thing I would note is the way the load characteristics may affect
operation but this is explained on the web page I posted.

Even asymmetrical FETs work that way, but the performance can vary a bit if the areas playing the role are bigger or smaller.

--
Bill Sloman, Sydney

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Wed, 3 Jun 2026 11:17:09 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10vp60g$3kkmu$1@dont-email.me...

On 3/06/2026 5:29 pm, TTman wrote:

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/ receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more >>>>> positive. You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source is whichever of the source and drain connections that
happens to be more positive.

So I need to flip source and drain? I'll try that...

Don't bother. The FET decides which terminal is source or drain on the basis of the voltage at each connection.

In that case please explain why reversing the source and drain in the simulation
I posted results in a circuit which no longer works.

He forgot about substrate diodes.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"Jan Panteltje" <alien@comet.invalid> wrote in message news:10vofhf$3e4h1$1@dont-email.me...

TTman <kraken.sankey@gmail.com>wrote:

Basically, it doesn't work. It's cribbed off the internet. When I

connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

If you are going to drive a microprocessor then let that do the on-off thing: Like this one: https://panteltje.nl/pub/SWR_bridge_display_and_acquision_working_IMG_5018.JPG

You want to use a microprocessor for a push on/off power switch?
I'd have to admit I know people who might.
And if there's already a processor in the system then maybe sometimes it makes sense.
The usual process is:
1. Connect the switch to an input port with a pull up resistor if necessary.
2. Write software which logically will work perfectly.
3. Have trouble understanding what is going wrong.
4. Discover switch bounce.

press once -> on
press 3 times: off
If you program those PICs right then off-current is in the nano nano amp region.
Still working 100% on same Lipo after more than 10 years.

Circuit diagram: https://panteltje.nl/pub/SWR_bridge_circuit_diagram_IMG_5053.JPG

Code for the PIC 18F14k22:
see line 1000:
https://panteltje.nl/pub/swrb-0.4.asm
PIC asm is fun :-)

https://panteltje.nl/pub/SWR_meter_IMG_6147.JPG

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 4/06/2026 1:17 am, Edward Rawde wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10vp60g$3kkmu$1@dont-email.me...

On 3/06/2026 5:29 pm, TTman wrote:

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/ receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more >>>>> positive. You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source is whichever of the source and drain connections that
happens to be more positive.

So I need to flip source and drain? I'll try that...

Don't bother. The FET decides which terminal is source or drain on the basis of the voltage at each connection.

In that case please explain why reversing the source and drain in the simulation
I posted results in a circuit which no longer works.

The simulation uses a defective model for the FET

Yes I know the explanation is obvious but you seem to be implying that the FET
will work either way in that circuit. This is incorrect so telling the OP not to bother
doing that is nonsense.

Why do you think that it is incorrect? The simulation isn't evidence of
what the actual part will do.

Phil gave the correct solution .
The only other thing I would note is the way the load characteristics may affect
operation but this is explained on the web page I posted.

Even asymmetrical FETs work that way, but the performance can vary a bit if the areas playing the role are bigger or smaller.

--
Bill Sloman, Sydney



--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 4/06/2026 1:31 am, john larkin wrote:

On Wed, 3 Jun 2026 11:17:09 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10vp60g$3kkmu$1@dont-email.me...

On 3/06/2026 5:29 pm, TTman wrote:

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I >>>>>>> connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/ receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more >>>>>> positive. You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source is whichever of the source and drain connections that
happens to be more positive.

So I need to flip source and drain? I'll try that...

Don't bother. The FET decides which terminal is source or drain on the basis of the voltage at each connection.

In that case please explain why reversing the source and drain in the simulation
I posted results in a circuit which no longer works.

He forgot about substrate diodes.

Really?

The FET gate is a diode. If you reverse bias it hard enough you turn off
the FET channel. There aren't any "substrate diodes".

--
Bill Sloman, Sydney


--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10vpjhc$3ofnf$2@dont-email.me...

On 4/06/2026 1:17 am, Edward Rawde wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10vp60g$3kkmu$1@dont-email.me...

On 3/06/2026 5:29 pm, TTman wrote:

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I >>>>>>> connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/ receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more >>>>>> positive. You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source is whichever of the source and drain connections that
happens to be more positive.

So I need to flip source and drain? I'll try that...

Don't bother. The FET decides which terminal is source or drain on the basis of the voltage at each connection.

In that case please explain why reversing the source and drain in the simulation
I posted results in a circuit which no longer works.

The simulation uses a defective model for the FET

So that we all know what FET we're talking about,
please assume the P-channel one in this package.

https://www.infineon.com/dgdl/irf7309pbf-1.pdf

You might also want to explain why the symbol includes a diode and
what that will do to the circuit if you reverse the FET.

Yes I know the explanation is obvious but you seem to be implying that the FET
will work either way in that circuit. This is incorrect so telling the OP not to bother
doing that is nonsense.

Why do you think that it is incorrect? The simulation isn't evidence of what the actual part will do.

Phil gave the correct solution .
The only other thing I would note is the way the load characteristics may affect
operation but this is explained on the web page I posted.

Even asymmetrical FETs work that way, but the performance can vary a bit if the areas playing the role are bigger or smaller.

--
Bill Sloman, Sydney

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Bill Sloman <bill.sloman@ieee.org> wrote:

On 4/06/2026 1:31 am, john larkin wrote:

On Wed, 3 Jun 2026 11:17:09 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:10vp60g$3kkmu$1@dont-email.me...

On 3/06/2026 5:29 pm, TTman wrote:

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I >>>>>>>> connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/
receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0 >>>>>>>>

With a PFET, the source-drain diode conducts when the source is more >>>>>>> positive. You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the
source is whichever of the source and drain connections that
happens to be more positive.

So I need to flip source and drain? I'll try that...

Don't bother. The FET decides which terminal is source or drain on the >>>> basis of the voltage at each connection.

In that case please explain why reversing the source and drain in the simulation
I posted results in a circuit which no longer works.

He forgot about substrate diodes.

Really?

The FET gate is a diode. If you reverse bias it hard enough you turn off
the FET channel. There aren't any "substrate diodes".

It is not a jfet - insulated gate


--
piglet

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 6/2/2026 11:18 PM, Edward Rawde wrote:

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vnl0a$38eli$1@dont-email.me...

Basically, it doesn't work. It's cribbed off the internet. When I connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

Phil was right first time and it won't work without a load (R4 in the simulation below).

This site has various variations of it. http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/electronic-circuits/push-button-switch-turn-on/latching-toggle-power-switch

Nice - Thanks.
Ed

<snip>


--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Thu, 4 Jun 2026 02:12:59 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:

On 4/06/2026 1:31 am, john larkin wrote:

On Wed, 3 Jun 2026 11:17:09 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10vp60g$3kkmu$1@dont-email.me...

On 3/06/2026 5:29 pm, TTman wrote:

On 03/06/2026 03:16, Bill Sloman wrote:

On 3/06/2026 10:33 am, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I >>>>>>>> connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/ receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more >>>>>>> positive. You need to exchange drain and source.

Might be tricky. Most FETs are symmetrical, and for a P-FET the source is whichever of the source and drain connections that
happens to be more positive.

So I need to flip source and drain? I'll try that...

Don't bother. The FET decides which terminal is source or drain on the basis of the voltage at each connection.

In that case please explain why reversing the source and drain in the simulation
I posted results in a circuit which no longer works.

He forgot about substrate diodes.

Really?

The FET gate is a diode. If you reverse bias it hard enough you turn off
the FET channel. There aren't any "substrate diodes".

The OT uses enhancement mosfets, not depletion jfets. Mosfets have
insulated gates, occasionally with ESD protection zeners to the
source. I blew out a 2N7000 yesterday that doesn't have gate
protection.

Most all mosfets have a s-d substrate diode.

There are some small-signal mosfets that are symmetric, but they are
very rare. Those ususlly have a discrete substrate pin with substrate
diodes to both the source and drain.

Most semiconductors nowadays have diodes to the substrate from most
everything.

google mosfet substrate diode


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Tue, 2 Jun 2026 23:20:58 +0100, TTman <kraken.sankey@gmail.com>
wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

https://www.dropbox.com/scl/fi/h1g3j9azwpjo9b0gd7lwl/Push-Push.jpg?rlkey=24auhiblwxjqwtcphgtbstxhv&raw=1


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

So that we all know what FET we're talking about,
please assume the P-channel one in this package.

https://www.infineon.com/dgdl/irf7309pbf-1.pdf

You might also want to explain why the symbol includes a diode and
what that will do to the circuit if you reverse the FET.

Did you miss on my picture that the p fet is AO3047 and the n fet is
2n7002 ( both sot23).... I'm beginning to wonder if I need to use fets
with a low vGs The simulation works fine with the IRF dual part.

--
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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 12:24, piglet wrote:

On 03/06/2026 8:27 am, TTman wrote:

On 03/06/2026 01:33, Phil Hobbs wrote:

TTman <kraken.sankey@gmail.com> wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the outputÿ ( TP5) is always on.
ÿ R3/D2 is supposed to guarantee a switch off when the switch is
pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/
receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

With a PFET, the source-drain diode conducts when the source is more
positive.ÿ You need to exchange drain and source.

Cheers

Phil Hobbs

ÿÿBut my 'load' side can never be more positive than the battery side...

As Phil pointed out the parasitic body diode in the PFET was letting
current flow.

Also beware that to switch off reliably the R3 * cap 1uF time constanr
needs to be longer than the load capacitance TC takes to decay - so
either increase that cap or decrease the amount of capacitance across
the load.

piglet

Right now, there's nothing connected to the output, save a 1K resistor
to provide a bit of a load. D2/R3 is out nowm, as the battery will vever
gt 'disconnected' Apparently they are there for the case where the
supply is a PSU thatcan be switched off...

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 16:53, Edward Rawde wrote:

"Jan Panteltje" <alien@comet.invalid> wrote in message news:10vofhf$3e4h1$1@dont-email.me...

TTman <kraken.sankey@gmail.com>wrote:

Basically, it doesn't work. It's cribbed off the internet. When I

connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

If you are going to drive a microprocessor then let that do the on-off thing:
Like this one:
https://panteltje.nl/pub/SWR_bridge_display_and_acquision_working_IMG_5018.JPG

You want to use a microprocessor for a push on/off power switch?
I'd have to admit I know people who might.
And if there's already a processor in the system then maybe sometimes it makes sense.
The usual process is:
1. Connect the switch to an input port with a pull up resistor if necessary. 2. Write software which logically will work perfectly.
3. Have trouble understanding what is going wrong.
4. Discover switch bounce.

In the field that I'm looking at, all devices use a micro as it is the simplest solution to achieve the desired result. A polled push button
switch contact, whilst in deep sleep mode, is the obvious solution.The switches are invariable the 5mmx5mm tactile buttons that cost a couple
of pence ( compared to a toggle switch @œ1 plus.)
copule of options for me... try piglets on /hold off or consider a
latched push button.Try some low vGs fets... Downside is I already have
PCBs and I don't like to be beaten by something I don't really
understand- burried diodes? I spent 50+ years in the digital domain (
ever since RTL/DTL>TTL.) Analogue I just don't get :(

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vq5it$3vqp1$2@dont-email.me...

So that we all know what FET we're talking about,
please assume the P-channel one in this package.

https://www.infineon.com/dgdl/irf7309pbf-1.pdf

You might also want to explain why the symbol includes a diode and
what that will do to the circuit if you reverse the FET.

Did you miss on my picture that the p fet is AO3047

No but I couldn't find any such FET. Did you mean AO3407 ?

Changing TR2 to 2N7002 doesn't seem to make any difference
to the simulation.

and the n fet is 2n7002 ( both sot23).... I'm beginning to wonder if I need to use fets with a low vGs The simulation works fine
with the IRF dual part.

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 21:57, john larkin wrote:

On Tue, 2 Jun 2026 23:20:58 +0100, TTman <kraken.sankey@gmail.com>
wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

https://www.dropbox.com/scl/fi/h1g3j9azwpjo9b0gd7lwl/Push-Push.jpg?rlkey=24auhiblwxjqwtcphgtbstxhv&raw=1

Cool, but what happens if I push the switch and hold it down ?

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

TTman <kraken.sankey@gmail.com> wrote:

On 03/06/2026 21:57, john larkin wrote:

On Tue, 2 Jun 2026 23:20:58 +0100, TTman <kraken.sankey@gmail.com>
wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed
whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

https://www.dropbox.com/scl/fi/h1g3j9azwpjo9b0gd7lwl/Push-Push.jpg?rlkey=24auhiblwxjqwtcphgtbstxhv&raw=1

Cool, but what happens if I push the switch and hold it down ?

It is not a serious circuit! The floating gate will pickup all sorts of
static from people and charged objects just approaching the device without
even mechanically activating the switch. Hold a cellphone nearby and you
have wireless control!


--
piglet

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 22:35, Edward Rawde wrote:

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vq5it$3vqp1$2@dont-email.me...

So that we all know what FET we're talking about,
please assume the P-channel one in this package.

https://www.infineon.com/dgdl/irf7309pbf-1.pdf

You might also want to explain why the symbol includes a diode and
what that will do to the circuit if you reverse the FET.

Did you miss on my picture that the p fet is AO3047

No but I couldn't find any such FET. Did you mean AO3407 ?

Changing TR2 to 2N7002 doesn't seem to make any difference
to the simulation.

Yes, sorry, AO3407 :(

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 03/06/2026 22:50, piglet wrote:

TTman <kraken.sankey@gmail.com> wrote:

On 03/06/2026 21:57, john larkin wrote:

On Tue, 2 Jun 2026 23:20:58 +0100, TTman <kraken.sankey@gmail.com>
wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

https://www.dropbox.com/scl/fi/h1g3j9azwpjo9b0gd7lwl/Push-Push.jpg?rlkey=24auhiblwxjqwtcphgtbstxhv&raw=1

Cool, but what happens if I push the switch and hold it down ?

It is not a serious circuit! The floating gate will pickup all sorts of static from people and charged objects just approaching the device without even mechanically activating the switch. Hold a cellphone nearby and you
have wireless control!

Apart from that, it will auto switch between on and off.... I guess 100k
(?) source to gate will stop the 'noise'. Not sure I could tell someone
' don't hold the switch down too long'....LOL

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vqaf5$14pb$1@dont-email.me...

On 03/06/2026 22:35, Edward Rawde wrote:

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vq5it$3vqp1$2@dont-email.me...

So that we all know what FET we're talking about,
please assume the P-channel one in this package.

https://www.infineon.com/dgdl/irf7309pbf-1.pdf

You might also want to explain why the symbol includes a diode and
what that will do to the circuit if you reverse the FET.

Did you miss on my picture that the p fet is AO3047

No but I couldn't find any such FET. Did you mean AO3407 ?

Changing TR2 to 2N7002 doesn't seem to make any difference
to the simulation.

Yes, sorry, AO3407 :(

I can't find a model of AO3407 I would trust but if all you care about is
turn on voltage, and if you trust google AI (which I don't), then you
arrive at the following simulation which says it still works down to 2V input.

Version 4.1
SHEET 1 2776 2100
WIRE -1008 -480 -1168 -480
WIRE -896 -480 -1008 -480
WIRE -720 -480 -800 -480
WIRE -640 -480 -720 -480
WIRE -528 -480 -640 -480
WIRE -448 -480 -528 -480
WIRE -448 -448 -448 -480
WIRE -448 -320 -448 -368
WIRE -1008 -304 -1008 -480
WIRE -720 -304 -720 -480
WIRE -640 -288 -640 -480
WIRE -1008 -160 -1008 -224
WIRE -880 -160 -880 -432
WIRE -880 -160 -1008 -160
WIRE -1008 -96 -1008 -160
WIRE -880 48 -880 -160
WIRE -720 128 -720 -224
WIRE -720 128 -832 128
WIRE -640 128 -640 -224
WIRE -640 128 -720 128
WIRE -576 128 -640 128
WIRE -208 128 -576 128
WIRE -1168 256 -1168 -480
WIRE -1008 288 -1008 -16
WIRE -608 288 -1008 288
WIRE -560 288 -608 288
WIRE -512 288 -560 288
WIRE -608 352 -608 288
WIRE -720 368 -752 368
WIRE -656 368 -720 368
WIRE -1008 416 -1008 288
WIRE -656 416 -672 416
WIRE -752 448 -752 368
WIRE -1168 624 -1168 336
WIRE -1008 624 -1008 480
WIRE -1008 624 -1168 624
WIRE -880 624 -880 144
WIRE -880 624 -1008 624
WIRE -752 624 -752 528
WIRE -752 624 -880 624
WIRE -672 624 -672 416
WIRE -672 624 -752 624
WIRE -608 624 -608 432
WIRE -208 624 -208 128
WIRE -208 624 -608 624
WIRE -1168 672 -1168 624
WIRE -512 832 -512 288
WIRE -512 832 -624 832
WIRE -624 896 -624 832
WIRE -672 912 -688 912
WIRE -672 960 -768 960
WIRE -768 992 -768 960
WIRE -768 1104 -768 1072
WIRE -688 1104 -688 912
WIRE -688 1104 -768 1104
WIRE -624 1104 -624 976
WIRE -208 1104 -208 624
WIRE -208 1104 -624 1104
WIRE -768 1152 -768 1104
WIRE -512 1184 -512 832
WIRE -560 1200 -576 1200
WIRE -560 1248 -656 1248
WIRE -656 1280 -656 1248
WIRE -656 1424 -656 1360
WIRE -576 1424 -576 1200
WIRE -576 1424 -656 1424
WIRE -512 1424 -512 1264
WIRE -208 1424 -208 1104
WIRE -208 1424 -512 1424
WIRE -656 1472 -656 1424
FLAG -1168 672 0
FLAG -768 1152 0
FLAG -656 1472 0
FLAG -528 -480 sw
FLAG -448 -320 0
FLAG -576 128 button1
FLAG -560 288 button2
FLAG -720 368 pb
SYMBOL sw -608 448 M180
SYMATTR InstName S1
SYMATTR Value SWCH
SYMBOL voltage -752 432 R0
WINDOW 3 -366 360 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {1/4/F} 10u 10u {1/4/F} {1/F} 5)
SYMATTR InstName V1
SYMBOL voltage -1168 240 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 4
SYMBOL sw -624 880 R0
SYMATTR InstName S2
SYMATTR Value SWCH
SYMBOL voltage -768 976 M0
WINDOW 3 43 129 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.245/F} 1u 1u 1m 2m 5)
SYMATTR InstName V3
SYMBOL sw -512 1168 R0
SYMATTR InstName S3
SYMATTR Value SWCH
SYMBOL voltage -656 1264 M0
WINDOW 3 59 141 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 2 {.501/F} 1u 1u 1m 2m 5)
SYMATTR InstName V4
SYMBOL res -992 -320 M0
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res -992 -112 M0
SYMATTR InstName R2
SYMATTR Value 100k
SYMBOL cap -992 480 R180
WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
SYMATTR InstName C1
SYMATTR Value 1000n
SYMBOL nmos -832 48 M0
SYMATTR InstName TR2
SYMATTR Value 2N7002
SYMBOL res -704 -320 M0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL pmos -800 -432 M270
WINDOW 0 73 1 VRight 2
WINDOW 3 -21 -49 VRight 2
SYMATTR InstName TR1
SYMATTR Value AO3407
SYMBOL schottky -656 -224 M180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D2
SYMATTR Value BAT54
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -464 -464 R0
SYMATTR InstName R4
SYMATTR Value 1k
TEXT -1376 584 Left 2 !.tran 10 startup
TEXT -1120 704 Left 2 !.param F=0.5
TEXT -1120 744 Left 2 !.MODEL SWCH SW(Ron=.1 Roff=100Meg Vt=1)
TEXT -1168 -552 Left 2 ;TOGGLE POWER ON PUSH BUTTON
TEXT -488 936 Left 2 ;BOUNCE ON MAKE
TEXT -448 1216 Left 2 ;BOUNCE ON BREAK
TEXT -520 -136 Left 2 !.model AO3407 PMOS(Level=3 Vto=-1.9\n+ Kp=15.5 Rs=35m Rd=15m Cgso=1.1n\n+ Cgdo=0.15n CBD=1.1n Is=1e-12
Vds=-30)



--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vq6h0$3vqp1$4@dont-email.me...

On 03/06/2026 16:53, Edward Rawde wrote:

"Jan Panteltje" <alien@comet.invalid> wrote in message news:10vofhf$3e4h1$1@dont-email.me...

TTman <kraken.sankey@gmail.com>wrote:

Basically, it doesn't work. It's cribbed off the internet. When I

connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

If you are going to drive a microprocessor then let that do the on-off thing:
Like this one:
https://panteltje.nl/pub/SWR_bridge_display_and_acquision_working_IMG_5018.JPG

You want to use a microprocessor for a push on/off power switch?
I'd have to admit I know people who might.
And if there's already a processor in the system then maybe sometimes it makes sense.
The usual process is:
1. Connect the switch to an input port with a pull up resistor if necessary. >> 2. Write software which logically will work perfectly.
3. Have trouble understanding what is going wrong.
4. Discover switch bounce.

In the field that I'm looking at, all devices use a micro as it is the simplest solution to achieve the desired result. A polled
push button switch contact, whilst in deep sleep mode, is the obvious solution.The switches are invariable the 5mmx5mm tactile
buttons that cost a couple of pence ( compared to a toggle switch @?1 plus.)
copule of options for me... try piglets on /hold off or consider a latched push button.Try some low vGs fets... Downside is I
already have PCBs

If you already have PCBs and if you've managed to reverse D and S for the AO3407
(which will be tricky because you can't just solder it on upside down) then there
is likely and error somewhere else.

and I don't like to be beaten by something I don't really understand- burried diodes? I spent 50+ years in the digital domain (
ever since RTL/DTL>TTL.) Analogue I just don't get :(

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vq5it$3vqp1$2@dont-email.me...

So that we all know what FET we're talking about,
please assume the P-channel one in this package.

https://www.infineon.com/dgdl/irf7309pbf-1.pdf

You might also want to explain why the symbol includes a diode and
what that will do to the circuit if you reverse the FET.

Did you miss on my picture that the p fet is AO3047 and the n fet is 2n7002 ( both sot23).... I'm beginning to wonder if I need to
use fets with a low vGs The simulation works fine with the IRF dual part.

As well as the reversed D and S, the capacitor C1 look like it could be
either short or open circuit. If that was carried to the layout then in
either case the output won't turn on.

As far as I can tell the simulation works fine with a 2N7002 for TR2
and an AO3407 model with Vth = -1.9V

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Wed, 3 Jun 2026 22:38:43 +0100, TTman <kraken.sankey@gmail.com>
wrote:

On 03/06/2026 21:57, john larkin wrote:

On Tue, 2 Jun 2026 23:20:58 +0100, TTman <kraken.sankey@gmail.com>
wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone

https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

https://www.dropbox.com/scl/fi/h1g3j9azwpjo9b0gd7lwl/Push-Push.jpg?rlkey=24auhiblwxjqwtcphgtbstxhv&raw=1

Cool, but what happens if I push the switch and hold it down ?

Half bright. That's the dimmer function.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Wed, 3 Jun 2026 21:50:04 -0000 (UTC), piglet
<erichpwagner@hotmail.com> wrote:

TTman <kraken.sankey@gmail.com> wrote:

On 03/06/2026 21:57, john larkin wrote:

On Tue, 2 Jun 2026 23:20:58 +0100, TTman <kraken.sankey@gmail.com>
wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

https://www.dropbox.com/scl/fi/h1g3j9azwpjo9b0gd7lwl/Push-Push.jpg?rlkey=24auhiblwxjqwtcphgtbstxhv&raw=1

Cool, but what happens if I push the switch and hold it down ?

It is not a serious circuit! The floating gate will pickup all sorts of >static from people and charged objects just approaching the device without >even mechanically activating the switch. Hold a cellphone nearby and you
have wireless control!

I have one running in my office. Works fine.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 04/06/2026 02:22, Edward Rawde wrote:

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vq5it$3vqp1$2@dont-email.me...

So that we all know what FET we're talking about,
please assume the P-channel one in this package.

https://www.infineon.com/dgdl/irf7309pbf-1.pdf

You might also want to explain why the symbol includes a diode and
what that will do to the circuit if you reverse the FET.

Did you miss on my picture that the p fet is AO3047 and the n fet is 2n7002 ( both sot23).... I'm beginning to wonder if I need to
use fets with a low vGs The simulation works fine with the IRF dual part.

As well as the reversed D and S, the capacitor C1 look like it could be either short or open circuit. If that was carried to the layout then in either case the output won't turn on.

As far as I can tell the simulation works fine with a 2N7002 for TR2
and an AO3407 model with Vth = -1.9V

I'll check that and let you know. Thx for confirming sim result !

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

As well as the reversed D and S, the capacitor C1 look like it could be
either short or open circuit. If that was carried to the layout then in
either case the output won't turn on.

As far as I can tell the simulation works fine with a 2N7002 for TR2
and an AO3407 model with Vth = -1.9V

I'll check that and let you know. Thx for confirming sim result !

It's all working as it should now. Couple of track cuts and links to
sort the P fet. It won't work with zero load on the O/P. 10K works
fine.In the full circuit, load is at least 5mA from the receiver module.
I had one other P fet in the circuit and I had to switch D-S on that.
Worked fine when done.
Thanks evryone for your help- especially ED for the LT sim confirmation
that boosted my confidence no end..
Well happy.


--
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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Wed, 3 Jun 2026 23:42:08 +0100, TTman <kraken.sankey@gmail.com>
wrote:

On 03/06/2026 22:50, piglet wrote:

TTman <kraken.sankey@gmail.com> wrote:

On 03/06/2026 21:57, john larkin wrote:

On Tue, 2 Jun 2026 23:20:58 +0100, TTman <kraken.sankey@gmail.com>
wrote:

Basically, it doesn't work. It's cribbed off the internet. When I
connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

https://www.dropbox.com/scl/fi/h1g3j9azwpjo9b0gd7lwl/Push-Push.jpg?rlkey=24auhiblwxjqwtcphgtbstxhv&raw=1

Cool, but what happens if I push the switch and hold it down ?

It is not a serious circuit! The floating gate will pickup all sorts of
static from people and charged objects just approaching the device without >> even mechanically activating the switch. Hold a cellphone nearby and you
have wireless control!

Apart from that, it will auto switch between on and off.... I guess 100k
(?) source to gate will stop the 'noise'. Not sure I could tell someone
' don't hold the switch down too long'....LOL

A resistor source to gate will always turn it off.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 04/06/2026 01:45, Edward Rawde wrote:

"TTman" <kraken.sankey@gmail.com> wrote in message news:10vq6h0$3vqp1$4@dont-email.me...

On 03/06/2026 16:53, Edward Rawde wrote:

"Jan Panteltje" <alien@comet.invalid> wrote in message news:10vofhf$3e4h1$1@dont-email.me...

TTman <kraken.sankey@gmail.com>wrote:

Basically, it doesn't work. It's cribbed off the internet. When I

connect a battery,( lipo) the output ( TP5) is always on.
R3/D2 is supposed to guarantee a switch off when the switch is pressed >>>>> whilst the circuit is on.
This is a dropbox link but I'm not sure if it can be accessed by anyone >>>>>
https://www.dropbox.com/scl/fi/7l0abaly8cyduatirbyc6/receiverswitch.jpg?rlkey=o7dilm4mopzcb4m4mtxmjfxfo&st=yqz4i6i9&dl=0

If you are going to drive a microprocessor then let that do the on-off thing:
Like this one:
https://panteltje.nl/pub/SWR_bridge_display_and_acquision_working_IMG_5018.JPG

You want to use a microprocessor for a push on/off power switch?
I'd have to admit I know people who might.
And if there's already a processor in the system then maybe sometimes it makes sense.
The usual process is:
1. Connect the switch to an input port with a pull up resistor if necessary.
2. Write software which logically will work perfectly.
3. Have trouble understanding what is going wrong.
4. Discover switch bounce.

In the field that I'm looking at, all devices use a micro as it is the simplest solution to achieve the desired result. A polled
push button switch contact, whilst in deep sleep mode, is the obvious solution.The switches are invariable the 5mmx5mm tactile
buttons that cost a couple of pence ( compared to a toggle switch @?1 plus.) >> copule of options for me... try piglets on /hold off or consider a latched push button.Try some low vGs fets... Downside is I
already have PCBs

If you already have PCBs and if you've managed to reverse D and S for the AO3407
(which will be tricky because you can't just solder it on upside down) then there
is likely and error somewhere else.

All sorted, track cuts, links,all working. Definitely needs a load on
the o/p to function. 10K worked fine. Plenty of load in the overall
design (>5mA +)

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--- PyGate Linux v1.5.15
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

With the exception of PFET wiring error, just exchange D-S to fix it, that's a pretty good circuit. TR1 /TR2 form a classic bistable latch, meaning turn it on and it stays on, and turn it off and it stays off. The actuating signal via SW-PB is momentary. Taking ON to mean TR1 is on and passing Vbatt to the output, the state is latched by the Vbatt output through R3 to the gate of TR2 turning it on and pulling the gate of TR1 to GND, reinforcing the ON condition.
Cap is discharged to 0V in the ON state through R2 and the drain of TR2. So pressing SW-PB during the ON state causes the gate of TR2 to be discharged into the much larger 1u Cap. TR2 then turns off instantly, causing the gate of TR1 to be charged high through R1, turning TR1 off. Since Vbatt is removed from the output, the latching voltage through R3 is removed, and the gate of TR2 stays discharged, latching TR2/TR1 off. If you continue to hold the press on SW-PB, the gate of TR2 will be charged through R2 and R3/D2 to the output. The circuit will eventually go out of the OFF state and back to the ON state if Cap is allowed to charge to TR2 gate threshold. To prevent this, a loaded output limiting the Cap voltage to 0.2V will work. The series resistance is approximately R2= 100k, so Rmax, load= 0.2V/(Vbatt/100k)= 4.7kR should work. You can eliminate that 3/4 ma static loading in the ON state with another momentary, ganged to SW-PB. Or you can migrate to LVMOS logic for a bistable controlling the single AO3047, and have zero static loading in either state.

--
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--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)