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OA47

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Joined: 11/04/2012
Location: Australia
Posts: 926

Posted: 06:34am 11 Nov 2023

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I am working on a Armmite F4 project and for portability reasons I would like to run on a battery so I thought about using a soft switch (momentary switch) to turn the unit on and it can be turned off via software using a button on the display or if a certain amount of time has elapsed without user input.

I hunted around the workshop for some components and this is basically the circuit that I came up with.

I built the circuit up on a piece of veroboard and mounted it in the case. I am using a cheap 2AH powerbank module to power the system.

This circuit may be usful to other members of the group.

Cheers
0A47

Mixtel90

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Joined: 05/10/2019
Location: United Kingdom
Posts: 6798

Posted: 08:21am 11 Nov 2023

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That's a neat way to do it. :)

I've used something like this Arduino one previously. (I've lost the original source). The P-channel mosfet is inconvenient though. The system of operation is similar except that an extra input signals that the user has pressed the button to switch off. Feed the D1 pullup from 3V3, of course.

Mick

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Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 4243

Posted: 08:54am 11 Nov 2023

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Hi OA47,

When the FET is off, there flows a current from P2 to P1 through an unpowered microsite chip, and a 5V regulator that does not have ground reference.
You have been lucky that it worked. Depending manufacturer and type of the voltage regulator, it might not work.
if you connect the cathode of the opto led to P3 it should work.

Volhout
Edited 2023-11-11 18:59 by Volhout

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Turbo46

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Joined: 24/12/2017
Location: Australia
Posts: 1611

Posted: 09:48am 11 Nov 2023

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This LINK shows something with a similar purpose.

Bill

Keep safe. Live long and prosper.

OA47

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Joined: 11/04/2012
Location: Australia
Posts: 926

Posted: 09:55am 11 Nov 2023

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Quote This LINK shows something with a similar purpose.

Thats what happens when you get old, you forget what you have done in the past.

0A47

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