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[Reply #15 on:]

i asume you would like turn of the arduino to save battery power? otherwise i really see no point of shutting youre arduino down.

therefore this link is worth looking in to
http://arduino.cc/playground/Learning/ArduinoSleepCode

mabey worth a shot(although im not sure):
-remove youre diode and resistors and put a resistor between the emitter and the arduino
-use a darlington transistor

[Reply #16 on:]

You probably need an additional transistor to drive the base?

 

My LTSpice simulation shows that a pulse at the ON_Button switches Arduino on,
and a HIGH D2 would keep it on. D2 LOW switches it off.
 
 

[Reply #17 on:]

Thans pylon,
the idea to add an additional transistor has made me test the following schema:
(BTW, I've added an optocoupler rather than a transistor because I was afraid to fry pin2)



and it works!!!

Pressing the pushbutton, LED starts blinking: I then release the pushbutton and led flashes 10 times, than power goes down!

Thanks michael_x for your testing... I'm going to test the schema you have proposed.

Does anybody see any disadvantage in mine?

Thanks daatse for the reference to sleep code, but my goal is to switch completely the board off

[Reply #18 on:]

I'm looking to implement a self-power down function in my project too. This looks like a cheaper alternative to buying a $6 Pololu switch and paying another $5 in S/H. And I might just have an optocoupler lying around. Although I don't understand the need for it?

[Reply #19 on:]

You must have double posted, the mods don't like that at all? Anyway, I responded with one method I've used in your other post.

Lefty