piclist 2008\07\31\011821a >
Thread: voltage monitors
face BY : Forrest Christian email (remove spam text)

I'd switch the 2n2222 for a 2n7000. This will eliminate the B-E drain
through the 2n2222, and permit the use of a simple r/c network on the
gate of the 2n7000 to achieve the delay.   Plus, it should be more
efficient without the B-E current.

I'd probably start with the open drain output version of the supervisory
circuit, and connect it from the gate to ground.   Put a capacitor in
parallel (also from gate to ground).   Add a high-value pull up resistor
to +V.

That way, when it triggers, it will yank the gate to ground, turning off
the 2n7000.   When it "untriggers", the capacitor will slowly charge
through the pullup until it reaches the gate threshold, at which point
the 2n7000 will turn back on.    


Doug Metzler wrote:
{Quote hidden}

<48914AFC.9020603@imach.com> 7bit

In reply to: <017101c8f2c9$1ae93ae0$6901a8c0@bernese>
See also: www.piclist.com/techref/power.htm?key=voltage
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