Artie Jones wrote:
> I need a cheap battery saver circuit. This is for legacy
> electronics-it shuts the appliance off if the user forgets to-which
> prevents the battery from draining if the user forgets to turn the
> power switch off.
>
> ...
>
> If anyone knows of a better circuit that does not require an
> additional switch (uses the stock power switch),

Of course there has to be something beyond the power switch, unless this
switch can be electrically tripped to off.  Something has to interrupt the
power if the users leaves the switch on.

> and needs to consume zero power when the auto shut off activates.

Learn how to write specs.  If you truly mean zero power, then forget about
it.  Quit now.  Go home.  Nothing draws zero power.  There is always some
leakage.  Real engineers understand there is a "good enough" level for
everything.  For starters, what is the self-discharge current of your
battery?

> The circuit can consume a few ma
> while the device is powered up. And, it should run on 9 volts

OK.

> (or higher) non regulated power.

Go home and write a real spec.  "Or higher" is totally rediculous.  How can
anyone advise you on a circuit when they have no idea whether it might need
to withstand 100V, 1000V, or more?

If it turns out the power source is one of those common 9V batteries with
clip on leads, then the answer might be a 10F200 with a P channel mosfet and
a few other parts.  However, it's pointless to get into this too far without
a spec.


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