In article , igor
wrote:

Go to your local auto store and get a remote door locking mechanism.
Then you can carry the "key" around in your pocket.

Dick


For an electronic approach, one idea that just came to mind would be to
use
a part from a doorbell. Maybe this part exists on its own somewhere, but
I
am thinking that when you press the doorbell button, on a ding-dong
version, it causes a striker (i.e., a pin) to be pulled back and then
when
you let go the pin springs forward. With a not-too-small battery you
could
power this thing and build it with parts from the cheapest doorbell from
the local big-box store plus some parts from Radio Shack. ("Where you
have
questions, we have answers, and the answers always are, 'Uhhh, I
duuno.'")
If you can find the same kind of pin part separately at an electronics
source it might well require less amperage, which would simplify things.