In article m,
kens says...
On 3/27/2009 3:55 PM Tim spake thus:

In article m,
kens says...

(famous last words, "simple circuit" ...)

OK, so I'm trying to come up with a simple (maybe even elegant) solution
to a simple problem. Have an idea I want to run by y'all.

Function: person has a motion-detector light installed in their home.
They want a buzzer/bell/annunciator of some kind to go off *momentarily*
whenever the light is activated.

Here's my idea for the circuit:
http://www.geocities.com/bonezphoto/...e-shotBell.gif

OK, so a lot of issues here deal with the AC power being detected and
transferred to something useful. I did a simple data logger for my well
pump (URL: http://personal.nbnet.nb.ca/snowowl/DataRecorder.html), that
had to deal 220V being sensed. I used a cheap little cell phone / palm
pilot charger that was universal 110/220 50/60hz and wired it parallel
with the motor leads. This gave me a nice 5 volts when the power was
applied to the pump, so I could log it's on cycles. You still have to
wire it up the the light, so that's a danger here as well. Dealing with
AC mains wiring, there always a need for extra safety.

Thanks for your reply.

Unfortunately, your solution, while interesting, misses one of the
requirements of the whole deal: it needs to operate the
bell/chime/annunciator *momentarily*, not continuously.



Perhaps you are not inventive enough. My idea was to get a voltage low
enough to be safe. 5 volts could be used to fire a simple one-shot
circuit when the light comes on.

- Tim -