About a year ago, I built a wireless flashing door bell
alert so my father could tell when somebody rang the bell while
he had headphones on while watching TV.

	It worked fine but he is moving to a retirement
community where the bell is physically different enough that my
circuit won't work there.

	On the old circuit, I had a current-limited optoisolater
at the output of a full-wave bridge
monitoring the signal across the chime which was a dirty 60-HZ
pulse normally and changed to 120 HZ when the button was pressed.

	The 12F675 then asserted 5 volts on Pin 5 which went
through a transistor sending power to an old 80's-vintage
cordless phone handset.

	The phone base station is used as the receiver and also
a power supply for the red flasher which is another PIC12F675
whose output pulses the base on a transistor that flashes a
12-volt LED light 5 times per second.

	The light flashes when the base station detects that the
handset came to life.

	In his new digs, the bell is an older-style
electromechanical chime which would be no problem except that I
don't have access to both sides of the bell transformer for
power there and the physical space is also smaller.

	A garage door opener would be perfect except I would
need to pop open the transmitter, solder the button contacts
closed and then find somewhere to stuff a diode bridge,
capacitor and regulator.

	If somebody already makes such a wireless relay link, I
would be a happy camper. If it was small enough, it could
probably fit inside the chime.

	I could ditch the old phone base station and use a wall
wart to power the flasher and receiver.

	If it turned out that the receiver is portable, it is
likely I could work around that as there is more physical space
on the flasher box.

	The only signal I need is a momentary closure or a
momentary shot of 5 volts when the bell rings.

	I even briefly entertained the thought of a microphone
and audio decoder circuit to "hear" the bell but it would be
easy to confuse and might false trigger from many sources.

	If somebody makes a contact closure wireless relay link
that runs on 8-24 volts AC, that's what I need.

	Thank you for any and all constructive ideas.

Martin McCormick
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