"Peter Hucker" wrote...
Richard Crowley wrote:
"Peter Hucker" wrote ...
I have a device which makes a "ping" noise on a piezo tweeter
(one of those 10p sized things you get in wrist watches).

Is this (unidentified) "device" something with some power to it?
Or is it something like a wris****ch that runs on a coin cell
for a year?

It's got 5 volts into it at half an amp. It's a car satnav. If more
power is needed, I can always get 12V from the car, but it would
be neater not to.

Then you may be able to get away with something as simple
as tapping the signal that drives the piezo and using it to drive
a transistor which switches current to the LEDs. Depending
on how long the sound is vs. how long you want the LEDs
to flash, you may need to add an RC time constant to
"stretch" the length of the flash.