bz wrote in
98.139:

Joy wrote in newsp.t8k1rkvqug52hc@user-
47b243c432.myhome.westell.com:

I am trying to make a beeper to plug into a sonic alert unit for a deaf
person.

I have a 12V DC transformer directly wired to a 3-20V DC beeping siren.
When the transformer is plugged in, the siren goes BEEP...BEEP...BEEP
as it should, but when the power is cut, the beeping fades out instead
of stopping immediately. BEEp...Beep...beee...

Is there a simple way to get the siren to silence as soon as the power
is cut?

Thanks so much!

Joy

one last try. Sorry. I missed seeing that you were using a 'DC
transformer'.

They have a capacitor built in that is holding a charge.

All you need to do is disconnect the siren from the power supply.
It should shut off immediately.

You should do this with a 110 vac relay.

Hook the coil of the relay in parallel with your power supply.
When the power comes on, you want the relay to close and hook the siren to
the power supply.
When the AC goes off, you want the relay to open and disconnect the siren
from the power supply.

The power supply will only use power when the beeper is activated. And you
won't be wasting power with a resistor and possibly damaging your power
supply.







--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap