Re: a circuit to switch a relay by a alarm clock

On Tue, 05 Apr 2005 18:34:04 +0000, Michael Black wrote:
> "Lord Garth" (LGarth@xxxxxxxxxxxx) writes:
>> "Thomas Vogel" <Tommi-Vogel@xxxxxx> wrote in message

>>> I want to construct a circuit which switch a relay by a alarm clock.
>>> Know anyone where I can find a plan in the internet or in a book or in
>>> a magazine?
>>>
>> You must define what signal the alarm clock produces before you can get
>> any useful responses. What is the output voltage? Is it a pulse or a
>> level? What are the specs of the relay you wish to use? Is the relay
>> supposed to stay energized until it is manually reset? Is the relay
>> circuit powered by a battery or a line source?
>>
>> Perhaps you mean you wish to build a digital alarm clock with a relay
>> output?
>>
> It sounds to me like he wants someone to explain how to do it, the
> problem being that the chances of two people having the same clock radio
> is pretty low.
>
> I did it to one, but it was really simple because I used a clock radio
> that was fairly old, and the clock was on a separate board from the
> actual radio. That made it real simple to find the wire that turned on
> the radio, and use it to turn on a relay.
....

I did this once with a "modern" digital alarm clock with a piezo beeper.
I just picked off the pulses to the beeper, and triggered a retriggerable
one-shot to turn on my large alarm, which was just a MVB and big speaker.
Actually, it was two MVBs, so I got a two-tone blare that really annoyed
the neighbors. ;-)

Cheers!
Rich

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