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Obtaining a switching signal from an alarm.

I've got an alarm clock which gives the usual 'beep beep' wake up call. I'd like to use it to switch a sound system on. The sound system is already switched via a low voltage relay, so I'd like some opinions on the most elegant way of doing this. I have my own ideas but wondered if I'm missing a better way. Direct connection to the clock isn't a problem.

--
*Some days you're the dog, some days the hydrant.

    Dave Plowman        dave@davenoise.co.uk           London SW
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Dave Plowman (News)
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Hi Dave

I guess that the beep tone will be generated by the micro in the thing, via the audio stage, so I would think that all you need to do is use the audio from across the speaker to drive a simple charge pump - one diode, one cap and maybe a resistor - to derive a DC level thereabouts equivalent to the peak value of the audio. Once you've got that, you can do pretty much whatever is needed to switch the sound system on i.e. via a buffer transistor, a momentary acting relay across the standby switch or self latching relay or whatever. If you put it all in the clock end, and use a relay to perform the actual switching, then there are no isolation problems either. On the other hand, if the bulk of it was at the hifi end, it might be easier to reset when you turn back off ??

Arfa

Reply to
Arfa Daily

Hm, simpler to use a cheap coffeepot with a timer. Remove the timer, put it in a small project case, and you have a perfectly good 15A clock timed relay :-)

Jammy

Reply to
ampdoc

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