Built from whatever was lying around
December 11, 2011
I was cleaning up and found this still screwed to the wall in my basement. I don’t remember building it but from its purpose it probably dates from around 1985 and was slapped together out of miscellaneous recycled parts plus one item from Radio Shack.
Any guesses what it was for?
2 readers have called it - it's an alarm. I thought the battery corrosion was pretty.
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I’m going to take a stab at it. Is it a low temperature alarm? I don’t recognize the Radio Shack (Archer) part on the board off hand, but it’s probably a little relay.
Humidity/moisture detection? Maybe. Or CO? I sorta remember you putting something together for the basement, but damned if I remember more than that!
I have got to start putting up harder questions. You both got it – it’s an alarm.
When an external circuit is energized, the relay closes sending 3 volts to the little buzzer at left. The external circuit is AC so there’s a diode to make sure the relay gets pulled in the right direction. The pot trims volume of the buzzer. Circuit in question is a doorbell; as my hearing got worse I couldn’t hear the doorbell upstairs.
Snapped the picture before throwing the thing away because I thought the battery corrosion was rather pretty.
Ah … the darkroom (or listening to jazz on GLT) days.
Actually the station I listened to most in the darkroom was WILL-AM 580. Some fascinating guests on that station.
I listened to that a lot, too. But our Saturday (?) nights down there listening to jazz changed my musical tastes.
I have something similar : a piezobuzzer & battery on a piece of veroboard at the lowest point in the cellar.
That way, if the washing machine leaks or other flooding starts, I get an acoustic warning. But mine just goes to 11, there’s no volume pot
I figgered alarm as soom as I saw the buzzer. Figured maybe a hi water alarm, too. Friend of mine with hearing loss cobbled up something similar for his car because he couldn’t hear the turn signal clicker.