buzzer only beep once

Posted on Feb 7, 2014

basically i have what is known as a bite alarm (for fishing). normally bite alarms beep as the fishing line passes over a wheel which usually has notches in it to allow some sort of optical switching making it go beep-beep-beep until the wheel stops. however i have been given some particularly cheap alarms which quite often get stuck with the buzz

buzzer only beep once
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er constantly on and i have to physically move the wheel to silence the buzzer. I have discovered that this alarm uses a reed switch with magnets on the wheel, so if the magnet gets stuck next to the reed switch the buzzer sounds constantly. I have connected everything as it is on the diagram and with the added notes in your last post to no avail, the only difference being that i am using a bc548.

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