edoleu
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Joined: Thu Jul 16, 2020 5:11 pm
Real Name: Ethan

Universal Security Instruments SA-1R Vehicle Siren Question

Thu Jul 16, 2020 5:19 pm

I just bought an old Universal Security Instruments SA-1R 12V siren at a garage sale. It has a small rectangular box mounted on the outside with three wires connected to it: Red, white and black. I took apart the motor housing and see that the red and white wires connect to the inside of the motor, the black wire is ground (as you may have guessed.)

Inside the externally-mounted rectangular box is a coil of very fine magnet wire and a contact mounted on a flexible metal strip. I don't know what this device is called, but I know that it sets up an oscillating magnetic field that causes the strip to vibrate rapidly and periodically make an electrical connection. The last time I saw something similar to this was in one of those fake-book pranks where it looks like a little book bound with metal foil. When you open the book you trigger a pendulum that swings back and forth through a coil of wire, generating a mild (but surprisingly strong) electrical shock.

Anyway, it seems that this is defective (a lot of rust flakes fell out when I opened it.)

My questions are: What is this part called? Is a replacement available?

Regards,
Ethan

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