[Al Skierkiewicz]

Math,
Can you give us an idea of what size this device is? Old car alarms often used a siren type noise maker. They had a small electric motor at one end (about half as big as a CIM) usually painted red or black. The noise maker end looks like a chromed soup can with odd shaped slots cut into the circumference. The motor then spins up another cylinder inside the can also with odd shaped slots. The rushing air coupled with the slots produces a shrill noise much like an old fire engine or police car. Typical size was about 10" long and 2-3" in diameter. Some had a relay mounted on the outside and some just had a wire coming out one end. The other wire is tied internal to the metal case.