Circuit used in Dietz siren-light police-car system gives distinctive tones. Position t of S1 produces slow continuous rise and fall. Position 3 produces fast rising and falling tone. Position 2 rises slowly to full pitch when point 1 is grounded, then decays at same rate when point 1 is ungrounded. Position 3 gives most noticeable tone for break-
POLICE SIREN - schematic

in alarm on car. Terminal 1 goes to normally open door, hood, and other switches that complete circuit to ground when opened by intruder. Audio transistors and diode are general replacement types. -J. W. Crawford, The Ultimate Auto Alarm-Model II, CQ, Aug. 1971, p 54-57 and 96.

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