The device is useful for a model fire truck and a guard system. The intervals between the signals and their duration is controlled by changing values of electrolytic capacitors C1, C3, fixed resistors R2, R4 (see diagram). Sound effects you can Supplement the indicator light, replacing the resistor R3 with a bulb from a pocket lantern 2,5ВХ0,1A. Output transformer and speaker from any small-sized transistor radio.
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