Ambulance (Hee-Haw) Siren

The circuit below consists of two multivibrators. The first multivibrator provides the speed of the change from “hee” to “haw” and operates at a low frequency. By allowing full voltage to appear at the bottom of the 220R and then a slightly lower voltage when LED is illuminated will modified the voltage to the tone multivibrator.

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Fastest Quiz Bell/Alarm

This is aquiz bell/alarm circuit. This circuit indicate “fastest finger first”. This circuit has one bulb for Quiz master and one for each contestant. The bulb will illuminate when a button is pressed. the cathode of the 9v1 zener sees approx mid-rail voltage. The Quiz Master bulb is also illuminated.  Here is the circuit: There is no other bulbs can […]

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Dual Tone Single IC Siren

This circuit is a double tone Police sound and Single tone old ambulance sound. This circuit is usually installed on a on battery powered cars, motorcycles, and bicycles for fun kid not only that, this circuit also used in  models and other games. The oscillation of IC1A and IC1B gates produces the typical dual tone sound of Fire-brigade  or Police […]

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