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AMBULANCE SIREN
Materials required - Carbon resistors [.25W] 150 ohm(2), 470 ohm(1)
- Electrolytic Capacitor 100 mF,16 V
Construction:Here is a design for your familiar ambulance siren
A six volt DC supply is required for the proper functioning of this project. Hence we use 4 torch cells in series to obtain the required voltage.
Circuit Diagram:
Click on the picture to enlarge
The capacitor is used to regulate the output from the DC batteries. When the switch (S1) is closed the IC (UM 3561) receives the required supply through resistor R1 and zener diode. Immediately the IC functions and we receive the sound of the siren through the speakers. The transistor (SL 100B) functions as an amplifier to amplify the output through the speakers.
The LED functions only when the circuit is completed and is protected from excess current by the resistor R1.
