My Circuit

Description    This circuit is intended for children fun, and can be installed on bicycles, battery powered cars and motorcycles, but also on models and various games and toys. With SW1 positioned as shown in the circuit diagram, the typical dual-tone sound of Police or Fire-brigade cars is generated, by the oscillation of IC1A and IC1B gates. With SW1 set to the other position, the old siren sound increasing in frequency and then slowly decreasing is reproduced, by pushing on P1 that starts oscillation in IC1C and IC1D. The loudspeaker, driven by Q1, should be of reasonable dimensions and well encased, in order to obtain a more realistic and louder output. Tone and period of the sound oscillations can be varied by changing the values of C1, C2, C5, C6 and/or associated resistors. No power switch is required: leave SW1 in the low position (old-type siren) and the circuit consumption will be negligible. Circuit Schematic Diagram Parts: R1 = 470K - 1/4W Resistors R2 = 680K - 1/4...

This is the simple ic based Siren Alarm Circuit Diagram. This siren alarm circuit may provide the final building block in an alarm circuit using a relay to activate it. This siren circuit is very simple and is constructed using common electronic components . Siren Alarm Circuit Diagram   When the switch is pressed C3 charges up through R4 with a time constant of 0.47 seconds and when the switch is released C3 begins a slower discharge through R7 and R3 with a time constant of about 5 seconds. The op amp 358 used in this project is set up as a voltage controlled oscillator. When the output of the oscillator (pin 7) switches low there is a charge remaining in C1 which holds pin 5 below the switching point. Current through R7 is proportional to the control voltage on C3. This current discharges C1 causing the voltage on pin 5 to rise towards the switching point at a rate proportional to the voltage on C3. When the switching point is reached pin 7 switches high and initially pul...

Devices such as Burglar alarms and sirens, whose basic purpose is to monitor certain conditions make enjoyable projects because of the variety of sounds they can generate. Here we are going to discuss a simple dual tone alarm/siren circuit using a dual op amp MC1458, audio amplifier LM380, and a 1-W speaker. The dual op amp is used as a signal generator that produces square, pulse and triangular or sawtooth waveforms. CIRCUIT SCHEMATIC FOR DUAL TONE SIREN Read More.....