powerful security siren


Posted on Feb 6, 2014

A complementary transistor pair (Q2 & Q3) is wired as a high efficiency oscillator, directly driving the loudspeaker. Q1 ensures a full charge of C2 when power is applied to the circuit. Pressing on P1, C2 gradually discharges through R8: the circuit starts oscillating at a low frequency that increases slowly until a high steady tone is reached and kept indefinitely. When P1 is released, the output tone frequency decreases slowly as C2 is charged to the battery positive voltage through R6 and the Base-Emitter junction of Q2. When C2 is fully charged the circuit stops oscillating, reaching a stand-by status..


powerful security siren
Click here to download the full size of the above Circuit.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    fahrenheit thermometer circuit
    2G—22W Stereo Car Audio Amplifier schematic diagram
    High Voltage Generation For Xenon Tube Applications
    High Side Current Monitor
    499 Robot
    digitally controlled oscillator dco design
    Optical Theremin
    Serial LCD Library
    Schumann Resonance Converter
    BA5173 produced by multi-function lamp dimmer
    LM629PWM drive



    Top