C4164 Light Sensitive Sound Generator

Discussion in 'The Projects Forum' started by prismatic1, Aug 7, 2011.

  1. prismatic1

    Thread Starter New Member

    Aug 7, 2011
    Hey all. I am just beginning with electronics and I bought a kit to make this sound generator. I soldered everything together and it works which is great, but I don't understand how it works which is frustrating and lame. I know what all the symbols stand for on the schematic, but I don't know how they are working together to make the thing work and I don't understand how the power is flowing through the circuit..... any help would be very much appreciated.

    The parts included are:

    1x .022 microfarad Disc Capacitor
    1x 4001 CMOS IC
    1x MPSA 13 Darlington Transistor
    1x 24K ohm Resistor
    1x 150 ohm Resistor
    1x 510 ohm Resistor
    1x Speaker
    1x CDS Cell
    and then a 9v batter connector, wires for the speaker, and a 14-pin IC socket.

    I think probably you guys with experience already know how it would be assembled, but if you want the schematic I can probably scan it or something....

    I really want to understand circuits and maybe someday make a circuit of my own without instructions...please help me out eh.

  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010

    I think this is similar schematic to your circuit. I'm pretty sure that U1A and the CDS cell are setting a DC voltage level for the Cap(C1). The other two gates are arranged as an oscillator. The output of each one feeds back into the input of the other. The DC voltage level on C1 sets a threshold at which the oscillator will toggle its output. Meaning it determines the frequency of the two gates oscillations. The change of resistance created by CDS varies the voltage and therefor makes the oscillations change with varying light levels.

    Your kit uses different parts but should be arranged in very similar manner. The transistor is probably acting as an amplifier for the speaker. Your kit has a different value cap and some different value resistors, but react the same as the one above.