Applause bulb operated, how it's done

Discussion in 'The Projects Forum' started by Andres Mauricio, Oct 16, 2015.

  1. Andres Mauricio

    Thread Starter New Member

    Oct 16, 2015
    Theory of Operation

    When we welcome the MIC 1 picks up sound and converts it into electric current generating a signal of similar design this is entered into the integrated LM324 circuit which is responsible for amplifying, then the signal goes to pin 2 to integrated circuit LM555 this, configured as timer ie when the signal enters a set of square wave is generated at its output, pin 3 is digital square wave which is very convenient for us to configure the following integrated circuit Flip Flop 4027B CD as the analog signal generated by the Microphone is not compatible with the Flip Flop since this is digital.As we see in the background the digital pulse input for the clock pin of the integrated CD 4027 circuit this chip is configured as a divider 2 that is when you enter a positive pulse (1) is generated at the output Q1 a positive pulse (1) then when you enter another positive pulse is generated at the output Q1 a negative pulse (0) then we have a divide by 2 entered 2 positive pulses and only comes one of this form this chip acts as an ON / OFF switch (on and off) This signal reaches the transistor (NPN) 2N 3904 which amplifies the pulse generated by the flip flop at its output Q1 and in turn actuates the relay 12 V acting as high-current switch is actuated when the relay contact change position normally open to closed and vice versa turning on and off our 100-watt bulb every time we applaud, the rectifier diode 1N 4004 I is polarized in contrast to prevent high voltage pulses generated by the relay coil burn the transistor or other circuit component .

    circuit diagram:


    Video of the circuit in operation:

    Datasheet of integrated circuits that use

    Datasheet CD 4027

    Datasheet LM 324

    Datasheet LM 555

    Printed circuit tested


    link to download the printed circuit better resolution:

    The exact measurements of the printed circuit are 11.9 cm x 5.3 cm

    List of materials

    1 Integrated Circuit LM324
    1 Integrated Circuit LM555
    4027d cd 1 Integrated Circuit
    2 resistors 1k
    2 resistors 47k
    1 Resistors 10k
    1 Microphone
    1 relay 12V
    One led diode
    1 Transistor 2N 3904
    1 Bakelite for print 11.9 x 5.3 cm
    1 Lamp 100 W to 120 volts
    1 Battery
    1 connector battery
    cables and other

    Image printed and assembled


    This circuit design when I was in school I hope you like

  2. n1ist

    Senior Member

    Mar 8, 2009
    Careful - it looks like the AC inlet is wired across the relay contacts. That will go bang the first time the relay closes.

    Also, be careful about spacing when doing high-voltage circuits. It's hard to tell, but it looks like the spacing is a bit close between the coil trace and the trace to the center switched terminal on the relay, and between the black terminal on the AC inlet and the bare jumper below it.
  3. GS3

    Senior Member

    Sep 21, 2007
    Look again. There is a light bulb.
    I agree. I never liked this relay pin layout which, OTOH is pretty common. I make a point of clearly separating any part of the PCB which carries dangerous voltage and I cover it with tape if I need to work on the assembly.