Periodic Timer Timing


Posted on Feb 7, 2014

This timer circuit is similar to the 5 to 30 minute timer except that when switch S1 is closed, the on/off action of the circuit will continue indefinitely until S1 is opened again. A 7555 time and low leakage type capacitor for C1 must be used. The 6 way rotary switch S3 adds extra resistance in series to the timing chain with each rotation, mini


Periodic Timer Timing
Click here to download the full size of the above Circuit.

mum resistance point "a" maximum point "f". The 7555 is wired as an equal mark/space ratio oscillator, the timing resistor chain R1 to R6, being connected back to the output of the timer at pin 3. The output pulse duration is defined as:- This gives on and off times of about 379 seconds for position "a" of S3 (just over 6 minutes), to about 38 minutes at point "f". The times may of course be varied by altering R1 to R6 or C1.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Duty-Cycle Measurer
    Beat-Frequency Audio Generator
    Tone Burst Generator Circuit
    200mA/Hour 12V NiCAD Battery Charger
    electronic door buzzer circuit schematic
    LM331 Frequency to Voltage Converter
    USB 8bit Interface Board
    Optical tracking control circuit
    RFID security access project using Arduino Uno



    Top