9 Second LED Timer and Relay Circuit


Posted on Feb 7, 2014

This circuit provides a visual 9 second delay using 10 LEDs before closing a 12 volt relay. When the reset switch is closed, the 4017 decade counter will be reset to the 0 count which illuminates the LED driven from pin 3. The 555 timer output at pin 3 will be high and the voltage at pins 6 and 2 of the timer will be a little less than the lower t


9 Second LED Timer and Relay Circuit
Click here to download the full size of the above Circuit.

rigger point, or about 3 volts. When the switch is opened, the transistor in parallel with the timing capacitor (22uF) is shut off allowing the capacitor to begin charging and the 555 timer circuit to produce an approximate 1 second clock signal to the decade counter. The counter advances on each positive going change at pin 14 and is enabled with pin 13 terminated low. When the 9th count is reached, pin 11 and 13 will be high, stopping the counter and energizing the relay. Longer delay times can be obtained with a larger capacitor or larger resistor at pins 2 and 6 of the 555 timer.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Robot Train Cruise Control
    user-customizable PTT/FSK API of MMTTY
    Schematics High Power LED mood Lamp PCB
    1000 watt power inverter circuit diagram
    Tube preamp tone control
    DIY video dolly stepper motor driver
    always on for pcs circuit
    OSA Link Cable Schach computer
    455 kHz IF WITH AF COMPRESSOR
    Amateur Radio Projects
    8-bit bus control widely used 12-bit DA converter Universal
    DC relay circuit to accelerate the release



    Top