circuit 9 second countdown power on

Posted on Feb 6, 2014

When the switch is opened, the timer produces an approximate 1 second clock signal, decrementing the counter until the 0 count is reached. When the zero count is reached, the `carry out` signal at pin 7 of the counter moves low, energizing the 12 volt relay and stopping the clock with a low signal on the reset line (pin 4). The relay will remain e

circuit 9 second countdown power on
Click here to download the full size of the above Circuit.

nergized until the switch is again closed, resetting the counter to 9. The 1 second clock signal from the 555 timer can be adjusted slightly longer or shorter by increasing or decreasing the resistor value at pin 3 of the timer.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    FM Electrocardiogram Monitor with LM331/LM231
    1.57-GHz Front-End for GPS Receiver
    Uhf Tv-Line Amplifier
    Preamp Transmit-Receive Sequencer Circuit
    Auto gain Control op-ampCircuit
    Driving a buzzer
    heater with ckm005 microcontroller
    HR Diemen
    Non-Contact AC Mains Voltage Detector
    Restructuring of the pitch by the pitch selector circuit