safety guard


Posted on Feb 7, 2014

Protect your home appliances from voltage spikes with this simple time delay circuit. Whenever power to the appliances is switched on or resumes after mains failure, the oscillator starts oscillating and D5 blinks. This continues for three minutes. After that, Q14 output of IC CD4060 goes high to trigger the gate of the SCR through D4. At this moment, the voltage is available at the cathode of the SCR, which energizes the relay coil to activate the appliance and D6 glows. Switch SW1 is used for quick start without waiting for delay..


safety guard
Click here to download the full size of the above Circuit.




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