This timer circuit can be used for a particular device off after about 35 minutes. The circuit can be used to turn off devices like radio, TV, fan, pump etc., after a set time of 35 minutes. A circuit can certainly save a lot of energy.
The circuit is based on quad 2-input CMOS IC 4011 (U1). The resistor R1 and capacitor C1 produces the required delay too long. When the switch S2 button is pressed, the capacitor C1 discharges and the entry of the four NAND gates are pulled to zero. The four outputs short of U1 to go high and turn on the transistor Q1 to drive over. The device is connected through the relay is on. When S2 is released and C1 begins charging when the voltage at the positive pin is equal to half the supply voltage U1 outputs becomes zero and the transistor is off. This makes the relay off and the device connected through the relay off. The timer can be done to stop when necessary by pressing the switch S1.
The circuit is based on quad 2-input CMOS IC 4011 (U1). The resistor R1 and capacitor C1 produces the required delay too long. When the switch S2 button is pressed, the capacitor C1 discharges and the entry of the four NAND gates are pulled to zero. The four outputs short of U1 to go high and turn on the transistor Q1 to drive over. The device is connected through the relay is on. When S2 is released and C1 begins charging when the voltage at the positive pin is equal to half the supply voltage U1 outputs becomes zero and the transistor is off. This makes the relay off and the device connected through the relay off. The timer can be done to stop when necessary by pressing the switch S1.
