Low Voltage High Current Time Delay Circuit


Posted on Feb 6, 2014

In this circuit a LM339 quad voltage comparator is used to generate a time delay and control a high current output at low voltage. Approximatey 5 amps of current can be obtained using a couple fresh alkaline D batteries. Three of the comparators are wired in parallel to drive a medium power PNP transistor (2N2905 or similar) which in turn drives a


Low Voltage High Current Time Delay Circuit
Click here to download the full size of the above Circuit.

high current NPN transistor (TIP35 or similar). The 4th comparator is used to generate a time delay after the normally closed switch is opened. Two resistors (36K and 62K) are used as a voltage divider which applies about two-thirds of the battery voltage to the (+) comparator input, or about 2 volts. The delay time after the switch is opened will be around one time constant using a 50uF capacitor and 100K variable resistor, or about (50u * 100K) = 5 seconds. The time can be reduced by adjusting the resistor to a lower value or using a smaller capacitor. Longer times can be obtained with a larger resistor or capacitor. To operate the circuit on higher voltages, the 10 ohm resistor should be increased proportionally, (4. 5 volts = 15 ohms).




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    2x300W or 600W Power audio Amplifier
    Simple color organ
    FT232RL USB to Serial Adapter for PIC AVR ATMEGA ARDUINO MCUs
    The Autonomous Drifter Circuit
    CPD type forklift battery control circuit



    Top