Electronics Motor Controller

Here is a circuit used to control motor more efficiently than any electromechanically controlling device. The project shown here is cheap and easy to construct. It also overcome the problem of noise triggering and noise pulse.

Circuit description

The power supply is given by pressing switch SW1 it shots the N/O contact of relay RL­1 which gives supply to the circuit. The current through resistor R8 gives the base current to transistor T5. Where transistor T1, T2 and T3 from the over and under-voltage cut-offs. Here the transistor T4 on when over or under voltage is given to transistor T3.

For avoiding noise capacitor C2 with resistor R10 form a loss-pass filter and also give sufficient time delay. Here the resistor network (R11, R12, VR1) are used as current sensor. Where Diode D3 is as rectifier and capacitor C1 is used as noise filter of switching circuit.


Resistors (all ¼-watt, ± 5% Carbon)

R1 = 150 KΩ

R2 = 33 KΩ

R3 = 6.7 KΩ

R4 = 100 KΩ

R5 = 39 KΩ

R6 = 15 KΩ

R7 = 10 KΩ

R8 = 4.7 KΩ

R9 = 75 Ω/1W

R10, R13 = 47 KΩ

R11 = 470 Ω

R12 = 0.5 Ω

VR1 = 2.2 KΩ


C1 = 1000 µF/25V

C2, C3 = 47 µF/10V


T1, T2, T3, T4 = BC148

T5 = SL100

D1, D2, D3 = 1N4001

ZD1, ZD2 = 3.1V

ZD3 = 9.1V


SW1, SW2 = Push to on switch

X1 = 230 primary AC primary to 18-0-18, 500mA secondary transformer


(110 primary AC primary to 18-0-18, 500mA secondary transformer)

RL1 = 12V, 200 Ω Double pole double throw

M = Motor

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