Bi-directional motor

john June 2, 2009 1 Comment
Description. This is a simple and easy to construct circuit that can be used to provide a bidirectional drive to a DC motor. The circuit operation is straight forward. Output of an astable mutivibrator based on IC1 (NE555) is used to control the relay RL1 driving the motor. The motor is connected between the two poles of the relay contacts. The relay contacts are so wired as to reverse the DC supply to the motor when the contacts changeover....
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Temperature controlled DC fan

admin August 30, 2008 10 Comments
Description. Here is a simple circuit based on two transistors that can be used to control the speed of a 12 V DC fan depending on the temperature.A thermistor (R1) is used to sense the temperature. When the temperature increases the base current of Q1 (BC 547) increases which in turn decreases the collector voltage of the same transistor. Since the collector of Q1 is coupled to the base of Q2 (BD 140), the decrease in collector voltage of...
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Stepper motor controller

admin March 7, 2012 15 Comments
Description. Here is the circuit diagram of a simple stepper motor controller using only elementary parts. The driver circuit uses, four transistor (SL100) to drive the motor windings, two NOT gates and one XOR gate to decode the two bit control logic to drive the four windings of the motor. The diodes D1 to D4 protects the corresponding transistors from transients generated during the switching of motor windings. d0 and d1 are the control logics which determines the direction...
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PWM Motor Speed Control Circuit

admin November 15, 2011 9 Comments
PWM Motor Speed Control Description Here is a simple PWM motor speed controller circuit that can be used for varying the speed of low power DC motors . The variation in speed is achieved by varying the duty cycle of the pulse supplied to drive the motor. Of the two gates of IC CD40106B , N1 is wired as an inverting Schmitt Trigger astable multi vibrator for producing pulses and N2 as an inverting buffer to drive the transistor...
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