Rangkaian Unipolar Stepper Motor Driver

Stepper Motor Driver PCB Circuit

The following schematic is for the printed circuitboard version of the 2008 stepper motor driver.

Rangkaian Unipolar Stepper Motor Driver

Basic Controls For The Stepper Driver

The direction is selected by an ON-OFF-ON toggle switch.

The stepping rate is shown being set by a 1 Megohm potentiometer (RT). Using the component values shown for R1, RT, R2 and C1, the calculated step rate range is between 0.72 steps per second (1.39 seconds) to 145 steps per second.

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Basic Stepper Motor Driver Operation

1. The LM555 (IC 1) astable oscillator produces CLOCK pulses that are fed to PIN 11 of the 74194 (IC 2) shift register.

2. Each time the output of the LM555 timer goes HIGH (positive) the HIGH state at the 74194's OUTPUT terminals, (PIN's 12, 13, 14, 15), is shifted either UP or DOWN by one place.

   The direction of the output shifting is controlled by switch S1. When S1 is in the OFF position (centre) the HIGH output state will remain at its last position and the motor will be stopped.

   Switch S1 controls the direction indirectly through transistors Q2 and Q3.

   When the base of Q2 is LOW the output shifting of IC 2 will be pins 15 - 14 - 13 - 12 - 15; .etc.

   When the base of Q3 is LOW the output shifting of IC 2 will be pins 12 - 13 - 14 - 15 - 12; .etc.

   The direction of the output's shifting determines the direction of the motor's rotation.

3. The outputs of the 74194 are fed to four sets of paralleled segments of a ULN2803 Darlington driver (IC 3).

   When an input of a ULN2803 segment is HIGH, its darlington transistor will turn ON and that OUTPUT will conduct current through one of the motors coils.

4. As the coils of the motor are turned ON in sequence the motor's armature rotates to follow these changes. Refer to following diagram.

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IC SN74194 Stepper Motor Circuit

This circuit is a circuit diagram of the driver to adjust the motor speed at STEPPER motor. This motor circuit can drive a motor 12v to 24V. Test series are placed differently and show SN7474 in logic block form and LED lights are used to indicate the motor coil is removed. STEPPER motor circuit uses IC 555 astable oscillator produces a series of clock pulses fed to Pin 11 of integrated circuit SN74194. Every time the clock pulse goes HIGH (positive) in the country in the SN74194’s HIGH OUTPUT terminal (PIN’s 12, 13, 14, 15), transferred either UP or DOWN y one place. Referring to the “Stepper Motor Driver Waveforms” diagram. Shift direction is controlled by a switch S2. The following is a schematic drawing:

IC SN74194 Stepper Motor Circuit

When S2 is in the middle position OFF HIGH-state output will remain in last position and the motor will be stopped. When the base of Q6 is a shift to PIN LOWER 12-15 – 14 – 13-12. When the base Q7 is a shift to PIN LOW 12 – 13 – 14 – 15 – 12. Direction of the shift pulses determine the direction of motor rotation. The pulses from the OUTPUT’s of SN74194 four segments are fed Driver ULN2003. When the input of a segment is HIGH, it will activate the Darlington transistor and OUTPUT will conduct current through one of the motor coils. As the roll motor turned ON in order to follow the motor rotates these steps.

Source: home.cogeco.ca

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Simple Motor Stepper Controller Circuit

The circuit shown above can be used to control a unipolar stepper motor which has FOUR coils (I've swiped it off an old fax machine). The above circuit can be for a motor current of up to about 500mA per winding with suitable heat sinks for the SL100. For higher currents power transistors like 2N3055 can be used as darlington pair along with SL100. The diodes are used to protect the transistor from transients.

Activating sequence:-

Inputs		Coils Energised
D0	D1
0	0	A,B
0	1	B,C
1	0	C,D
1	1	D,A

To reverse the motor just reverse the above sequence viz. 11,10,01,00.

Alternately a 2bit UP/DOWN counter can also be used to control the direction , and a 555 multi-vibrator can be used to control the speed.

Via: http://www.electronic-circuits-diagrams.com/robotimages/robotckt1.shtml

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