Stepper motor gives a simple, low cost, and accurate position control. Stepper motor can be driven by circuit mounted close to the motor, and controlled by a remote control circuit through long cable.  The interesting thing of this circuit is that the power for both motor and the driver circuit is carried over two wires, the same wires that carry the control signal. Here is the schematic diagram of the circuit:

stepper motor controller circuit schematic

LMC555 CMOS timer integrated circuit  (IC1) generates 200 microsecond pulses to step the motor and control its speed. The speed of the motor can be changed by changing the frequency of this pulses, R1 variable resistor is provided for this purpose.  At the output of IC1 (pin 3), a negative going clock pulse drive the gate of IRL530N (Q1) power FET that momentarily turns OFF and disconnects the driver board from ground. This power interruption sends a signal to the motor driver to step the motor. The rotation direction is controlled by the polarity of the voltage applied to the driver circuit through interconnect lines L1 and L2.

MPSA05 Bipolar NPN transistor Q2 and MPSA55 PNP transistors Q3 and Q4 invert the pulse from pin 3, pull the drain of Q1 UP when it is OFF. Toggle switch S1 sets its direction by switching polarity. Pushbutton S2 starts and stops the motor by turning the clock on and off.

Parts

C1 – .47 MFD 35 volt tantalum
C2 – 1000 MFD 35 volt electrolytic
C3 – .1 MFD 50 volt metalized film
C4 – .001 MFD 50 volt metalized film
C5 – 100 MFD 16 volt electrolytic

R1 – 5MEG potentiometer
R2, R8, R10 – 100K 1/8 watt 5%
R3 – .56K 1/8 watt 5%
R4, R5, R7 – 10K 1/8 watt 5%
R6 – 2K 1/8 watt 5%
R9 – 4.7K 1/8 watt 5%

Q1 – MPSA05 NPN transistor
Q2, Q3 – MPSA55 PNP transistor
Q4, Q5, Q6, Q7, Q8 – IRL530N Hexfet

D1, D2, D3 – 1N914 silicon diode
D4, D5 – 1N4752 zener diode
D6 – 1N4004 rectifier

BR1 –  2 AMP 400 volt bridge rectifier
IC1 – LMC555 CMOS timer
IC2, IC5 – 78L05 5 volt regulator
IC3 – CD4013 dual D flip flop
IC4 – CD4070 quad exclusive or

S1 – momentary N/O push button switch
S2 – double pole double throw toggle switch

T1 – DC or AC adapter transformer to match motor
IC socket – 1 eight pin
IC sockets – 2 fourteen pin
Terminal blocks – 2 two position

M1, M2 – two phase unipolar 24 volts

For more information about this kit, please contact:

Glolab Corporation
134 Van Voorhis
Wappingers Falls, NY 12590
http://www.glolab.com
email  kits@glolab.com
fax  (914) 297-9772