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Standard Shield Using Darlington NPN Transistors (MEC155E)

This circuit was adapted from my book Robotics, Mechatronics and Artificial Intelligence (sold out) published in the United States. It can be used as a control shield for stepper motors in a mechatronics or robotics project or as a building block for simple projects. The block shown in MEC154E needs less power to drive high-current stepper motors from TTL, CMOS, or other drive circuits. The circuit requires less than 1 mA to drive motors, depending on the transistors.

For the recommended transistor, currents up to 1 A can be controlled. If you need more current, see Chapter 3 for directions on how to select a more powerful transistor.

A translator or microcontroller must be used to produce the sequence of pulses according the position or the speed needed in your applications. Remember that the power transistors must be mounted on heat sinks.


Figure 1  Driving a stepper motor with Darlington NPN transistors.
Figure 1 - Driving a stepper motor with Darlington NPN transistors.