Simple manual control of stepper motors without a PIC or PC

stepper motors

This instructable will show you how to control stepper motors (Unipolar OR Bipolar) manually with a knob, without the use of a PIC or PC, so no programming is needed.  The position of the knob determines the position of the motor shaft, which will stay in that position until the knob is turned again.  The unipolar and bipolar circuits are different, but each requires only 1 chip.

stepper motors

Step 1: Here’s what you’ll need.

For the Unipolar board –     (1) rotary encoder

(4) 1K 1/4W resistors

(1) ULN2003 I.C.

For the Bipolar board –        (1) rotary encoder

(2) 1K 1/4W resistors

(2) 10k 1/4w resistors

(2) 2N3904 transistors

(1) L293D I.C. (or equivalent such as SN754410NE)

Step 2: Use Eagle files (below) or program of your choice to make the PCB’s for each board.

Eagle files for Unipolar Board:



How It Works

The rotary encoder provides 2 square wave type outputs, each 90 degrees out of phase.Each board converts those to 2 pairs of complementary outputs, which provide the proper sequence for full-step, high torque driving of unipolar or bipolar motors.(I used the EVQ-WTEF2515B from Electronic Goldmine), but you could use any quadrature type rotary encoder, including those found in computer mice (the scroll wheel).The sequence is reversed when the rotary encoder is turned the opposite direction.

Leave a Comment

Your email address will not be published. Required fields are marked *