Stepper Motor Driver (74194)

Power Miser Version

  This circuit is based on the UNIPOLAR stepper motor shown on this site.

  The main feature of this circuit is low power consumption in the motor circuit. This is achieved by only turning on the individual outputs of the driver for 1/10th of a second for each step the motor makes.

  The motor only uses power when it makes a step. This would be ideal for a battery powered system.

  The main disadvantage of this circuit is that the maximum stepping rate is less than 8 steps per second. A secondary disadvantage is that the motor does not have any holding power because no coils are energized in the stopped state.

Input / Output Diagram

Schematic Diagram

  The inspiration for this circuit came from a email sent to me by someone who was using as similar circuit for a star tracking telescope system. The original circuit used 555 timers instead of the 74HC123 ICs shown here.

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Please Read Before Using These Circuit Ideas

  The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.

  If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.

  Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.

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11 February, 2009