Introduction: DC Motor Multiplexer

Picture of DC Motor Multiplexer

This DC Motor Multiplexer allows you to control up to four DC motors in forward and reverse using one MOSFET and only 5 digital pins.

For this intractable you will require:

- DC motors (I used salvaged DC fans)
- MOSFET (I used a 110v 30amp make sure it is rated for more than your combined fans)

- Solder less bread board

- Jumper Wires

- LinkIt One (or another micro-controller)

- 9volt battery and connector

- 8 relays

A huge thank you to instructables, autodesk, MediaTek, and Penolopy Bulnick for sending me the Link It One used in this instructable.

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Step 1: Controller

Picture of Controller

First place the MOSFET onto the bread board, then connect the battery connector to the power rails. Place a jumper wire from the hot power rail to one side of the MOSFET gate, and a second jumper wire on the other gate to connect the motor. Place a data wire from the control pin to one of the PWM digital pins (i.e. Pin 9).

Step 2: Relays

Picture of Relays

From each relay control pin split the jumper wire into two jumper wires and use them to control each pair of side by side relays. The first relay of each pair will be positive, and the second relay will be neutral. Then the left contact of the relay pair will be for one direction and the right for the opposite direction of control.

NOTE: This multiplexer can control all four motors simultaneously, but can only have a single power setting, but the direction can be reversed.

This setup would work perfectly for a Skid Steer robot design or for a system which only requires the movement of one motor or a pair of motors at a time.

Step 3: Coding

To control the speed of the motor set pin 9 to be an output and send a value between 0-255 to the MOSFET.

0 is no movement and 225 is full speed.

The digital pins used to control the pairs of relays must be set as outputs. When nothing is being set to a pair of relays they will turn the motor in the native direction of the relay (marked by the solid line), and will reverse the motor when a HIGH signal is sent.

If you have any suggestions for improvement, questions, or photos of you own projects make sure to comment below.
Have a great day! :-)

Comments

DIY Hacks and How Tos (author)2015-12-21

Nice design. I usually just use an H-Bridge of power transistors. But your design would work better for higher power motors.

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