Hall Effect and Motor Driver Interference

Feb 26, 2009
Category:Electronics Arduino 

My motor driver IC (L293D) arrived the other day, and before I put it to real use I thought I would just have a quick go at driving two motors at once...

I still had my hall effect controlled CD-ROM draw set up so I thought I would replace the four transistor h-bridge with the new chip, and be able to drive another motor at the same time. This second motor also came from a CD-ROM drive where I also found a two-way switch used to detect whether the draw was open or closed, I glued a bit of plastic to one of the cogs and attached the switch so that it would be activated by the piece of plastic allowing me to detect which way the motor was turning. I intended to change the direction of the motor when this happened to make it go back and forth.

The driving of the motors worked perfectly, however the fluctuating supply voltage caused by the starting and stopping of the motors interfered with the hall effect sensor.

I am fairly interested in solving this problem, but there are other things I want to be doing at the moment and I have dismantled the project. I did briefly try connecting the supply voltage directly to an analogue input, so I could detect a drop in the voltage and use this to compensate for the change in the hall effect input voltage, but this did not work. I also tried using  various capacities to smooth the supply, but again no luck as I think the fluctuations last for too long.

I am sure there will be a time when I run into this situation again but until then I am not going to worry, but feel free to propose a solution or make any suggestions and I may well give it a go.