DC Motor Causes Servo Problems

brian6592

I did a little searching today trying to pinpoint my issue with no clear results. I am using the BOE BOT with the basic stamp II chip. It comes with 2 servo motors, which have worked perfectly until now. I am trying to connect a fan that is powered by a standard dc motor, and while i was testing it (just hooked it up to the VDD and VSS terminals) the two servo motors started slowly turning, and as i applied torque to the fan blade, the wheels began to turn faster (both in the same direction, making the robot rotate in place). Any ideas on what to try next? Do i need resistors or other components to neutralize the issue?

Any help is greatly appreciated,

Beau Schwabe

A Diode-Capacitor filter to your DC motor Supply might be all you need... Make sure that your diode is rated high enough to handle the current of your motor. The Capacitor should have a voltage rating of at least twice the supply voltage.

       Diode
VDD >---->|----o-----> DC Motor
               |+
              --- 1000uF
              ---
               |
VSS >----------o-----> DC Motor 

See a similar problem here...
http://forums.parallax.com/showthread.php?130975-Constant-current-driver-interfering-with-audio-amp

erco

... and/or a 3-cap delta noise filter across your DC motor leads. Called a 3-cap filter here: http://www.beam-wiki.org/wiki/Reducing_Motor_Noise

Also make sure your fan motor isn't simply drawing too much current, causing your supply voltage to drop and reset the Stamp.