Using Opto-Isolators to Prevent Interference

Noise Interference From Motors

Often when trying to drive a DC motor with a PIC using transistors or H-Bridges, you will notice that the PIC is doing strange and unpredictable things. When this happens, the culprit is likely to be electrical noise being injected into your circuit by the brushes and spinning magnets in the motor. Unfortunately, this noise is very difficult to remove. One way of dealing with it is to try to filter out the noise by decoupling your motor driver circuit and logic circuit with ferrite beads, inductors, capacitors, and resistors. Unfortunate, the Mechatronics Lab stocks neither inductors nor ferrite beads, which limits your options for passive filtering.

A better method to isolate circuits is to use Photodiodes_and_Phototransistors#Applications.