Effects of a Motor on sensitive electronic components

[Xarren]

Hey, my first post on here, just wanted to ask how to calculate the effect of a motor, and a switching current in the wires supplying the power on the surrounding electronics.

The two motors will be supplied a PWM signal of 20Khz frequency, 5amp, 7v2 at 80% duty cycle. This is part of a project, where I will have a GPS unit which requires a maximum of 50microvolt fluctuations in its power supply - any more and it will not get a lock, and a magnetometre which is used for a heading and reference system.

How would I calculate the effects of those motors on those components? Also how would I calculate the effect of the cables supplying the motors on those components? I need to work out the minimum distance I need to place them from the motors, and should that not be achievable due to project size restrictions, I guess I may need to shield them.

Thanks,
X

EDIT: Just realized there is an electronic engineering section of the forum, if an admin happens to read this, could you please move my thread? << Done. >>

 

[schip666!]

I don't know about no calculating, but in general you need to be very careful with your power wiring and grounding. Run separate lines from the main power source to the motors. Ground everything at one point at the main power and avoid "ground loops" where a ground wire connects to that point from more than one direction. Use shunt diodes on the motor windings to minimize inductive kick-back. Bypass, bypass, bypass, capacitors in both large and small values -- small, like .1uf ceramic, for high frequencies. If possible put a voltage regulator at the GPS unit and run the motors off the raw supply. Shield interconnect cables, especially inputs, and especially remember the ground loop thing here.

Proper prophylaxis saves circuits...