Servos create interferance? Use capacitors?

bulkhead

I have a few metal geared servos that seem to intefere with my radio control system. Can I eliminate this by putting capacitors on the servos? Does it go between the power and ground wires? What size capacitor should I use?

Steve Joblin

Great question! I have had trouble getting reliable readings on my PING! sensor and I think it is due to the noise of the modified servo motors that I am using to drive my robot.

I have seen many motors in toys with a regular old ceramic disc capacitor across the (+) and (-) poles right on the motor... They usually seem to be 0.1uF if I remember correctly.

Are ceramic discs the best type to use for this? Are Tantalum better (but just not used in toys because of the additional expense?)

Beau Schwabe

I usually put a capacitor on the power supply right at the connector if there is going to be some distance between the actual servo and the controller. In one particular application,
this distance is about 20ft over a 5-conductor telephone cable. In this case the capacitor that I used was·1000uF. Also, at the far end (opposite of the servo) I use at least a 4.7K
resistor on the signal line (1mS to 2mS) from the controller output.

Reference:
Laser Pointer Organizer - project
Laser Pointer Organizer - schematic

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Paul Baker

also physically locating the servo as far away as feasible from the antenna and receiver helps since the motor in the servo creates free-air rotating electromagnetic waves.

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·1+1=10