I have read several times in this forum about the use of ferrite chokes on long servo leads.

Would someone mind explaning just how and why these work the way they do ? Are they as good as or better in some applications as amplifiers ? What is the difference ? Just curious.....Thanks

Rod

Ferrite is a "ceramic like" material often used as the core material in the manufacture of inductors. Ferrite has a permeability much greater than air, so magnetic flux flows through the ferrite easily. Ferrites are low loss materials so they are useful at very high frequencies, unlike iron.

Ferrites are often used as common mode chokes where they can stop RF from leaking from a device, or to stop a device from being sensitive to external RF fields.

You can learn more about ferrite from one of the manufacturers, you look at the FAQs at www.fair-rite.com as an example.

In the case of RC servos I would suspect that long servo lines might radiate RF because of the very large current pulses taken by the servos under load. These pulses might radiate enough RF to interfer with the receiver, causing glitches. Putting one or more common mode ferrite chokes in the leads would help to "cut off" the high frequency antenna that the lead creates, and thus cut down on the radiated RF.

To add a ferrite choke to your system, you would just thread the servo leads (all three) through a ferrite toroid (shaped like a little donut) and secure the core to the wire with a bit of shrink tubing. You might also find split cores so you could put them around the wire more eaisly.

Will they help? Sometimes these chokes can make a world of difference. sometimes they do nothing. You'll have to experiment with your situation to find out. Nothing a few thousand dollars at a commercial testing lab couldn't unravel!

Amplifiers? The three servo leads are power, ground, and a control line. The biggest problem is weak power at the servo end of the line which can be helped by using larger wire, better connectors, storage capacitors, stronger batteries, or a separate power distribution network that will take the burden off the servo cables. If an "amplifier" helps out in any of these areas it probably is a good thing.

Sorry for the long story, but there is no simple answer to this question.

Rod,
There is another alternative:
http://www.rcuniverse.com/showthread...084#post541355]