Stopping Oscillations in an R/C Hobby Servo

First, are you using a "servo" or an "electric motor"? Electric motors require the proper driver. There are several "voltage regulators"/ "speed controllers" available for the size of motor you are using. Each motor has there own power ratings and specific voltage regulator required for the proper opperation of the motor. If you are using a regulator for a larger motor, then you will "over current" and heat up your motor. Most of these electric motors are designed to be used in an air craft that is moving up in the "air". Note if you are using this motor at a stationary position, you need to incorporate a cooling system for your motor. They will heat up when in usage. These are developed for "airplanes" that have a built in cooling system! If your "voltage regulator" is not rated for your particular motor, it will over current your motor and burn it up quite rapidly. These parts can be found through a hobbie store or even better, on the net under "R/C electric motors" in your search engine. Second, if you are using a "servo", which is a low voltage, low current, device for driving control serfaces on an "aircraft", you can not use the "micro-electric motor" from this device on anything that requires a great amount of torque. These motors are designed to only have a small amount of voltage applied to their coils to work, plus they are designed to work by-directional. Micro-volts and milli-amps! These are geared at a ratio of ~ 100:1 output ratios of torque. You cannot use the servo motor for anything that will cause these "micro-motors" to over current. Your best choice is to use an electric motor with the proper voltage regulator and there are gear reduction drives that will help in your application. You can obtain a drive kit in which you build and have the ability to change the ratio for a particular output speed. As far as your non-linear and jittery problems, this is due to the mis-matched speed controller/ voltage regulator being used with your application. Good luck with this build.

For the record; are you actually using an "electric R/C motor" used for flying an aircraft? You mentioned a gear reduction system. You need to be more specific of your proplem using the proper terminology for your problem. Your R/C servo unit, when used in its' properly designed orrientation, will have the jitters if there is interference from another transmitter in the area. The receiver will pick up "ALL" radio waves that are with in its' frequency band width. We use a frequency scanner at our flying field to find which frequency is being disrupted. This helps in the case of loosing control of any specific radio being used. As far as your mentioned problem, is this being used in an aircraft or another factioned other then R/C flying? Your servo could have a loose connection if you have changed out an existing micro-motor to another housing. If there are loose connections on the drive motor, then you will have possible short. Otherwise if this is an aircraft application, you have several situations that can cause the jitters. Is your receiver crystal the correct bit? Has it been changed out from another radio pack? If so, you should consider having it calibrated and tuned to your transmitter. If you are using an electric motor, with a gear redux system to fly an airplane, has your prop been balanced? Are you trying to used too large of a redux rate for your electric motor? Certain motors can only handle "X" amount of current load. If there are "NOISE" problems comming from your motor, then you need to incorporate some small capacitors accross your hookups to help quell the frequency disturbance. Plus, you should have your receiver insullated and away from your main electric motor. There shuld be at least two firewalls and a minimum of 4" distance away from your drive motor. Your receiver should be located behind the voltage regulator/ speed controller of your electric motor. Your build should be, motor on the forward bulk-head, speed controller behind the first bulk-head compartment, a bulk-head between the controller and the receiver and servo tray compartment. This will help quell your interference on the receiver. Next make sure your prop has been balanced! This is the best you can do and make sure your motor is rated for the particular gear redux system being used. Too much of a load on the electric motor will overheat and distroy your investment. I fly with the Hill AFB Falcons R/C group in Utah, USA. There are several electrics out here and it is common for someone to burn up an electric due to not allowing it a cooling down period. These motors can only go for about 15 minutes of full out flying before they start to come apart from the heat. If you are using a an un-balanced prop, this will increase the load problem and cause your vibration jitters. Plus a miss-alignment of the gear redux to your motor can cause a sevear vibration at full load. You need to create a test bed for your motor, gear redux and prop assembly, then put it through a pre-install testing. This can help you find the culprit and then you will know where to start on the fix. Sorry about the first comments stated, I had to re-read your problem and deciffer the quest you are on. You mentioned problems that led me to beleive you had pulled apart a servo micro-motor and was trying to use it out of its' own environment. There are several places on the web that are specific for electric flight, I am sure you can get an electrical schematic on how to improve your noise problem as well. Good luck.

Generic response: Tap the R/C motor and provide a adjustible Biased negative feedback to the input of the servo amp. Adjust bias until the R/C motor comes into control. Good luck, Fris.

Most R/C servo amps that I've fooled with put out PWM pulses at a fairly low frequency. The guts of the R/C transmitter would have to be changed to "fix" that problem, and it wouldn't be simple. Your "coreless" motor may have a mechanical time constant which is on the same order as the pulse frequency, causing it to oscillate in response to the on-off nature of the amp output. If the voltage of the power supply is greater than the rated voltage of the motor, it will overheat. Make sure that the voltage is low enough. Of course, adding inertial mass to the motor to increase the mechanical time constant defeats the purpose of using a low-inertia motor.