1) Servo information

All RC servos have a three wire connector. One wire supplies positive DC voltage – usually 5 to 6 volts (HV servos can handle up to 8.5 VDC). The second wire is for voltage ground, and the third wire is the signal wire. The receiver “talks” to the servo through this wire by means of a simple on/off pulsed signal.

Servos basically come in 4 different sizes (micro, mini, standard, and giant or 1/4 scale) to accommodate the type of RC models they are being used in. There are slight variations depending on the specific application but for ease of explanation, these 4 sizes cover most of the RC servos out there.

When selecting a servo for use with a model look at the size and specifications of the model, the type of radio gear in use i.e. is the receiver cable of supporting HV servos,  note that most standard receivers operate from 4.8 - 6 volts, HV or high voltage receivers operate from 2S, 2 cell Lipo’s (7.4 volts). DO NOT UNDER ANY CIRCUMSTANCES OPERATE A STANDARD RECEIVER FROM A 2 CELL LIPO WITHOUT A REGULATOR, DAMAGE TO THE RECEIVER MAY OCCUR. If the model is to be used for aerobatics, 3D or helicopters then the servo selected should have a reasonable fast reaction time and fitted with ball race bearings to prevent movement ‘slop’ and be of adequate torque to operate the control surfaces.

When selecting the servo arms for the servo make sure that the correct servo arms are obtained for that particular manufactured servo, i.e. Hitec servo arms will not fit Futaba servos, servo’s dependant on manufacturer have different ‘spline’ requirements, and the Hitec output shaft is slightly smaller therefore the JR / Spektrum arms will give a ‘loose fit’ when fitted to the Hitec servo, this may result in damage to the servo arm teeth / splines and a loss of a model, so only fit the correct servo arm recommended for that servo or suffer the consequences.

When using non Futaba servos with Futaba radio equipment you will notice that the centre point for the servo will not be accurate as Futaba radio gear uses a slightly different pulse width (1.52ms) (1 millisecond is 1000th second) to centre their own servos whereas Hitec, JR, Spektrum servos use a pulse with of (1.5ms), the error for the centre position on Futaba radio equipment may be corrected by the use of the ‘Sub Trim’ adjustment on the transmitter, the same effect will occur on Futaba servos used with other manufactures radio equipment.

Only use the servo arms recommended for that servo or you may loose your model.