Making an ESC...

[BrianG]

I've been reading up A LOT on how servos work for an electronic project I've been working on and realized a simple brushed ESC can be created with just a few dollars and an old servo that has broken gears or motor.

Generally speaking, the circuitry in a servo is simply a speed controller with feedback. The tiny servo motor moves according to the transmitter until the feedback potentiometer tells the circuitry that the motor is in the right position and stops powering the motor. If you remove the feedback, the output of the servo circuit (the motor) stays on until the transmitter is back to neutral - thus becoming a simple speed controller. The output is of the circuit is a varying PWM signal just like the big boys so the speed is variable.

The purchase of a couple inexpensive of MOSFETs and a little soldering on a PCB should work quite nicely. Just replace the feedback pot with a slightly different resistor/pot setup to fine-tune the "off" position. MOSFETs can be purchased for a dollar or two that can handle a LOT of current and voltage. Plus, being MOSFETs, they have high input impedance, therefore easy to use.

Specifically, the servo circuitry I've used is based on the M5166OL IC chip, which is commonly used in servos to translate the 1-2ms pulses from the receiver into something usable.

Anyway, if anyone is more interested on the subject, I can elaborate on the theory and electronics involved...