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DIY Electronic Speed Controller

Part II: Tips and Photos - This is the conclusion of the tutorial for making your own electronic speed controller, for your RC airplane, boat, or car. Hopefully you've read Part I: Drawings and Procedure.

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Some Building and Use Tips:

-Current Capacity.  The power amps used in the photo above are each rated for 20 Amps.  What do you do if your RC airplane system is designed for 35 Amps?  You simply connect another resistor and amp in parallel to the first.  Parallel connection just splits the load, so that a set of twice as many resistors and amps can carry twice as much current. 

The diagram in Part I shows one resistor and one amplifier; if you need 40 Amps just add another resistor and amp:

schematic drawing of DIY electronic speed controller

                                            Copyright©2005 RC Airplane Advisor

-Wire stripper.  If you like electric rc models and don't have a wire cutter / stripper, get one.  You'll save a lot of time compared to using a knife to trim insulation from the wire. 

-Circuit Board.  These boards with the copper-coated holes are available from Radio Shack.  Very convenient for this project, though not essential.

-Zip Ties.  Great for securing the power wires.

-Cooling Air.  It's tempting to mount the ESC on the flat side of the power Amp, using velcro.  Don't!  Mount that side outwards, to allow better cooling.  This is especially true if you are doing an install with limited airflow, e.g. boat.  Try mounting with velcro on the old servo case. 

-Zero the Pot.  You may find that the motor system wants to run even with your radio transmitter stick at the zero throttle position.  If so, adjust the turning knob on the pot till it stops running.  Then drop a bit of CA glue on the knob to keep it fixed in position. 


Here are some photos of a completed controller.  This one uses three Power Amps and three resistors.  It is capable of handling 60 Amps and will be used in an RC boat. 

overview of diy speed controller


top of electronic speed controller showing power amps


bottom of electronic speed controller showing recycled servo and resistors