Here's how you can make an electronic speed controler (ESC) for your remote control car, boat or even an airplane using an old servo and some MOSFETS
Please note that this ESC has a very limited control range. Meanining that it will act almost like but better then a switch.
What you need:
Servo Mosfets (see below) 500 ohm Resistor(s)
Choose from the following mosfets: IRF530 or IRL2203N.
When using more than one mosfet, use the same type (either IRF530 or IRL2203).
SPECS. IRF530 IRL2203N Units Manufacturer Fairchild Semiconductors International Rectifier - Type N-Ch N-Ch - ECG Part # 66 n/a - Max Current @25°C 14* 116 A Max Current @100°C 10 82 A Max Voltage 100 30 V Data Sheets -
* Based on Mosfet by Fairchild Semiconductors. (Varies with manufacturer)
Note: IRL 2203N is a better mosfet for the use here and I highly recommend using it. However IRF 530 is easier to find.
It is strongly suggested that more than one mosfet are used.
Schematic diagram of the electronic speed controller.
MOSFETS are drawn this way for ease of construction.
Get an old servo where the servo amplifier still works. Cut off and remove the motor from the servo but leave some wire from one of the cables leading to the servo motor. Connect this cable to a 500 ohm resistor. Then connect that to the GATE (G in diagram) of the MOSFET. Find the negative wire of the servo which leads to the receiver, solder some wire onto it and connect that to the SOURCE (S) of the MOSFET and the negative port on the battery for the motor (note: this is not the battery for the receiver). Then connect the DRAIN (D) of the MOSFET to the negative port on the motor. Then connect the positive port of the motor to that of the battery. When using more than one MOSFET, use a seperate resistor for each one (see diagram below).
Schematic diagram showing the ESC with 2 MOSFETS connected in parallel.
Note that there is a seperate resistor for each MOSFET.
Continue to add MOSFETS and resistors as necessary.
Using three IRF530 Mosfets
Click on picture to enlarge
The thick blue lines in the diagram show where thicker cables should be used.
A couple of MOSFETS should be connected together. The more you use the smaller the energy loss. You should also put some heat sinks on the MOSFETS because they tend to heat up during use.
This electronic speed controller is for forward use only which means your model can't go backwards.
There are currently no plans for an ESC with REVERSE and/or BRAKE.
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Last updated 09-05-2002 Webmaster