RC Cars and Trucks

How To Build a Cheap RC Car Dynamometer

RC Car Dyno - Cheap and Home Built

Photo: Tamiya F103 on top of the home made dyno (a rear pod of another F103).

Here is an easy tutorial on how to build your own dyno for your radio control cars and trucks. All you need is a computer, cheap headphones and the free software called SimpleDyno.

Basic principle is a small magnet fixed to a rotating item (e.g. tire, dyno roller). Then a sensor that senses the magnet everytime it rotates by the sensor. This creates a signal that is inputted to the computer via the microphone plug, and graphically plotted by the SimpleDyno software.

You can get rpms, torque, speed and power reading graphically. This is a great tuning aid to help you choose gear ratios and select the best motor.

How to Build the RC Car Dyno

1. Download the SimpleDyno software and install on your computer. Read the instructions from the SimpleDyno website. Then tune the parameters to suit your needs.

2. Get a headphone for computers.

3. Break one of the earphone to get the small magnet.

Cheap RC Dyno

4. Attach this magnet to your tire or roller (dyno).

RC Car Dynamometer How to Make

Photo: The rc car dyno. The magnet, headphone (sensor) and f103 pod with tires (to act as dyno rollers). The slave motor acts as a dummy load to the dyno to get more accurate speed readings.

5. The other earphone (still intact) is mounted about 5mm away from the small magnet. This will be the sensor.

Cheap RC Car Dynomometer and Motor Checker

Photo: Cheap motor checker. Attach the magnet directly to your rc cars tire and check for rpms. More rpms usually means better motor and faster speeds.

6. Attach the headphone to the microphone input of your computer.

Turn on your remote control car, then accelerate. You can use the software to either display RPM, Speed, Power or Torque. Great stuff and best of all this software is free.

RC Car Dyno Video

Here you will see a Tamiya F1 and M-chassis mini rc car on a dyno roller made from an old Tamiya F103 rear pod. The second part will show that you can directly attach the magnet to your rc cars tire, then simply hold the headphone near it. This can then give you wheel rpms and allow you to test the speed and power of your motors easily (i.e. very cheap electric motor checker).

Dyno Software Tip:

1. To get clean signals, there is a Signal Threshold parameter, tune this so that the green line (baseline) is slightly below the red line (the headphone sound line). I set mine to around 60.

2. You will need to play around with the software parameters to get readings that would approximate real life. But it's easy.

Sample Dyno Results

Using this cheap home made rc dyno, I compared my Tamiya F103 and Tamiya M05 mini rc cars. Here the F1 is twice as fast.

Car Motor RPM Speed
Tamiya F1 11,339 26mph
Tamiya Mini 6,367 13mph

You can then change motors and gearing and tune your car to gain a competitive advantage against your friends and racers.

Hope you enjoyed this tutorial. Please share this with your friends and come back again for more rc car tips.

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