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Topic: Help me breadboard a cabled remote control (Read 2159 times) previous topic - next topic



I would like to replace the cable-connected remote control of a directional motor by a breadboard controlled by the arduino. Here is what the cable / remote control does:

And here is the inside of the remote:

The resistor at the back is on the +5V and is to the best of my knowledge a 3.9K. (color coding - and I also get this value when measuring, but in-circuit).
It seems to be a 20K sliding pot at the bottom and indeed when measure I get variations from 0 to 23K. This items controls speed on the remote control and is connecting the speed cable to ground.

When on the motor that this remote controls I plug a 0ohm resistor between +5V and and direction it works (but gets VERY hot after a very short while... I only discovered the 3.9K resistor later). Between +5V and speed the resistor starts smoking.  :smiley-mr-green:

So: how do I reproduce this remote control on a breadboard to work with the arduino?

I am thinking: for the directional controls :
digital pin 1 --- transistor base
                                          Emitter / Controller to +5V / left cable with a 3.9K resistor in the circuit
etc for the other 3 directions
... but what about the ground cable? What's that for? And how do I control speed (the 20K pot)? Is this a completely different and independant circuit? Is there a way to have a digital equivalent of the 20K pot effect?

oh - the remote has no battery. all its power comes from the motor.

Thanks for nay help!


Or maybe I could use a 595 shift register instead of the transistors?


If you wanted to use optoisolaters (4N35), I have a design for you. This board design was created using Fritzing http://fritzing.org/.

I have not written the code for it yet, but here are the basics:

A0 = Speed inout
D2 = Up input
D3 = Down input
D4 = Left input
D5 = Right input

D6 = Down out
D7 = Up out
D8 = Right out
D9 = Left out
D10 = Speed out

I'm not sure what happened to the outputs, I'm tired, but they would just need to be rearranged. I will do up a new board tomorrow when I'm awake. I will also write some basic code for you.

Hope this helps.




Excellent work - many thanks! (Sorry for the late reply on my side - I was travelling).

Yes - I was also thinking about using the optoisolators - at least I understand optoisolators and I can say the same for transistors :)

Are these 10K resistors you have on the left of your diagram, connecting to the optos?

No need to help me with the code - that the easier part. Thanks a lot for offering though!!!

Do you have an idea though on how to replace the manual 20K pot with a digitally controller variable resistor (even if it only has 4 steps - ie: 0K, 7K, 14K, 20K). For instance digital pin 5 triggers a 7K resistor on this circuit, pin 6 14K, pin 7 20K ?

Well done,



One thing I noticed in your diagram is that you put the POT between 5V and ground - it instead needs to be between the red and purple cable at the top. Still searching for a way though to do without the pot and have a digital-controlled equivalent.


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