Need help with parts in a RC hand controller.

[h3ro]

Today I have been playing with my old RC radio that did not work. It was nothing seriously wrong with it, just something with the battery connection.
My idea was that maybe it would be possible to connect the right/left and back/forward controls to a parallel port.

But, where can I find some information about how the controllers in the radio work? I have tried to measure the it with a voltmeter to see how it changes when I use them, but I am still not sure how they really work.

As the right word for the things I am trying to find out how work probably isn't controllers I have attached a picture.

[h3ro]

Ok, I have found out how they work and what they are. Its some form of manual speed control which controls how much voltages runs through the curcit. (right?)

Is there a way so I can make a simple digital version of the "manual speed controller"? Maybe without the use of a microcontroller? Keep in mind it will be connected to the parallel port.

The only way I can think of is to make some engines drive the manual speed control, but I assume there is a better way to do it?

[Admin]

Keep in mind it will be connected to the parallel port.

Could you explain more on what you need it to do?

So that trigger is connected to a potentiometer, which changes a voltage. This means you will need a circuit that can detect this voltage, and convert that into something that can be sent down the parallel port. Personally, Id use a microcontroller

[h3ro]

Thank you for your reply Admin

I dont need to know the voltage, I only need to modify it, so I can control the signals from the RC controller from the parallel port.

I think I have found a easy way to do it:
I am going to replace the potentiometer with a small circuit with two relays. They will work like this:
   Both off - Sending 0v through where the potentiometer was before. This will make the servo reverse.
   A On - Sending 1.5V through where the potentiometer was before. Will make the servo stand at default / zero.
   B On - Sending 3V through where the potentiometer was before. Will make the servo move in the positive direction.

(The above is not the right voltage!)

And here is a very professional circuit drawing:


Anyone know if a setup like that will work? It does in my mind

[Admin]

Wait, are you trying to control a servo?
(if so, this wont work)

If you are trying to control a DC motor, you want either an H-Bridge or motor driver.
(just search those on this site for tons of info)

You might be best off just buying a servo controller that connects to your PC.

[h3ro]

Im not trying to control a servo, at least not directly.

What I am trying to do is to replace the potentiometer with something that I can control through the parallel port. If I use the setup posted above I think that I can make the RC controller send the signals I want it to.

If I use the trigger(red arrow on the first picture) I get full speed on the servo. I get the same effect if I keep the trigger at default, but attach a extra 1.5V battery to it.

So basically removing the potentiometer and are replacing it with a small circuit which can operate at 0V (reverse), 1.5V (default) and 3V (forward).

Hope it make some kind of sense.