Potentiometer on Parallel Port?

Is there anyway I can hook up a potentiometer I have the the parallel port of my desktop pc? I’ve been trying to find wiring diagrams but haven’t had any luck with :frowning:


The parallel port of your PC has 8 digital signal lines, and a bunch of control lines. It deals with ones and zeros. A potentiometer is an analog device, it deals with varying resistance. So, no you can’t just connect a potentiometer to a parallel port. You’d need an analog to digital converter, and then some circuitry and software that would make the converted number show up on the computer in a way you could use it.

I don’t know how to do it, but I do know it ain’t real easy.

what were you looking or hoping to do?


Oh, ok. I’m trying to make a throttle and rudder pedals that I can use with FS9.

Does anybody know of a good chip that would convert an analog signal from a pot into USB format? If I can’t use my empty parallel port I’d like to make it go through USB…


The easiest solution would be to get a sound card with a game port on it, and add that to the computer, and take apart a joystick or maybe one of the car racing pedal/steering setups and use the pots from it. I’m assuming you’re already using the game port on the computer for a joystick. Although I don’t know what’s up with USB game stuff these days, it’s probably taken over the old 15 pin game ports that I’m familiar with :slight_smile:

This is possible, but it is very very ugly. And when I say ugly, I mean that a Spartan mother would have left this solution on the side of the mountain.

You may remember this basic method from the days of PBASIC.

Take the pot and wire it such that its middle pin goes into one of the IO pins on the parallel port, and one of its other pins goes to the ground pin. Wire a capacitor in parallel with the pot.

Voila! You have an RC network whose time constant varies with the pot’s value.

Set the pin to an output. Wait a small while. Set the pin to an input, and time how long it takes for it to go from 1 to 0.

The reason this is not awesome is that you don’t have a great idea of exactly what voltage will cause a transition from 1 to 0. In fact, the spec for the parallel port probably doesn’t even say that it is repeatable.

However, you get what you paid for.

Enjoy and good luck!

I do know how to do this with a game port. But because almost no pc’s have them anymore, and every new pc has an abundance of USB ports I’d rather stick with that.

This guy accomplished what I’m trying to do: http://www.flightsim.com/cgi/kds?$=main/howto/mind.htm

Problem is I’m not very electronics savvy. I may just need to go with something like this: http://www.lbodnar.dsl.pipex.com/joystick/


Radioshack may have exactly what you need, and for only $5.

Plug this into your USB port, and now you have a game port interface, which is really easy to interface with switches and potentiometers.

That little USB-Game port adapter looks like a great solution! or see if you can find some old sound cards, they all have a game port on them too.

Anyone know the ADC specs on that USB converter? I think it might make a great (if laggy) DAQ… especially since it’s $5.


Sadly, anything with a 97 cent tag trailing the dollar amount is discontinued and will soon disappear in the annals of things you wish RadioShack still carried. If your store doesn’t have it, unless another one close to you does, chances are you won’t be finding one. Luckily, when I first saw these things go discount for $5.00, I bought 6 of them for $3.50 (Employee discount :p) and thus, if some of you guys need one it would be a matter of me putting it in a padded envelope and sending it to you.

Some things to know about it: It can only be configured to work with up to 8 buttons. It does work with Vista, and depending on what stick you use, it can have very high latency times. It also has trouble with store-bought wheels/rudders.

Not FIRST legal, but something to tinker around with in your spare time.\

Also, since 15 bucks isn’t that much, You could also look at these.


Like all the stuff in this catalog, which we used to read for hours on end (along with Lafayette, Heathkit, and Burnstein-Applebee catalogs)

I had a few of the Archer Kits in this Radio Shack catalog.

Well, I might end up going with this: http://www.lbodnar.dsl.pipex.com/joystick/

Since it can support a lot of devices, and seems very straightforward as to how to hook things up. I just wish I could build something like it for $5-10 bucks instead of $45 :frowning:

BTW, what does the Ohm rating on a potentiometer mean?


The ohm rating on a potentiometer (pot) is it’s resistance. All a pot is really is just a resistor with a center contact that you can move.

You can get pots with all different resistances, which one you want depends on the circuit you’re making. If you are going to use it to replace a joystick, then you’d probably want to use a pot with a resistance in the neighborhood of 10,000 to 100,000 (10k to 100k) ohms.

I’ll probably buy a gameport to USB adapter in the near future, but for now I found an old PCI card that has a gameport on it.

I’m having a little problem though. I hooked up two pots and two limit switches to the gameport, and installed it as a two-axis joystick with two buttons in control panel. But when I turn one of the pots all the way in one direction a dialog box pops up saying the controller cannot be found.

Why would windows say the joystick is unplugged when I turn the pot all the way in one direction?

I haven’t tested this yet, and won’t be able to until later tonight, but is it possible that the pots were set to full resistance and too little current got back to the gameport causing windows to say the joystick is unplugged?


Thanks for all the help guys. It’s working for the most part now. I hooked up the two pots to seperate 5v pins and it seems to work pretty well. I still get that disconnection error sometimes, but I probably just soldered a join badly or something…

Thanks again :slight_smile:

how would one get power for the IFI USB Chicklet. would i have to use a 7.2v back up battery and modify it so that the 2.1 mm female power jack is connected to the backup battery??

Give ya a hint:

  1. grab an ADC chip which can output 8 bits
  2. Wire it so that it will go into continuous conversion
  3. Wire up the input to your pot, 8 bit outputs to ur parallel port
  4. And you’re done :smiley: