View Full Version : What kind of POT?

02-05-2008, 08:29 AM
I have the Hagstrom USB 108 interface which has Joystick inputs....

Joystick Analog Inputs

Three analog inputs are provided on the KE-USB108 to allow for potentiometer usage for joystick X, Y, and Z axis controls. Connect any potentiometer from 10K to 1M resistance values to the KE-USB108 to produce action on the desired joystick axis. The individual axes may be enabled or disabled allowing for the use of any or all of the joystick axis inputs.

I see that it says 10K to 1M resistance and not sure what that means but my objective is to create my own trim wheel (for GA aircraft) and hook it to a pot and interface it through the Hagi. Does this sound like the right way to add a trim wheel and if so is there a specific type POT that someone could suggest as I have never interfaced pots...only switches thusfar.


02-05-2008, 12:02 PM
HI there,

10k means 10000 ohms
1M means 1000000 ohms
100k is quite a standard value for potmeters. There are even potmeters which need 5 or 10
full turns for the full travel from 0 ohms to 100k ohms (linear) which are I think a good solution for the trim of a ga airplane

Greetz Peter

02-05-2008, 07:08 PM

Looked at Radio Shack and found a 100K-Ohm Linear-Taper (250VDC - .25W) 1 Turn

Would this be appropriate?

02-06-2008, 07:47 AM

that could work if you want to turn you're trim only one turn for the full range ...

Greetz Peter

02-06-2008, 07:49 AM
Just looked again and in reality it is only 300 degrees. That wont be very realistic. Probably need to find one that is 10 turn.

Anybody have a good electronic supply company in the US Midwest?

02-06-2008, 07:58 AM
There is a on-line electronics company I have used that is good. They even have technical support for help choosing what you need.


02-06-2008, 08:24 AM
I would suggest avoiding taper or logarithmic pots, these are more for hifi volume controls etc. For sim controls you need linear pots, slide or rotary.


02-06-2008, 11:44 AM
Jameco (www.jameco.com (http://www.jameco.com)) is a California electronics supplier you might consider. They have a 10-turn 20Kohm pot that should do. (Jameco part #771163) I like Jameco because they often have the lowest price on small quantity orders.

Digikey (www.digikey.com (http://www.digikey.com)) is another option.

Potentiometer background info: http://www.mikesflightdeck.com/potentiometers.htm

02-07-2008, 08:17 AM
Thanks guys. I actually got lucky and found a company in the US Midwest that is about 15 miles from my office! Tri-State Electronics. They have a pot that looks just like what I need.


02-07-2008, 09:39 AM
I'm about to start on my center console so I'm looking into what would work best for the trim wheel. In real GA a/c the trim wheel rotates many times so using a normal pot seems too unrealistic. You will need to incorporate some gearing so that you can turn the pot fewer turns per trim wheel rotation.

I'm going to try to use a component (cord operated tilter) found in 50mm venetian blinds. This is the component that tilts the slats when you pull on the cord. http://www.windowblindsparts.com/ComponentPics/lpctpw.jpg . It's basically a 90 degree gear with a plastic spool on the end of it. Nice thing is that it is encased, compact and simple as opposed to external gearing. Only about AUS$15 from blind parts stores. It will take minor modification (mounting holes and some work attaching the trim wheel and pot etc) but the nice thing about it is that the reduction gearing seems quite realistic. I'll be working on this shortly to see if in fact it will work as well as anticipated.


02-07-2008, 01:21 PM
Interesting Idea

That is why I was going to go with a 10-Turn Pot. It would be a lot more realistic and probably wont need any special gearing.

02-11-2008, 07:40 AM
Well, I tried a 10-Turn 100K Ohm linear and it didnt work out. It was very jumpy and would not allow the trim to be adjusted properly. It was not smooth like I thought it would be but rather would tend to jump all over the place. Made for a wild ride! I tried calibrating it a number of times using both FSUIPC calibration as well as Windows but to no avail. $15.00 down the drain.

I ended up puting in a $3 Radio shack 100K Ohm Linear Taper 300 degree pot and it works perfectly. Obviously doesnt work identical to real thing but close enough. I may try gearing it down.