Potentiometers - which is best.

[Fall_guy]

Hi Guys,   how ya all do'in

Just wondered if theres any difference between using a SLIDE Potentiometer and a ROTARY one for use in a THROTTLE build.

Any advantages or dis-advantages would be a great help.

Many Thanks
John

[matta757]

John,

I am using rotary pots on my throttle. I see the merits for both. I guess the one thing you need to be sure about with rotaries is how you plan to turn them, for instance, I am using gears and I had to make sure to get the right ratio. My pots move 270 degrees, but the throttles are only moving about 90 degrees, so I am using something like a 3-1 ratio on my gears. This works well for giving accuracy within the game.

The nice thing about slide pots is that you don't need to worry about gears. Had I not committed to the rotaries, I have actually thought that using slide pots might have been easier. I know Jack (jackpilot) used slide pots on his TQ, so he'd be the one to tell you how it works best!

Matt

[Flying_Fox]

I am using gears and I had to make sure to get the right ratio. My pots move 270 degrees, but the throttles are only moving about 90 degrees, so I am using something like a 3-1 ratio on my gears.
Matt

Hi Matt,

Just wondering about your gears. Did you buy or make them? What material? How did you fix them on the shafts?

Thanks,
Nick

[matta757]

Nick,

I bought them from Servocity.com. I opted for the plastic gears, although you might consider metal if you can afford it. My gears fit nice and snug on the shafts of my pots, so I didn't have to come up with any attachment method.

Matt

[jackpilot]

Hey Matt ....
Yep Sliders ,sliders, sliders.  Phidgets to name it.
No gears just a little rod made out of hanger wire.
Check my posts on the TQ

The end result is that Phidgets+ FDS FC1 card = Both throttles within less than 1% all the time.
No need for FSUIPC sync.

[Flying_Fox]

Nick,

I bought them from Servocity.com. I opted for the plastic gears, although you might consider metal if you can afford it. My gears fit nice and snug on the shafts of my pots, so I didn't have to come up with any attachment method.

Matt

Thanks for the info Matt!

Nick

[NeoMorph]

One question... do you guys use standard pots or "High Precision" versions? One thing I hate about standard pots is that they tend to cause the A/D circuits to flip between values causing all sorts of weird outputs (the ones in the Saitek Yoke are pretty damned awful for that). I've also seen them throw out weird out of range values when the pot is getting worn... something I never saw in the high precision verisions. Then there is the decision to use wirewound or carbon tracks... decisions, decisions. Some people prefer wirewound while others prefer carbon.

I'm actually going to be running some tests next week when my high precision pots come in just to see if there is a better accuracy seen within FSX. It might not actually make that much difference other than the lifetime of the pots in question.

Oh and personally I hate sliding pots... mainly because the ones I used to use were the ones that threw out the out-of-range values after time. You end up having to move the things back and forward several times just to clean the contacts... but this was back in the 90's so the build quality may have improved now.

One final thing... MAKE SURE THEY ARE LINEAR... It's too easy to try using logarithmic pots and wonder why they won't calibrate right (been there, done that trying to make a racing car setup for a friend of mine... he got the pots for the steering and couldn't figure out why it turned slowly to the left but fast to the right... My fault for not checking heh).

[Fall_guy]

Hi there,

Thanks for the info Matt. a big help.

I was actually thinking of using SLIDE pots (because of their simplicity no gears to fit) but was'nt quite sure how accurate or reliable they would be.

Jack................. are these prone to clog-up after a while?

Thanks again for all your help and advice

John

[jackpilot]

Phidgets Linear are used by FDS
They wouldnt if they were unreliable.
Personnaly no prob with them.
On my first TQ I was using Top quality Ceramic pots but despite that I was not able to get throttle sync. (Gearing has to be top quality too.)
My 2¢: No gearing /Top sliders  /  hi resolution card.
Winning combo... for me at least.

http://www.phidgets.com/products.php?category=7&product_id=1112

[Fall_guy]

Thanks Jack

John

[727737Nut]

Technically,  it depends on what throttle you are interfacing and how it is made.  If using a real throttle, slidepot's don't work.  If using a homemade assembly then it could be designed to use them.  See, a properly made throttle that mimics the real movement would require a slide pot length of 10" to get TRUE LINEAR response.  Only way to accomplish that is using string pots.   I have interfaced 3 real throttle assemblys and one homemade one. I have used slide pots, regular pots, and string pots.  No question at all, string pots are thee way to go if you want true movement, repeatability, and staying in 'sync' as you say.    Just like any mechanical moving part, the pot's will eventually wear out and will need replaced.  If your area is dirty,  it will be an issue eventually.
Just my humble .02 worth.

Rob

[Vectro]

this is also very pro, for example for throttles and rudder pedals.
http://www.lentosimulaattori.1g.fi/kuvat/assorted+construction+pictures/throttle+and+controls/simukaasut+003.jpg

[NeoMorph]

For a GA aircraft, slide pots are the way to go as they mimic a slide anyway. Heavier aircraft are rotary based and I would have thought rotaries would be the answer for all. It's quite amazing how many different solutions there are for the same problem.