Cheap potentiometers for Sim cockpit

[TripRodriguez]

Hey guys! I need 18 potentiometers for what I'd call "minor" functions in my sim cockpit. These will be connected to Teensyduino and Leo Bodnar boards to control things like brightness of instrument lights etc.

 

I have a bunch of audio potentiometers but I read somewhere (Leo Bodnar site maybe?) that they should be avoided.

 

So here is the question, should I indeed avoid using these audio pots, and if so how do I avoid getting the audio type variety when I shop for cheap potentiometers?

 

I've spent some time on ebay just now, and keep finding in the fine print that the pots I'm looking at are "good for audio equipment" and such.

 

Thanks for any help

[FragBum]

Hi TR okay here's a potentiometers 101

 

 

A pot for say audio volume control has a log law transfer characteristic which mean the amount of resistance change for rotational angle is not linear.

 

On the other hand a pot with a linear characteristic has a more or less linear change in resistance for a given amount of rotation. e.g. on a linear pot setting the rotation to centre will give pretty much half the resistance on the wiper contact. 500R for a 1000r pot. "B" curve.

 

The problem of using a pot with a log type curve (pot suited to audio applications) is all the control action will be in a small portion of the rotation of the pot with pretty much nothing happening for the rest of the shaft rotation.

 

You could put a resistor of about the same value in parallel with the wiper and the top connection of a log type pot and it will be sort of linear but better to look for "B" type curve pots.

 

More info here

 

Now you may actually want to alter the taper (transfer curve) of a pot to give a "feel" for what it's controlling so that link maybe helpful. I used to do that for model train controllers but found better ways of doing that now days.

 

Your project sounds interesting however.

[Sokol1_br]

.. how do I avoid getting the audio type variety when I shop for cheap potentiometers?

 

Look for LINEAR potentiometer, B code, example B10K

 

http://www.ebay.com/itm/10pcs-B10K-Ohm-10K-Shaft-3-Pin-Linear-Rotary-Taper-Adjustment-Potentiometer-Pot-/331908309234?hash=item4d4746e0f2:g:dMwAAOSwGXtXhxqs

 

http://www.ebay.com/itm/6Pcs-Type-B-10K-ohm-6mm-Knurled-Shaft-Single-Linear-Rotary-Taper-Potentiometer-/322381852785?hash=item4b0f74b071:g:oloAAOSwa~BYb6IG

 

In BU0836 you can use ~10 to 100k pot's.

 

10 K give a more clear signal for USB controller, but consume more amperage

100 K give a more "noise" signal for USB controller, but consume less amperage

 

Since you plan use many, 50K seems a good compromise.

 

BTW - DO a test with this audio pot, depend on function controlled can be usable.

[Thadiun Okona]

Don't buy 'cheap' pots, buy 'inexpensive' ones. Shop ebay for 'sealed' 'linear' pots made by Bournes, Vishay, Spectrol, Watts, or anything Mil Spec.

 

You probably also want 'panel mount' (threaded collar to mount through holes in panels), and shafts will be determined by your knobs but most will be 1/4 or 1/8", with or without a flat.

[FSFIan]

10 K give a more clear signal for USB controller, but consume more amperage

100 K give a more "noise" signal for USB controller, but consume less amperage

 

Since you plan use many, 50K seems a good compromise.

 

You can (and should) use 10K or even 1K for every potentiometer. A 10K pot will only draw 0.5 mA (given the 5V supply voltage of the Leo Bodnar board), a 1K pot will draw 5 mA.

 

As long as you stay below 500 mA for the entire board (not allowed to draw more than that from USB), you should be fine.

[TripRodriguez]

Thanks guys. I guess I was barking up the right tree after all, I was looking at "b type" "linear" pots but in the descriptions they kept mentioning audio usage so I started thinking there was more I didn't know.

 

@Thadiun_Okona I'll take a look, but due to the sheer number of pots I need I'm trying to keep it to ~$2 per pot or less, preferably more like $1 per pot. These again are for non critical functions such as instrument panel and nav light brightness etc.

 

Not for aiming or flying =P

[Sokol1_br]

... due to the sheer number of pots I need I'm trying to keep it to ~$2 per pot or less, preferably more like $1 per pot. These again are for non critical functions such as instrument panel and nav light brightness etc.

 

This brands suggested by T.Okona will cost more than 3$ per unity.

 

Using cheap think in assembly the pot in way that make easy replace then if (when) fail (spikes).

[TripRodriguez]

This brands suggested by T.Okona will cost more than 3$ per unity.

 

Using cheap think in assembly the pot in way that make easy replace then if (when) fail (spikes).

 

Yes, replacing them will be very easy when needed.