Linear potentiometers instead of 9 position switches?

[Chris Wilson]

I have made a couple of rotary switches with 220 ohm resistors between each terminal, and between each end terminal and 0 volts and 5 volts. These work fine, but are fiddly to make if using small switches. Is there any way I can use a linear potentiometer, and a knob scale? How would one read the values in the calibration table, just read max and min and let the software interpolate? Any gotchas? Suggested value for the resistance of the pot? Thanks.

[Allan L]

without a positive detent to hold a position i would be concerned about using it for anything critical!

[stevieturbo]

DTA recommend a linear 10 turn 10k pot for their TCS setup.

And positioning is sorted using one of these. Infinitely variable, but also easy to accurately position. One show is a 20 turn, so I guess best used with a 20 turn pot ?

http://www.potentiometers.com/MG22.cfm

[Chris Wilson]

Thanks Stevieturbo. Would the "read sensor" function be happy with such a device? To be honest a multi turn device is probably a bit OTT, I would be happy with a single turn with a dial knob and scale.

I see where you are coming from with the device moving position Allan L, but I can introduce friction on the underside of the dial, and this is going in a road car anyway, I can't recall the radio volume knobs or other pot type controls ever moving themselves in any road car I have owned. I would be much more cautious if were an off road / race type vehicle, thanks for the warning though, appreciated.

[stevieturbo]

Thanks Stevieturbo. Would the "read sensor" function be happy with such a device? To be honest a multi turn device is probably a bit OTT, I would be happy with a single turn with a dial knob and scale.

I see where you are coming from with the device moving position Allan L, but I can introduce friction on the underside of the dial, and this is going in a road car anyway, I can't recall the radio volume knobs or other pot type controls ever moving themselves in any road car I have owned. I would be much more cautious if were an off road / race type vehicle, thanks for the warning though, appreciated.

The little dial I showed has a simple lock on it. When set it cannot turn. It's actually a really easy thing to use, and the rotary dial gives accurate positioning

And depends what you're using the input for and how the ecu interprets it. If it's for a Cal switch which I suspect, I see no reason why it wouldnt work, as you calibrate each setting to a particular resistance ?
The changeover point may not be as instant as the normal rotary switch...or maybe it will ?
Whilst I have one of those ecu's here, Ive still never used it yet myself, so cant comment on how easy it would be or how well it would work..