Potentiometer 5 or 6 detents

[Alan Anderson]

Originally Posted by Adam Shapiro

The idea here isn't as much the actual resistance as the concept...

If the switch is going on the OI, the actual resistance is rather important. The OI analog inputs want to see a variable resistance between ~2k and 100k to give the full range of values.

For a six-position rotary switch, I'd use six 15k resistors wired like this:

+5 <----/\/\/--*--/\/\/--*--/\/\/--*--/\/\/--*--/\/\/--*--/\/\/--*
                         ^
 OI                      |
analog input <-----------'

The * characters represent the six positions of the rotary switch, and the ^ is the common connection.

What you'll get from this is the equivalent of a joystick with six discrete resistance values: 15k, 30k, 45k, 60k, 75k, and 90k. You should use a dashboard program to determine what the actual numbers end up being, and choose appropriate ranges in the software to decide which of the six positions is chosen.

[Adam Shapiro]

Originally Posted by Alan Anderson

If the switch is going on the OI, the actual resistance is rather important. The OI analog inputs want to see a variable resistance between ~2k and 100k to give the full range of values.

I actually never knew that, though in retrospect I suppose it makes sense. Thanks for the clarification!

[Tom Bottiglieri]

I see a business opportunity for Andy Mark/IFI! Latching potentiometers/ prewired variable resistance rotary switches!

Travis,

I thoroughly googled for a pre-made product that would suit your needs but came up with nothing. The best solution in this thread is Alan Anderson's, which is exactly the method I was going to post before I saw his.

I'd check to see if any of the students on your team are taking/have taken electronics classes at school. If so, you can just buy a rotary switch and some 15 Ohm resistors (if you need more inputs, decrease the Ohm rating of the resistor. What you want = 100 / Number Of Switch Settings + 1. Get all of this stuff at RadioShack) and give it to the student to wire up. Anyone with basic knowledge in wiring should be able to tackle this circuit.

[Joe Ross]

Originally Posted by Tom Bottiglieri

I thoroughly googled for a pre-made product that would suit your needs but came up with nothing. The best solution in this thread is Alan Anderson's, which is exactly the method I was going to post before I saw his.

I found the Bourns 3680 series. However, it is very expensive. http://www.mouser.com/catalog/625/505.pdf

[sanddrag]

In past years we had like three two position switches and we would have a setting like (up down up) or (off off on) for the switches before each match depending on what autonomous mode we were going to run. But such things could get confusing in the rush of competition, and I see your desire for the rotary type control.

[Travis Covington]

The potentiometer I found on digikey seems like it will work, but as Joe told me, is an SMD style and would require some delicate soldering. I think I can handle the soldering, but is there any reason not to use this pot?

http://dkc3.digikey.com/PDF/T061/SectF.pdf

Page 74, 16mm square rotary potentiometer with detents.

Also, I think I can handle the rotary switch and 15k resistor method as well. I think mounting the rotary switch and a knob will be easier than the pot with detents and no shaft with a make shift shaft and knob.

Edit: How would that diagram differ if I put the rotary switch/resistor setup on the RC?

[Alan Anderson]

Originally Posted by Travis Covington

...How would that diagram differ if I put the rotary switch/resistor setup on the RC?

Just add another resistor to ground on the far right, just like the one to +5 on the left. (On the RC, you could actually make the +5 and ground connections directly without resistors, but I'm used to being able to detect short circuits as "impossible" input values.)