Potentiometer

Problem

Slide Potentiometer			Knob Potentiometer

Solution

• The high side (red) into a VIn set to 3.3V.  This is the default voltage for the inputs, so if you haven't touched it, you can screw into VIn1.  Otherwise, set the voltage on your inputs back to 3.3V.
• The low side (black) into a GND on the Make Controller.
• Signal (yellow) into an Analog In - In0 on the diagram below.  The voltage of the signal will span from 0V to whatever voltage you put on the high side - we chose 3.3V since that's the level the inputs on the Make Controller Kit are expecting.
  

Discussion

When you turn a potentiometer, you're actually sliding a contact (the wiper) along the pot's resistive element, changing the resistance to the electricity flowing between the high and low sides of the pot.

Figure Out Which Wires Are Which

If you don't already know which wire on your pot is which, the first step is to figure out which is the wiper.  The other two connections can be wired in either orientation between 3.3V and GND - swapping these, however, will change whether the resulting voltage goes up or down as you turn the pot in a given direction.  It's usually desirable for the voltage to get higher as you turn to the right - think volume knob - so we'll work with that configuration for this guide. 

Take your multimeter, and set it to measure resistance.  We'll utilize the trusty trial and error method to conduct our investigation.  Here are a couple of the possible results you might find, and how to interpret them:

• Very high resistance (in the megaohm ballpark) between 2 leads - this means you're connected between the high and low sides of the pot.  The high resistance means there's no connection, which is good since that would be a short.
• A resistance between 0 and 10K ohms - each pot will have a given maximum resistance.  The pots we sell at MakingThings are 10K, so I'll use that here, but this value will vary from pot to pot.  If you make this connection and turn the pot to the right, observe how the resistance changes.  If the resistance goes down, the resulting voltage would be higher, meaning you're connected between the signal and the high side.  If the resistance goes up, you're connected between the signal and the low side.
  

Often, on rotational pots the signal is in the middle, so that's as good a place to start as any.

Testing

It's a good idea to test any device you've wired yourself before hooking it up to the board. Once you've determined which leads are which, the following steps will confirm that you've wired it up correctly:

• Connect the pot as described above, but leave the signal wire disconnected.
  

• Put the negative probe of the multimeter on a GND on the board, and put the positive probe of the multimeter on the signal wire.  If you're getting readings between 0 and 3.3V, you're all set!  If not, go back and double check your resistance tests.