10K THUMBWHEEL POTENTIOMETER as a volume control?

Hi,

I have a 10K Thumbwheel potentiometer and I would like to use it as a volume control for tones from an Arduino pin to a small speaker.

Right now I am going from the pin with a resistor to a 16 ohm, 0.5W mini speaker. I would like to replace the resistor with the potentiometer to adjust the volume but I haven't been able to find any info on it to know which pins do what.

Has anyone used this 10k pot?

You need a minimum resistance of around 125 Ohms including the speaker impedance so if use a pot you should also have the resistor. 10K is way too much for a regular 4 or 8 Ohm speaker.

DVDdoug:
You need a minimum resistance of around 125 Ohms including the speaker impedance so if use a pot you should also have the resistor. 10K is way too much for a regular 4 or 8 Ohm speaker.

Thank you DVDdoug for taking the time to help. For future reference, if I need this pot in a project, I would like to know which pins are which and how to hook it up.

By “which pins do what”, do you mean the pins on the potentiometer? If so, of the three pins in a row, the two outside pins are the “ends” of the 10K ohm resistor. The center pin, and the pin in the center of the disc, are connected to a wiper that moves along that 10K resistor. In the center of motion, if it is a “linear” potentiometer (the seller does not say), the resistance from the center pin to either end will be 5K ohms. The other kind of potentiometer, the kind usually incorporated in audio control circuits, has what is called a logarithmic taper (because our ears respond logarithmically to changes in perceived loudness). But either linear or logarithmic taper can work.

It is not a usual way to control speaker volume by placing a resistor in series with a speaker. This is because that vastly reduces the efficiency of the speaker because of impedance mis-match between the amplifier output impedance and the speaker impedance. But it can work, because here you are not adjusting the gain of an amplifier. You are only changing the amplitude of a pulse-width-modulated 5-volt power source. But you might find that a 10K potentiometer is too high a value. You might have very little effective range of adjustment, with only useful adjustment being in a very small range at one end of the rotation. A 100 ohm or 1000 ohm potentiometer might work better, but I am only guessing.

You connect your speaker to either of the outside pins. It doesn’t matter which, except to change the direction of rotation for increasing or decreasing volume. You connect the center pin to either the Arduino pin, or ground. It does not matter which. It can be the other way around also. As long as speaker and potentiometer are connected in series between Arduino pin and ground, several different configurations work the same.

You might find it useful to buy or borrow a very low cost volt-ohm meter to measure resistance and to more clearly understand. Don’t forget the fixed resistor that Doug mentions or you can damage the Arduino with almost a short circuit between the pin 5-volts and ground when the potentiometer is adjusted for zero resistance.

There are tone() libraries with digital volume.
I suppose you can control that volume with a digitalRead value from a 10k lin pot.
Leo..

Thank you Johncfii for your detailed and extremely helpful answer, your help is very much appreciated. :slight_smile:

Also thanks to DVDdoug and Wawa for having the patience and kindness to try to help an obvious beginner.

Cheers!