Slide potentiometer

The 45 mm slide potentiometer off a mixing desk: the same carbon track as the rotary potentiometer, laid out straight with a knob you push along it.

Three pins: 1 at the bottom of the travel, 2 the wiper, 3 at the top. Kit fader modules bring the track out exactly this way, with nothing else on the board.

Pins

Pin	What it does
1	The bottom of the travel.
2	The wiper.
3	The top of the travel.

Properties

value: the track resistance in ohms, 10 000 by default, as the modules come.

While it runs

Drag the knob along the slot on the canvas.

What the model gets right

Electrically it is the same track model as the rotary pot: R x f from pin 1, R x (1 - f) from pin 3, and a source impedance of R x f x (1 - f) at the wiper, zero at either end of travel. There is no third element and no special case for a rheostat wiring; both fall straight out of the two resistors. The travel here is linear, unlike the rotary pot, because that is how the kit fader modules are built.

What it does not model

No audio taper. A fader with a proper audio law is a real thing on some mixing desks, but the module a kit ships with is linear, and taper lives on the rotary potentiometer instead.

Everything the rotary pot leaves out is left out here too: an ideal track with no wiper contact resistance, no end resistance, no tolerance on the value, no temperature coefficient, no noise and no scratchiness, and a position that is a clean 0 to 1023 with no jitter in it.

Common mistakes

Expecting a taper property the way the rotary pot has one. A slide pot in a kit is always linear, so there is nothing to set.

See it in action

Servo fader uses the slide pot to set a servo's angle live. Open it at /templates.