Metal cover (B10K)Plastic bodyThreaded bushing · M7 × 0.75Knurled shaft · Ø 6 mmPins 1-2-3 (middle = wiper) · 5 mm spacing

Metal body, knurled shaft, three legs on the bottom edge and body mounting tabs
Body diameter ≈ 16 mm, shaft diameter ≈ 6 mm

Resistors

Potentiometer

In simple terms

What is this?

Like a tap you turn by hand; the more you turn, the more or less flow passes.

What is it for?

Lets you adjust volume, brightness or speed by hand.

Where do you see it?

In a speaker's volume knob and in the knobs of a guitar amp.

How do you spot it?

A round box with a rotating shaft in the middle, a turning knob on top and three legs underneath.

Caution:

At zero, no resistance is left; still put a fixed resistor in front of a part like an LED.

Technical definition

A variable resistor in which a turning shaft carries a sliding contact (wiper) over a resistive track. The resistance between the two outer pins is fixed; the resistance between the middle pin and the ends changes as the shaft turns. It is mostly used as a voltage divider.

Value10 kΩ

CurveB (linear) · A (log)

Tolerance±20%

Schematic symbol IEC and ANSI differ

IEC 60617: the drawing style used in Türkiye and Europe.

Pins 3

1Terminal 1With the shaft facing you, the left leg at the bottom; usually GND1

2Wiper (middle)As the shaft turns it slides along the track; the output is taken from hereW

3Terminal 3Right one; turning clockwise moves the wiper toward this end, usually VCC3

Features typical

Value: 1 kΩ – 1 MΩ (10 kΩ common)
Tolerance: ±20%
Curve: B = linear, A = logarithmic
Rotation angle: ≈300°
Power: Low, usually under 0.5 W
Track: Carbon · cermet · conductive plastic
Example part: 16 mm rotary pot, B10K

Common mistakes

Current limit set to zeroIf you put a pot in series with an LED on its own, no resistance is left at the zero position and the LED burns out. Add a fixed resistor in series with the pot.

Passing load current through the wiperThe wiper is a tiny contact point; it cannot carry motor or lamp current. Drive the load with a transistor and let the pot only set the level.

Mixing up A and BFor volume control choose A (log), for sensors and dividers B (linear). On the wrong taper most of the adjustment bunches up at one end.

Test with a multimeter

Test whether this part is good with the multimeter on the measurement screen.

Take a measurement

Where it is used

Volume adjustmentLED brightness inputAdjustable voltage dividerMotor speed input

Try it in the Lab