CHAPTER 14 ■ VARIABLE RESISTORSTurning the Dial
Most potentiometers have single-turn dials. That is, they rotate from their minimum value (0 W) to their
maximum value (printed on the case) within one rotation of the dial. With only a single rotation, you can
quickly change the value and you can easily tell by the dial angle when the potentiometer is at the beginning,
middle, or ending of its range.
Multiturn potentiometers (see Figure 14-4) take many turns (25, for example) to adjust through their
entire range. This makes it possible to fine-tune an exact value, since each twist of the screwdriver only
tweaks the resistance a little bit. Also, if the dial slips a little bit on its own due to vibration or temperature
changes, a multiturn potentiometer changes value less than a single turn potentiometer.
Figure 14-3. Adjusting Sandwich’s trimpot with a flathead screwdriver through an access hole
Figure 14-4. A breadboard-compatible multiturn trimpot