What is this schematic symbol please?

[Dud]

Schematics (understanding and drawing them)

To enrich the Glossary links a little Potentiometer : [potentiometer]

Schematics (understanding and drawing them)

It’s the symbol for a “variable resistor,” which (for low power requirements (*)) is realized as a potentiometer with one lead connected to the wiper and the other to one of the ends. It’s common to connect the wiper to the other end while you’re at it: [image] but that’s mostly to avoid dangling leads (and if you use PCB-mounted potentiometers, you want to solder all pins for physical stability). (in this circuit, the resistance controls how quickly the 2.2u capacitor discharges) *) EDIT:…