I've been searching for days and still have not come up with an answer.

What is this symbol?:

enter image description here

The component in question was found on this mosfet amplifier schematic from the 1980s.


2 Answers 2


This looks like preset potentiometer wired as rheostat. Here you can find the following definitions: enter image description here


Long story short: It's a variable resistor. Mainly used as a preset resistor (e.g. to equalize an DC offset)

See Rapidtables as an example and search for "Trimmer Resistor" after maybe 1/3 of the page.

  • \$\begingroup\$ Aw! Please can we have the long story? \$\endgroup\$
    – Transistor
    Mar 6, 2018 at 19:02

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