Hi i just started engineering in electricity, I come from a French school and I wanted to know what does "to fine-tune a circuit" mean someone just explain this to me in basic english thx Semi-fixed resistors are used to compensate for the inaccuracies of the resistors, and to fine-tune a circuit. The rotation angle of the variable resistor is usually about 300 degrees. Some variable resistors must be turned many times to use the whole range of resistance they offer. This allows for very precise adjustments of their value. These are called "Potentiometers" or "Trimmer Potentiometers."