Variable Capacitors...

[techo]

Is it just me or do most trimmer capacitors turn forever... is this normal? Maybe one half turn spans the whole range of capacitance and then if you keep turning it just goes back..
does anyone know the answer?

 

[Exo]

The capacitance will increase to its maximum, then go back to minimum, back to maximum... and so on

 

[techo]

thanks, that's what I thought
but I wasn't sure

 

[laroche73]

variable caps

The ones you refer to are usually made with two half-circle plates, so Exo's right. The older mica "compression" types used a screw to squeeze two or more plates together. There were also the "barrel" style caps, which used the screw as one of the capacitor plates, I think. In those and the compression types, turning the screw in just increased capacitance from min to max.