Make: Volume 87

variable capacitor,” one of the first hits is likely

to be the component we suggest, part number

223P (Figure

C

). It actually contains two variable

capacitors on the same shaft, with maximum

values of 140pF and 60pF (picofarads). You need

to connect them in parallel, for a total of 200pF.

You can use alligator jumper wires for this, but a

terminal block with screws spaced at ⁄" (8mm)

is better (Figure

D

). The center terminal should

go to negative ground on your breadboard.

Wherever you buy your variable capacitor,

also buy a plastic tuning wheel (Figure

E

) which

screws onto the shaft, to prevent the touch of

fingers from affecting the capacit ...