Capacitors

Capacitors come in many, many different shapes, sizes and voltages. They have two electrical connections. Some capacitors need to be wired in very carefully but all the capacitors used in the metal detector can be wired into the circuit in either direction. The capacitor used in this circuit should be available with the value marked clearly on the side. The component listing gives the markings that you should find on the capacitors to identify the correct ones.

Capacitor values are measured in 'Farads' but the unit is a very large quantity and most capacitors are only a very tiny fraction of a Farad. Fractions of a Farad are as follows: µf, nf, pf. Each of the oscillators has a 10pf capacitor which should have 10 written on it. There are also a number of 0.0047µf capacitors. Note that 0.0047µf is the same as 4.7nf, which is the same as 4700pf and is sometimes written on the component as 4702 (which means 47 and 2 lots of 0s = 4700)!