Induction coil

[peter scott]

Well I reduced the input voltage to 3v. and with my scope across the contacts I got about 400 volts p-p but placing my 0.1, 0.2 or 0.3 uF across it made very little different to the amplitude or ring frequency so I opened the box and discovered why.

   

Its voltage rating is a little short of the mark but it measures 0.993uF and isn't leaky. Wikipedia suggests the capacitor value is in the range 0.5 to 15 uF.

Peter