I built the circuit shown in the link with 240v


It did not work (produceing no spark), as I believe my capacitor was much too low of a value (around 5nf). Anyway, The capacitor was made from tin-foil like the one below


I then made another capacitor in the same way, though forgot to include the space at the end between the tinfoil. Because of this, the capacitor short circuited. This caused the light dimmer to go up in a puff of smoke. I know it was stupid and i'm done with that circuit now, but nonetheless I am still wondering why I got no spark. Even as the circuit had virtually no capacitance, the ignition coil produced no spark. This makes me think maybe the fault in the original circuit was not the capacitor? Also, does anyone know why this caused the light dimmer to die?

  • \$\begingroup\$ I saw this Instructable when it first came out about a month ago and my reaction was Nooooooo!! It's stupidly dangerous, so I'm glad you had the sense to abandon it. The writer claims you shouldn't use motor oil for insulation because it it inflammable and then goes on to recommend cooking oil! Has he never seen a chip pan fire? As far as I can see the capacitor is only in the mains circuit, not the really high voltage side so it doesn't have to be a high voltage one, just mains rated, say 400V. The dimmer failed because it was effectively across the mains with no current limiting. \$\endgroup\$ – Peter Jennings Nov 1 '19 at 11:35

Congratulations on the capacitor experimenting - it's good to see people trying such things. Ensuring they are not short circuited is a very good idea - but you know that :-( :-)

You have asked this question repeatedly in slightly different forms.
The answer is always the same - the capacitor was far far far far too small - about 200 times smaller than recommended.

You MAY have been getting some output but not have been able to draw a spark due to the low output.

The dimmer may not have functioned at such a low current.

Using a capacitor from a dead microwave oven would be better.


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