GIY (Grind It Yourself) precision film capacitor

This morning I was about finishing my active crossover, thought the needed 8 pcs. of 68 nF 1% film caps were in the parts bin. I only found 7. Dang! Fumbling with lots of caps in parallel and series to achieve 68 nF, no hit. Bleeding hell!

Necessity begets ingenuity: Picked a 100 nF Wima MKS4 and a piece of sandpaper and grinded the cap from the top. It took some strokes to get through the plastic coat. And then measuring it with the c-meter, getting around 99 nF, grinding, measuring 93 nf, grinding ... I ended with 67,87 nF.

The reason why that works is obvious:


And now back to soldering!




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