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Old 9th Oct 2018, 10:56 pm   #41
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
Default Re: Pilot Little Maestro Pilot Lamp Conversion

The problem with using X capacitors as voltage droppers is the self-healing and consequent loss of capacitance. Every switch-on surge (a cold valve heater, or a discharged capacitor, is almost a dead short circuit) tends to weaken the capacitor a bit until eventually there is insufficient power available and the circuit begins to misbehave, requiring replacement of the capacitor.

The company I used to work for did some tests and found it was better just to use a standard 400 or 630V capacitor, with a fusible resistor to limit the switch-on surge.
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