Re: "Forming capacitors" - means what?


KB6NAX
 

Yes, using a current source is the best way to go. You set its
compliance to the rated voltage of the capacitor and its current to a
value that will not produce excessive dissipation in the cap at full
voltage. Problem is, most reforming goes on with caps still in the
equipment and any one of several or more caps can be leakers that
need reforming time. The nice thing about power supplies with vacuum
tube rectifiers is that when the rectifier's heater is running at
substantially lower voltage the cathode is emission limited and the
plate resistance is high, providing you with a nice current limiting
resistor. Still, a variac is the simplest way to effectively control
the reforming process. Never run the voltage up to fast if you don't
want to ruin a potentially good cap and make yourself more work.

Arden

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