Quote:
Originally Posted by Electronic M
This isn't a favorite practice among restorers but is a solution Dumont used in its RA-103 to get a voltage not offered. When you put 2 electrolytic caps of the same value in series the effective working voltage is the sum of the caps, and the effective capacitance is half of an individual caps value (it gets much more complex if the caps are different values).
What I would do is put two 22uF caps rated in the 350V-450V range in series. Electrolytic caps have polarity like batteries (and will explode and or smoke if connected backwards), and when placed in series you want to connect the positive of one cap to the negative of the other. Additionally since electrolytics are rarely perfectly identical even from the same maker there's a tendency for the voltage to split unevenly...To prevent this get two 470K ohm 1W resistors and place a resistor in parallel with each cap. The loading of the resistors will be negligible on the circuit but enough to equalize voltage across each cap....This is basically the exact circuit used for the first lytic off the rectifier in the Dumont RA-103.
|
I'm back to working on my 103 again having cleared the bench of 4 restorations and I was tracing out that very circuit last night. I spent a lot of time looking for and installing a NOS relay for the often troublesome delay circuit for the rectifiers. This is a topic for another thread but the relay worked for the first time but I got smoke in the area of the vertical transformer. So I guess it's on to the next issue
