Model 18 (124) Electrolytic Voltage - Printable Version
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Model 18 (124) Electrolytic Voltage - Pappy B - 07-20-2013
I have been rebuilding a model 18 (code124) and I restuffed the old E-Cap cans. I recently discovered that the 10uF connected between chassis and B- (part of #59 on the schematic) is 50 volts. I used a 500 volt cap. The radio plays good but I am wondering if I need to change it back to somewhere between 50 and 100 volts.
RE: Model 18 (124) Electrolytic Voltage - jerryhawthorne - 07-20-2013
Should work just fine Pappy. Welcome to the Phorum.
Jerry
RE: Model 18 (124) Electrolytic Voltage - Jim Dutridge - 07-20-2013
One thing for sure, you won't have to worry about the surge at turnon.
RE: Model 18 (124) Electrolytic Voltage - Pappy B - 07-21-2013
Thanks for the reply's, I just wonder if it will get enough voltage through it to keep it healthy over time.
RE: Model 18 (124) Electrolytic Voltage - raydog - 07-21-2013
Doesn't matter. It's the max voltage you need to consider. You are just oversized or overrated on the cap... no harm done, should last a long time
Don
RE: Model 18 (124) Electrolytic Voltage - morzh - 07-22-2013
Well, let's be correct: for tube radios this in practice does not matter, you only have to deal with a larger size cap where you could use a smaller one.
Outside the tube radio applications yes, you do not want a higher voltage cap in place of a low voltage one. At least most of the times.
RE: Model 18 (124) Electrolytic Voltage - klondike98 - 07-22-2013
morzh Wrote:Outside the tube radio applications yes, you do not want a higher voltage cap in place of a low voltage one.
Why? Just curious and interested...thx.
RE: Model 18 (124) Electrolytic Voltage - BrendaAnnD - 07-23-2013
I think it has something to do with ESR?
RE: Model 18 (124) Electrolytic Voltage - morzh - 07-23-2013
Yes, more or less. That is ESR/ripple vs size vs capacitance vs voltage.
Well, eventually comes down to size.
Same size will have lower capacitance vs higher voltage dependency, and the ripple rating either stays the same or goes down if you keep the same case size but increase the voltage. Most times, especially if the increase in voltage is several times, it will go down.
So you have to increase the size quite a bit since you want the same capacitance and not lose your ripple rating. In old radios we are not limited with the space.
In any other applications we are.
Also in commercial consumer application the significant difference in price between even 16V and 50V caps of the same capacitance and ripple rating will simply kill you.
RE: Model 18 (124) Electrolytic Voltage - klondike98 - 07-23-2013
Thanks for the explanation morzh and Brenda. ESR in my field is electron spin resonance
