Dumb Dumbleator Question.

[Charlie Wilson]

Hello, I am building a couple of Dumbleators and I notice that everybody seems to use a .22/200v cap for the LNFB. Why should that cap not be a 400v cap?
CW

[martin manning]

It should be a 400VDC rated part to cover operation with no tube installed, power-up with standby on, or no standby as I did. Most film caps will withstand a significant over voltage for a short time, and once the recover stage is up and running it's anode voltage is down to 220V or so, but it's not the best idea to rely on that. This is the part to use: http://www.mouser.com/ProductDetail/Cor ... EYEg%3d%3d

[Charlie Wilson]

Thanks Martin. I think years ago Brandin suggested using a .22/200v cap and ever since everybody has been doing it that way but I agree a 400v cap seems like a better idea.
CW

[Mark]

Folklore at work again, it would seem.