Series of Diode on HT Plate

[Elektor78]

Hi to All

I have many times seen the Anodic Rectifiers Build with series of two diodes.
as this : http://www.drtube.com/schematics/laney/lc50.gif

If I use series of two 1N4007 (1000V 1A) for rectifier 1500Vac (without any resistive divider) in reverse bias, Have I 750Vac on each diode ?

I suspect that this connection doesn't guarantee the equal distribution of the potential during the reverse polarization of negative half-wave.
but this schematics run on many amplifiers... I am wrong ?

ThankYou

(sorry for my english from Italy)

[Miles Prower]

Originally posted by Elektor78
I suspect that this connection doesn't guarantee the equal distribution of the potential during the reverse polarization of negative half-wave.
but this schematics run on many amplifiers... I am wrong ?

No you are not wrong. That isn't the right way to use silicon diodes in series. These require both equalizing resistors and capacitors for transients. Otherwise, the voltage distrubution won't be even, and may even cause poofage.

It's either a design that cut corners due to stingy pencil-pushers, or they didn't know what they were doing.

[DigitalJunkie]

I have seen large value resistors in parallel with the diodes before,similar to the equalizing resistors used on series'd capacitors.

Here's one example:
http://www.dogstar.dantimax.dk/tubes...cs/pwrsups.gif