VOLTAGE DOUBLER FOR POWER SUPPLY

[ampfab]

I have a power transformer out of an old Wurlitzer organ that powered 4 7591 power tubes and about a million 12ax7s.
the original power supply used a voltage doubler.
would this doubler circuit work well, also provide a "half power" supply?
I'd like to use it to power a pair of 6550s.

[martin manning]

I don't see why not, but I would add some balancing resistors across the stacked caps for the half-power mode.

[Kagliostro]

To me no, resistors are not to be used

the resistors are to be used if you have the cap in series as when the switch is open, but if the switch is closed ???

But why to have 1 x B+ and 2 x B+ alternatively ?

also if you can do that, what will be at the plate of the preamp tubes, do you want to run also those at 1/2 voltage ?

K

[martin manning]

To me no, resistors are not to be used the resistors are to be used if you have the cap in series as when the switch is open, but if the switch is closed ???

I don't see any problem with the resistors being there when the switch is closed. The caps will still share voltage equally.

[Kagliostro]

Rethinking about that with the switch closed the resistors will act as bleed resistors, so may be there is no contraindications

K

[Danny_J_Glover]

ALWAYS INSTALL BLEEDER RESISTORS ON HIGH VOLTAGE CAPS.

[Kagliostro]

I would like to know

But why to have 1 x B+ and 2 x B+ alternatively ?

K

[martin manning]

Halving the B+ will cut the power in the same way as whole-amp "power scaling," which some people like.

[starlite2991]

I concur. About a 150k 1 watt would be needed for the bleeder resistor. Not having one is like playing with fire

ALWAYS INSTALL BLEEDER RESISTORS ON HIGH VOLTAGE CAPS.

[Kagliostro]

Halving the B+ will cut the power in the same way as whole-amp "power scaling," which some people like

May be, but the most part of people didn't like it and prefer to lower the voltage only to power tubes and PI

So my council will be to have from the same PT a branch with constant voltage to be used to supply the preamp tubes

one other bridge, some cap and resistors and it is done

K

[Firestorm]

I take it this transformer doesn't have a center tap.

[Kagliostro]

Whith branch I didn't mean the branch of a winding with CT

I mean

a branch with standard bridge rectifier

and

a branch with doubler (with the additional switch)

bot branch connected to the same winding

K

[ampfab]

This transformer does not have a center tap.
I plan on mocking-up this power supply and power amp.
What rectifier part number would you guys suggest?? hoping to have a B+ of 425-500v. maybe build the bridge rectifier from 1n4007s.
i'll let you know how it goes.
thanks for all the thoughts.