Using existing transformer winding to provide and additional supply

[BL21DE3]

Hi,

I'm looking to implement the following VU meter circuit in my EL84 valve amplifier build, http://www.jlmaudio.com/VU%20Buffer.htm, which can be run from 9-30V DC.
However I want to avoid adding an additional transformer into the build if I can. I've attached the schematic for the PSU section of the amplifier and was wondering if anyone here could recommend a way to derive the necessary voltage from the supplies already present?

I had though about switching the heater supplies to be solely DC and then using a voltage multiplier to create the voltage required but I'm not certain if that would be a sensible option?

Any advice or suggestions would be appreciated.

Regards,
Ewan

[analog_sa]

Originally posted by BL21DE3

I had though about switching the heater supplies to be solely DC and then using a voltage multiplier to create the voltage required but I'm not certain if that would be a sensible option?

Nothing wrong with this that i can see. And you don't have to convert the heaters to dc.

[BL21DE3]

analog_sa

Thanks for the reply. Having looked a little into voltage multipliers there are quite a few topologies to choose from, do you have any recommendtaions for my situation/requirements?

Cheers,
Ewan

[BL21DE3]

Just wondered if any of the more technically minded members of the forum could cast a critical eye over the following quadrupler circuit I was thinking of implementing to resolve my issue of deriving a 9-30v supply for my VU driver circuit.

I've run a simulation of the circuit in LTSpice and using 100µF/50V caps and 1N5819 diodes I could get ~12V output from my AC heater windings (see the schematics/links in my first post) which is all good. However my questions/concerns are as follows:

1) Will implementing this circuit affect the AC heater windings in any way i.e by using the CT of the AC heaters as the ground for this circuit?

2) Would the ground for the VU driver circuit also be attached to the CT of the AC heater winding, and if so would this affect the heater supply?

Any advice/comments would be welcome.

Regards,
Ewan