Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: slash1986 on February 05, 2024, 11:11:25 am

Title: Anode voltage power supply.
Post by: slash1986 on February 05, 2024, 11:11:25 am

Hi, I would like to ask you. I'm having trouble finding transformers here in my country to build a power supply for my tube projects. On various Chinese sites, you can see small switchig step up power supplies for a few euros. Is it possible to build a power supply for the anode current with these boards?

here is an example: https://it.aliexpress.com/item/4001247455370.html


{edit: tracking URL removed - PRR}

Title: Re: Anode voltage power supply.
Post by: tubeswell on February 07, 2024, 02:05:06 pm

All depends on the HT current you need. 70V.A/450V = 155mA tops.


However, I personally wouldn’t use one of those power supplies - is it really going to last at 70W dissipation? I highly doubt it. Get a proper PT.

Title: Re: Anode voltage power supply.
Post by: HotBluePlates on February 07, 2024, 05:57:52 pm

It's often cheaper to save your money, wait & buy the right part.

It's often more expensive to buy the "cheap part," find out it doesn't work as well as hoped, and then buying "the right part."

Title: Re: Anode voltage power supply.
Post by: slash1986 on February 11, 2024, 11:59:08 am

Since I have 2 120VA transformers with 230v primary and 15-0-15 secondary, I would like to use them and connect the two secondaries  to have 230v on the primary of the second transformer. I could then rectify the voltage with a voltage doubler circuit like this:

Title: Re: Anode voltage power supply.
Post by: PRR on February 11, 2024, 12:35:40 pm

Two times 230V AC in a capacitor makes about 650V of DC. Do you need that much?

(It's what my 300 Watt Bogens ate.)

Title: Re: Anode voltage power supply.
Post by: slash1986 on February 11, 2024, 01:29:29 pm

probably not. but I would like to have at least 400v.
with a normal diode bridge I would only have 325 v. some advice?

Title: Re: Anode voltage power supply.
Post by: WimWalther on February 11, 2024, 09:18:09 pm

Do you own a Variac (aka variable auto-transformer)? You could arrange your PTs as you suggest, with the fullwave doubler and use the Variac to adjust the output.

If you are planning to work with electronics as a hobby, you really should have a Variac in the first place. They are extremely useful for testing new equipment or equipment under repair.