Hello, a query about power supplies

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Hi all,

Firstly, let me say hi to everyone on the forum! This place looks really good, I'll enjoy reading the posts. :)

I've started to get an interest in tubes. I'm quite knowledgeable with electronics in general, but I have never done anything with tubes, but I'd like to change that!

I thought a good place to start would be to make a power supply from tubes, however, I have no idea where to start! Would you guys mind helping me?

I have only two factors (at the moment!) I would like:

Runs from UK 240V mains

Variable voltage


I don't know what sort of output voltages would be useful, so hopefully you guys can help me out with that!

I have done a search, however I cannot seem to find anything which is very clear. Although a few variable supplies have come up, they have all been for American supplies, and I'm quite 'anal' when it comes to constructing projects! Everything must be checked and checked again, and I must have the correct transformer, etc. Sorry. :eek:

Anyhow, I look forward to your replies!

Many thanks,

Sparky
 
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Guys, please remember that Variacs don't provide any mains isolation.

For a PSU built for general experimenting with, its vital that it uses an isolation transformer somewhere in the chain. I'm sure you all know that but better safe than sorry.

:)
 
Thanks for the replies!

I would prefer to keep it isolated with transformers - much safer that way. :)

I know it might not be the most useful of things, but I don't mind that - half of my projects are just to learn about something or just because I can. :) No harm in that. :)

What I'm mostly confused about is where the pot. is to be placed.

Perhaps a simple schematic might help? :)

Sparky
 
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Joined 2007
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Sorry, I presume one would control a grid voltage or something with a potentiometer.

I will look into producing a fixed power supply. Many thanks.

Yes you would use a pot for that. To make a variable PSU that can supply a bit of current (which the pot can't) can be done easily. All you need is the basic unregulated supply (say 300 volt) and to add a high voltage high power series pass transistor (actually two to make a darlington) and feed the base from a pot. One resistor and one more transistor will add current limiting and protection.
 
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