Looking for some power intelligence.

[snax]

I am looking for a transformer for my next project and i'm having trouble as to how this secondary works:

Secondary SEC I 0 - 275V - 330V / 0,4A

There are other secondary wndings on the transformer but I do not understand this format. Its not a centre tap but is it a tap between 0-330V?

What would you use it for?

Any help appreciated.

 

[scottjoplin]

A valve amplifier, is that what you are building?

 

[snax]

could be.... at 330v it would be the mother of all transistor amps however at 0.4amps, would not be able to pull skin off a custard!

 

[DF96]

A secondary tap does not have to be at the centre of a winding. You could use it, with the right circuit, to produce two DC voltages - although one of them would only be half-wave rectified so best used for a low current auxiliary supply.

 

[snax]

But would that not produce unbalanced voltages in the secondary winding due to unsymmetrical currents flowing in the common third connection because of unbalanced loads?

 

[kward]

Another option for that secondary is to use it as either a 275v winding or a 330v winding at up to 400 mA.

 

[DF96]

Put a bridge (+capacitor) on one set of terminals. Put a single diode (+capacitor) on the other one. Choose correctly and you have a ful-wave rectified main DC supply and a half-wave rectified auxiliary DC supply (which could even be negative, if you want).

Alternatively, just use the voltage you want and ignore the other one.

 

[snax]

Cheers guy's, It was a new one on me and DF96 you have opened a wealth of new opportunities that I will explore.

Dan

 

[PRR]

But would that not produce unbalanced voltages in the secondary winding due to unsymmetrical currents flowing in the common third connection because of unbalanced loads?

It can be 275 -or- 330V.

It wants a full-wave bridge, as said.

If you just use the 275V winding, you "waste" about 10% of the copper+iron you paid for. This "waste" is small compared to the benefit of getting closer to your intended DC voltage, which is always partial guess-work due to bad sag in capacitor-input filters and incomplete specification of all parasitics.

Expect either 380VDC or 460VDC. Or less if your load is close to 400mA AC (with cap-input, about 250mA DC).

This PT can power around 50W-60W of tube-amp. 6L6 or EL34 at 4K load, for example.

 

[snax]

Cheers PRR