help with rail voltages

[Svetlana]

I am able to get some 2nd hand transformers that would give me 36vac--0--36vac.....maybe around +/- 46vdc??

Is that going to be to high when using irfp044s in an aleph x??

[Nelson Pass]

Without a load this will come out about +/- 50V. With a load
it will be less, but how much depends on the hardware.

This is high, even for an Aleph X. How big are they (VA rating)
and do they have 240 V primaries? for that matter, what is
your voltage?

[Svetlana]

Mains Voltage here is ~240VAC.

There are several avaible, D55-449M Fuji Electric Co Ltd, 3.55KVA for $120 each.

The primary is 240vac with several tappings.

The lowest possable sec voltage is a taped 36vac, I was thinking of using two transformers, one for each rail.

I am guessing the highest possable sec voltage is probably no more than 40vac, possably still too low to give me much power.

They only weigh 19kg, is that a bad thing?

[uli]

Go ahead with those monsters


Only thing to be aware of:

Buy enough aluminium


Uli

[Duck-Twacy]

Large second hand 3550 VA trafo that only weigh 19 kg

HHUMMMMMMMMM (50 hz)...

[uli]

I think, they will be ok since they won´t be loaded that much

Uli

[Svetlana]

Supposing the hum wasnt too bad, the irfp044 being a 60volt device, and the rails being +/- ~48V ......am I going to cook my 044's?

[Panelhead]

Originally posted by Svetlana
Supposing the hum wasnt too bad, the irfp044 being a 60volt device, and the rails being +/- ~48V ......am I going to cook my 044's?

I think yes, the 044's will not last very long. Also some are only rated at 55 volts.
Since these transformers are 120.00 each, why not contact a winder about getting a pair that give you 25 volt outputs. 240.00 should buy what you need, just not in a 3.5kVA unit.

George

[Svetlana]

So whats the highest safest voltage I can run these parts..maybe 1/3 of their stated voltage ratings? maybe a half? why cant I run them at their full 60 volts?

[Luke]

Hi Svetlana,

you could parallel two 40 volt windings and use them as plus minus 20 volt rails and just ground the centre where they meet.
I think you need resistors in series to ground though to keep the rails the same?
With 6 amps bias that should give abut 120watts class A and dissipate close to 300 watts per channel
BTW are there any more of these, im slowly getting bits together for my aleph-X. A company name or phone number of who is selling these would be nice

cheers arthur