Using multiple power transformers in a PSU

When building a PSU with multiple outputs, say +24V 0V -24V and
+18V 0V -18V. Is it possible to use multiple power transformers instead of using one with multiple secondaries? I've never seen this in a PSU before but it seems cheaper than ordering a custom wound one.

Will there be a ground problem when connecting the 0V from both separate transformers together?

No problem. When volumes are very low it makes perfect sense.

Note that you have the opportunity to get some magnetic field radiation cancellation by the relative position of the two (or more) transformers. It can help a lot and in some cases make E-I core transformers work almost as well as toroids.

That is not a problem. I have a project on the go at the moment that will be using 4 mains transformers some of which have 4 secondaries. In a lot of old military valve gear they had separate HT & filament transformers.

Ok, thanks all :thumb:

Was looking at the sowter site and saw these prices for custom wound power trannies :shock:

[quote author="radiance"]Ok, thanks all :thumb:

Was looking at the sowter site and saw these prices for custom wound power trannies :shock:[/quote]

My quasi-partner has been getting quotes on a custom power transformer in 100 quantity. Edcor has been about the only one with less-than-breathtaking prices.

I have projects with multiple salvaged transformers, no problem.

When you common the Ground, just make sure that all your transformers have a CT. If you've just got a single secondary, you can get into trouble!!


Justin

Another potential issue:
Dunno about the sizes of the TXs, but if they're big then try to keep all the weight away from the rear of the unit - or provide mechanical support.

I learned the hard way, a pair of SWR-amps (alu enclosures) with power-TX at the rear, a fast bumpy ride back from a gig and the damage was done

[quote author="thermionic"]I have projects with multiple salvaged transformers, no problem.

When you common the Ground, just make sure that all your transformers have a CT. If you've just got a single secondary, you can get into trouble!!


Justin[/quote]

Well, I might have one with a single secondary. That's a 24V one only for powering relays and lamps inside pushbuttons and behind meters. I'll just keep that one floating I guess. That will not cause problems right?

Another option is to use a transformer with +12V 0v -12V secondaries and use the -12V and +12V to get my 24V. That way I'll have a center tap with 0V. Somehow I don't see any benefit in this :?

As long as your single secondary transformer used to power the LEDs etc is left totally floating and doesn't get connected to your master Ground, you'll be ok.


Justin

Ok, floating it is then... :grin:

Thanks!