Would it work to use multiple transformers in series?

[Spasticteapot]

ApexJr sells 24V @ 7A transformers for a whopping 8$ each. A 300VA transformer with 2 25v windings is 40$ or so at Parts Express.
Would it work okay to use two of the aforementioned transformers in series to provide center-tapped 48VAC? Would this work better with dual diode bridges? Or should I bite the bullet and stop being such a @$#@$ cheapass? It would seem to me that this could easily result in some funky problems with balancing the output power..but both are center tapped. Should I use half of one in series with half of the other, or rectify them and then put them in series?

Thanks,
Joe.

 

[mrlots2do]

Hi Joe,
If I understand you correctly, the Apexjr xfr is +12 0 -12 (24vct). You want to use two in series for +24 0 -24. It can be done but if your using BrianGT's rectifier boards wouldn't it work as well having the two xfr's parallel and taping center taps.

Oh, be sure output voltage is same.

Just my 2 cents.

 

[lndm]

Connect the primaries in parallel so both see the full mains. You can treat the secondaries as independent. If you ignore the centre taps, you could connect one lead from each secondary (the lower from one and the upper from the other) together creating a new centre tap. More or less pretend they are dual secondaries from one such xfmr. Leave them separated if you wish.

 

[Spasticteapot]

So, you're saying the following would work okay?



+Transformer1- ----- Center Tap ------- +Transformer2-

Both would be connected in paralell to line voltage, of course.

Is this likely to cause an offset in in the input voltage? If not, why have I yet to see it used before?

 

[AndrewT]

Hi,
yes, connect the primaries in parallel to the mains supply.

Ignore the secondary centre taps. (although you could tap off 12Vac to power low level stages, relays, filters etc).

Use the 0-24Vac from each to create 0 - 24Vac + 0 - 24Vac to give your new supply rated at 336VA.

This will run upto 200W of ClassAB amplifier very well and adequately power upto 300W.

 

[Spasticteapot]

Thanks for your help!
I'm getting six of these; I'm building these with two of my friends. The total cost per amplifer (they're modified "Chill-Amps", under Fedde's design but with a CarlosFM snubberized PSU) is under 50$ with these! I'm a high-school student, so my budget is really, really small; your help will likely mean that I can also afford to make some speakers to go with the amps!