Summing transformers

ben62670 · September 2009

Well I have a bunch of 2 amp 28.7v center tapped transformers. I need to sum the amperage of them. Can this be done with satisfactory results? Would I rectify the ac, and sum them all? Also what if I ran the secondaries as primaries?
Would this be a way to boost the voltage to run some tube projects? If my math is correct I could get a B+ of 240vdc if I bypass the center tap?
Thanks
Ben

ShinAce · September 2009

ben62670 wrote: »

Would I rectify the ac, and sum them all?

Without thinking it through, I'm saying yes.

Do not run the secondaries as primaries, they will likely burn out.

ben62670 · September 2009

I think all the wires are rated a 600v. I know nothing real bad would happen summing DC, but I have never done it, and noise is the only thing I am concerned about.
Thanks
Ben

CoolJazz · September 2009

As DC, you simply sum them via a diode on the output of each supply before the summing junction. This is what is done with "redundant" power supplies.

In that case, it's not done to take advantage of the current, just to keep DC available if any supply dies. The diode isolates each supply from the others. Make sure the diode can more than handle the current you're supplying.

CoolJazz

disneyjoe7 · September 2009

Being you have a 4.28 to 1 ratio transformer, I think if you power the secondary you should have 514vac output. :eek:

Your center tapped transformer for 28vac you could use the outside wires and not use use the center wire. You then have a 28vac transformer, using the center wire so you diode the output wires together with the center being the return wire. You have 14vac transformer with double amp out.

ben62670 · September 2009

I like the sound of 514v. I could tube rectify and tube regulate. I was surprised with the SQ of a tube pre with that setup.

disneyjoe7 · September 2009

Hmmm.....

I don't like the fact you may power up the secondary coil, you may need to try that first. Check for smoke. 514vac should be around 600vdc when you diode up and put a cap on it.

Your nuts, but I think you know that already.

BTW I may be able to get an used high voltage transformer, I could pick one up and you could pay me later when I go up there to see those speakers. I just need to know what the transformer watts you need and the voltage in and out you need. And the most $ you what to pay for it.

ben62670 · September 2009

Yeah I ain't scared. The doctors are still trying to figure out if I'm nuts or stupid.
I was going to try one outside with an extension cord, a light fuse, and on the driveway. If it sizzles oh well. If not I'll put a load on it, and see what happens. I am just looking for something to play with. I can't sink any money into a transformer yet, but I can work on the design if I know what I have to play with. Thanks much for the offer, but I have to pass for now. See ya soon:)
Take care.
Ben

disneyjoe7 · September 2009

I could still check to see what's available, it's old military stock sometimes things are really cheap. I'm thinking $20 - $30 bucks with "Free delivery" you pay what the receipt is.

ben62670 · September 2009

Can't beat that. I'll give you a call soon(in a few days) when I figure out what I need. I have your number plugged in, but I don't remember the best time to call.
Thanks Steve.
Ben

disneyjoe7 · September 2009

Ben, anytime during the day is cool to call.

Summing transformers

Comments