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Connect two transformer in parallel? Answered

Hi... I want to know that can we connect two center tap transformers in parallel? both are same rating of 24-0-24v, 5a. I want dual supply (plus, minus 24V) for audio amplifier that I am planning to build.
Can someone explain me all the risks, cautions, etc.?
(I am new in audio amplification circuits)



Best Answer 4 years ago

The ac secondaries of many control transformers are designed to be connected in parallel
for increased current output or in series for increased voltage output.

When you connect windings ( of identical secondaries ) in parallel
That  means the AC voltage sine wave goes high on both coils at the same time !

If you phase them in opposition they will form a very Bad double high current short circuit !!

A good way to phase them if you don't have a scope is to place an incandescent light bulb
between the final connection of two coils being paralleled.
It, the light, should not even glow.


What if i connect them in parallel after rectifying (full wave) both secondary winding individually? I think that's a easy and safe way right?

Yes ...  that  works quite well... You will double up on rectifiers.
In fact if one DC is a bit lower it will come in to use when the
other drops down due to loading..
I call that inherent load sharing.

bro i have a question, i have two transformers 18 0 18 2amp and 18 0 18 1.4 amp, i bought the 2amp today becoz my previous one was creating problm, after using the 2amp iam still hearing some noise, if i connect both of them together in a formation where both of them are in the box on one another, would it create a problm, my previous transformer was creating the noise distortion so i bought a new transformer, plzzzz tell me its urgent

Is this ckt right? what rectifiers should i use? where to add filter capacitors?


Yes.  see added components
The bridge is here use any 100v 8A bridge as a minimum.
There are ceramic or film capacitors used to filter the fast voltage transients
that the polarized capacitor are too slow to filter but can affect the audio amp.


BTW 24VAC is the RMS value of the sine wave
after full rectification the peak of the sine is 1.414 times 24 equals 34VDC
See image note the dashed droop from peak to peak
a ripple of 100Hz if you live at 50 cps or 120Hz if 60 cps.
the next step is to add a dual regulators.