Using the anotated schematic I attach. I have this PSU with bridge B3 populated. If I feed AC into AC1' and AC2, no CT connected, and take a single rail positive supply out using v+ as pos and V- as zero.....is this acceptable? Have tried it on the bench and it 'works' but I'm not certain it is the done thing. To my mind the caps aren't doing anything as they have no reference.
make sure you have bleeder resistors installed parallel to the main filter caps to create a virtual ground...
It is done that way all the time. using the two outer taps and ignoring the center tap, that goes into the bridge as AC and comes out as DC where the plus is the positive voltage and minus is now ground. Or using one outer tap and the center tap into the diode bridge. Remember to isolate the unused tap so it doesn’t come into contact with anything. The unused tap is not ground!
fwiw, the center tap is just a reference point for the zero volts in case you want to split the supply into plus or minus rails...no current is supposed to flow unless the center tap is not exactly at the midpoint of the secondary winding...
??????
In a split supply amplifier, all of the speaker current flows into/from/through the centertap/ground node
What you say applies to no signal, DC only.
Otherwise galvanic/"copper" centertap would not be needed, only a couple of resistors .... we all would love that but sadly it´s not the case .
In a split supply amplifier, all of the speaker current flows into/from/through the centertap/ground node
What you say applies to no signal, DC only.
Otherwise galvanic/"copper" centertap would not be needed, only a couple of resistors .... we all would love that but sadly it´s not the case .
Thanks for the comments. Good point on the bleeders as currently they aren't populated. Once in situ does the single rail arrangement 'see' all 4 smoothing caps or just the 2 on the positive side?
If you ignore the center tap, and let it float, the caps are in series between + and - and work normally. They don't 'know' that you decided to ignore the center tap.
For decoupling ripple between + and - the cap value is of course half the individual cap value, as they are in series.
Just consider it a black box with two output pins, one pin is positive to the other. Just use it as you would use a battery with a + and - pin.
What do you want to use this for?
Jan
For decoupling ripple between + and - the cap value is of course half the individual cap value, as they are in series.
Just consider it a black box with two output pins, one pin is positive to the other. Just use it as you would use a battery with a + and - pin.
What do you want to use this for?
Jan
I built it up as a CT/ dual rail for an FH9VX but I'm currently playing with ACA and also Abraxalito monoamps, both of which are 24v single rail and so rather than make another PSU I thought of using this as a single rail .
The comment on half the capacitance is interesting. Understood. It has 88kuf in there so 44k available is still enough I think
The comment on half the capacitance is interesting. Understood. It has 88kuf in there so 44k available is still enough I think
I assume you will use another transformer to get 24V , not the one you used for the fh9vx amp,
anyway, as the others said using that dual rail psu as a single rail psu will work , but it's a waste of capacitance and space too.
anyway, as the others said using that dual rail psu as a single rail psu will work , but it's a waste of capacitance and space too.
Oh yes sorry initially I had a 35-0-35 for the +/-50. For this application an 18vac which actually gives me about 28raw DC.
Understood about not ideal but it is here and built and saves me making another, for now/testing atleast.
Understood about not ideal but it is here and built and saves me making another, for now/testing atleast.
the Nelson Pass dual bridge arrangement is superior to center tapped...
https://encrypted-tbn0.gstatic.com/...UEfaHYzoL47uC6M-yOW8AJzV68Csx06S9XR4&usqp=CAU
https://encrypted-tbn0.gstatic.com/...UEfaHYzoL47uC6M-yOW8AJzV68Csx06S9XR4&usqp=CAU
