staked or parallel PSU ?

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mik

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Good mornig  gentelmen.

I have to build a special PSU with 12 and 24 VDC.
starting with 12V AC for your experience, witch one is best , staked one or capacitor coupled voltage doubler one ?
CFimjjZ.png

P3A85Fx.png
 
mik said:
Good mornig  gentelmen.

I have to build a special PSU with 12 and 24 VDC.
starting with 12V AC for your experience, witch one is best , staked one or capacitor coupled voltage doubler one ?
CFimjjZ.png

P3A85Fx.png
I am not familiar with "staked" terminology?

The doubler schematic does not look to me like it would work... the transformer windings will never swing negative to charge the doubler caps.  Perhaps the ground of the top charging string needs to be connected to 12v while I don't promise that will work either.

Have you tried bread boarding this to see what happens?

JR
 
> PSU with 12 and 24 VDC.

At what current/power ? ? ?

Any power supply thinking must include how much work it has to do.

Here there is a specific reason. Which rail has how much current?

If you need 24V at 1A and 12V at 0.1A, then I would just build a 24V 1.1A supply and add a little 12V regulator.

On the other hand if you need 24V at 0.1A and 12V at 2A then it does not make sense to make a lot of 24V and waste nearly half of that for your big 12V load.

What are D3 D4 doing for you?

Is R6 R7 needed?

> Have you tried bread boarding

+1
 
thank you gentelmen !

@ PRR :  D3, and D4, are fast recovery diodes, like UFxx,  are there to sincronize the bridge and reducing the frequencies of ringing,  according to Merlin Blencowe "design Power Supplies for Tube Amplifier" pag 29.
anyway ,  the current on 24V rail it's about 100mA and on 12V it's about 1A

@ JR : i forgot to design central tap transormer in the doubler one schematic, for the rest it's a normal textbook  PSU I've already build few of this and they work ok.

M.
 
mik said:
I have to build a special PSU with 12 and 24 VDC.
1st one won't probably work because primaries in series work well ONLY if load is identical; in practice, primaries share voltage according to inverse of current drawn. Why not connect them in parallels?
2nd one won't work either. Negative of C1 should be referenced to positive of C2.
What's the use of D3/4, R6/7?
 
abbey road d enfer said:
1st one won't probably work because primaries in series work well ONLY if load is identical; in practice, primaries share voltage according to inverse of current drawn. Why not connect them in parallels?
2nd one won't work either. Negative of C1 should be referenced to positive of C2.
What's the use of D3/4, R6/7?

hello Abbey Road d enfer, thank you.
If I understud your claim  right,  if you tie C1 on  C2 you'll stak Voltage rail,  so the 24V become 24+12VDC refered to ground.
About  R6/7,  in case of short I can indentificate witch rail is compromised soon. 
About D3/4 read above.

M.
 
mik said:
hello Abbey Road d enfer, thank you.
If I understud your claim  right,  if you tie C1 on  C2 you'll stak Voltage rail,  so the 24V become 24+12VDC refered to ground.
Indeed, you must reconfigure the grounding of the 24V regulator for correct output. Notice that I mentioned stacking only the bridge rectifier and the capacitor, not the rightmost part of teh circuit.
 
abbey road d enfer said:
Indeed, you must reconfigure the grounding of the 24V regulator for correct output. Notice that I mentioned stacking only the bridge rectifier and the capacitor, not the rightmost part of teh circuit.

oh!  I see, I'll post soon a corrected version of what you suggest.
M.
 
ok, here it is. Now first part of the circuit is staked, and regulator is refered to ground, is it right ?
Sure  C8/5 need to have the same rating of C1, D3/4 are optional.  it make sense to me even if
in this manner the 2 rails are not indipendend each other, if 12V will Sags because the load, 24V will sags too,
anyway this seem to me a middle way between N1 and N2 schematics, the best of both.
thank you.

M.



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