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Old 27th November 2004, 11:05 PM   #11
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Quote:
Originally posted by Sch3mat1c
Gregggggg, you got the FWB 90 degrees sideways. Look again.

Tim
I do?

Quote:
Originally posted by fdegrove
Hi,



If you mean a setup where you use two diodes and a half wave tube rectifier in a FWB configuration then I don't think there is any such problem as you state.
Hmmmmm, I'll re-scope the setup I tried.....a 5Y3+2x1N4007. I had killer sawtooth troubles

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Old 27th November 2004, 11:16 PM   #12
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Default A few quick thoughts

Forgive me if his was already suggested. I just read the initial post containing the question.

You can use four diodes as a bridge on the outside (206V winding terminals). Then use an EZ-80 slow warm-up rectifier (if that is the tube you must use), with plates paralleled for more current capability to each separate amplifier circuit.

The additional use of tube rectifiers will not stop silicon diodes from producing switching noise however. Someone please correct me if I am mistaken. This noise will travel back into the power xfmer and come out the other windings unless you use a transformer with a shielded HV winding. The noise may be attenuated somewhat through the rectifier tubes.

Snubber caps of 0.01 mF value at 1 kV DC rating can be used across each diode to help supress the switching nois. A parallel LC resonant network filter in series with each transformer HV lead tuned to the resonant frequency created between the output winding of the transformer and the stray circuit capacitance (usually 40 KHz to several hundred KHz) can also help keep this garbage out of the transformer. A capacitor across the HV winding of the xfmer alone (try 0.01 uF/1kV) may be enough to do the trick.

You could use one or both of the motor run caps on the output of the SS bridge prior to feeding the anodes of the EZ-80's. A separate electrolytic of a value not exceeding about 47 uF could be used on the cathode outputs of each EZ-80 to act as reservoir filter for the amplifier attached to that rectifier tube.
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Old 28th November 2004, 03:30 AM   #13
jlsem is offline jlsem  United States
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Although an engineer I ...
Wow - already. Where did you get your degree so fast?
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Old 28th November 2004, 03:59 AM   #14
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Quote:
And you need two bridges ... why?
To minimise the interaction or cross-talk between the two channels by using two separate PSU, although both channels are sharing single transformer.

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What do you mean by weak? Insufficient for whatever application you are/were eyeing at the time? Or was its regulation exceedingly bad?
Oh, I think you need to read my previous thread...
I had a single chicago transfo, which was too weak (i.e. its HV winding's power rating) to supply both channels by alone. It was 488V CT @ 0.07A.

Quote:
Yeah. I think. Uh, something like that. Well look at the layout of a normal FWB. Then replace the top two diodes (which rectify the AC legs into the positive rail) with a 5U4/???.
I'll try to draw a diagram and post it here, so that you guys can double check that it is ok (or SAFE!).



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I've tried thermite before but could never get it burning very well...
What did you use to provide the activation energy? If a single piece of Magnesium is insufficient, try to ignite more Mag's at once... Don't forget to wear your eye protection !!
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Old 28th November 2004, 05:32 AM   #15
Kyle K is offline Kyle K  United States
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Is this what you mean?

http://www.lundahl.se/hybrid_pow.html

I've used this and it works fine. As with any bridge rectifier, you will have to derate the transformer secondary current to about 60% of the AC current rating.
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Old 30th November 2004, 10:37 PM   #16
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Guys

Is this correct? Would it work safely if I connect two of these to the single Transfo. ??
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File Type: jpg hybrid psu.jpg (27.1 KB, 195 views)
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Old 30th November 2004, 10:56 PM   #17
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Quote:
Originally posted by jlsem


Wow - already. Where did you get your degree so fast?
Well, engineer mind... as near as I can tell.


Quote:
Originally posted by jamesjung21

To minimise the interaction or cross-talk between the two channels by using two separate PSU, although both channels are sharing single transformer.
...Even though it goes through the same room....whatever....

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Oh, I think you need to read my previous thread...
I don't read everything, I would quickly go insane here if I tried

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What did you use to provide the activation energy? If a single piece of Magnesium is insufficient, try to ignite more Mag's at once... Don't forget to wear your eye protection !!
Tried arcing with a little MOT modification (20VAC worth of 8AWG) and some pencil leads. Before that I tried heating a can of it amid firebricks, which worked if despite having to get the whole thing a good glow around yellow heat. Don't have any Mg

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Old 30th November 2004, 11:08 PM   #18
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Any comment about the PS at above?
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Old 30th November 2004, 11:12 PM   #19
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Is this correct? Would it work safely if I connect two of these to the single Transfo. ??
Yes that would work just fine. I've used it my preamp and poweramp.
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Old 30th November 2004, 11:25 PM   #20
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Yes that would work just fine. I've used it my preamp and poweramp.
Cheeeeeeers...

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Don't have any Mg
How about putting your deeply-plated car Mag wheels?
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