Quick question about CT and FWB

athos56 · 2nd May 2009, 02:09 AM

I have a 40VCT (20 - 0 - 20) transformer that I'm using to make a 40v PSU with a FWB rectifier, what I need to know is, what do I do with the CT? Whats the difference between grounding it and leaving it unconnected? I tried to search but the search engine wasn't very helpful.

HollowState · 2nd May 2009, 02:29 AM

Do not connect the CT to anything. Protect it form touching anything by folding it and either taping it up or slide a piece of heat shrink tubing over it. If you used the CT, you could get ± 20V.

Tom Bavis · 2nd May 2009, 02:30 AM

DO NOT ground it if you will have either end of the bridge connected to ground.

athos56 · 2nd May 2009, 03:04 AM

Quote:

Originally posted by HollowState
Do not connect the CT to anything. Protect it form touching anything by folding it and either taping it up or slide a piece of heat shrink tubing over it. If you used the CT, you could get ± 20V.

This is what I did, I just had a moment of confusion. New baby=no sleep=maybe I should check all my work, twice.

Thanks for answering the simple question of the night.

Richard Ellis · 2nd May 2009, 03:33 AM

Are you a newbie at PS design?? As in, you won't get an exact 40VDC from this transformer.
Appx 56VDC for straight Cap.
36 VDC for choke input design OR
40 VDC straight cap plus regulation

My apologies for noting this if your already aware.
_________________________________________________R ick....

athos56 · 2nd May 2009, 04:27 AM

This will be my 6th one. Although it is the first solid state FWB PSU I've made, hence the moment of confusion. I have a few RC filters to bring the voltage down and I'm not concerned with 10% (+/- 4v) error, which I've found isn't noticeable, at least to me. I got it sim'd out with PSUD II as well. Thanks for checking though

It is a psudo-dual mono supply with 2 small chokes in some LC filters at the split, followed by a few RC filters and a gyrator at the end (as an experiment) to kill what ever ripple is left.

2nd May 2009, 02:09 AM	#1
athos56 diyAudio Member Join Date: May 2006 Location: Yakima, Washington	Quick question about CT and FWB I have a 40VCT (20 - 0 - 20) transformer that I'm using to make a 40v PSU with a FWB rectifier, what I need to know is, what do I do with the CT? Whats the difference between grounding it and leaving it unconnected? I tried to search but the search engine wasn't very helpful.

2nd May 2009, 02:29 AM	#2
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	Do not connect the CT to anything. Protect it form touching anything by folding it and either taping it up or slide a piece of heat shrink tubing over it. If you used the CT, you could get ± 20V. __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

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2nd May 2009, 02:30 AM	#3
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	DO NOT ground it if you will have either end of the bridge connected to ground.

2nd May 2009, 03:33 AM	#5
Richard Ellis diyAudio Member Join Date: Sep 2006 Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.	Are you a newbie at PS design?? As in, you won't get an exact 40VDC from this transformer. Appx 56VDC for straight Cap. 36 VDC for choke input design OR 40 VDC straight cap plus regulation My apologies for noting this if your already aware. _________________________________________________R ick....

2nd May 2009, 04:27 AM	#6
athos56 diyAudio Member Join Date: May 2006 Location: Yakima, Washington	This will be my 6th one. Although it is the first solid state FWB PSU I've made, hence the moment of confusion. I have a few RC filters to bring the voltage down and I'm not concerned with 10% (+/- 4v) error, which I've found isn't noticeable, at least to me. I got it sim'd out with PSUD II as well. Thanks for checking though It is a psudo-dual mono supply with 2 small chokes in some LC filters at the split, followed by a few RC filters and a gyrator at the end (as an experiment) to kill what ever ripple is left.