This power supply ok?

CarlyBoy · 28th December 2008, 05:01 PM

Anyone see any problems with the following supply? I’m trying to use a power transformer that has no secondary center tap. V1 and V2 will be TV dampers of the same type and are present to provide a B+ delay while the filaments warm up.

Iain McNeill · 28th December 2008, 05:39 PM

D3 is in parallel with D5, D6 in parallel with D1. The full secondary voltage is presented to B+1 and ground through the bridge. Your B- will be at best, 0V.

Sorry, this won't work.

CarlyBoy · 28th December 2008, 06:42 PM

Thanks, Iain. I might be overthinking this. Is the following any better?

Tony · 28th December 2008, 07:41 PM

no....won't work...sorry, you B- will still be 0....

Iain McNeill · 28th December 2008, 07:46 PM

Yes, that performs equally well for less cost

Your only options are:
A: to split the bridge output using resistors (as you are doing for B+1 and B+2) Then the bridge output provides B+1 and B-, you use resistors to create 0V and B+2. This is messy, wastes power and creates soggy(high impedance) rails.

B: use some kind of switched mode PSU to create the -ve additional rail from the B+1 rail. If B+1 is high voltage then this is ugly.

C: get a proper transformer.

Sorry, but a single winding really only produces a single rail. There's no free lunch even when you DIY

CarlyBoy · 28th December 2008, 11:56 PM

Will a second HV winding help? How's the following?

astouffer · 29th December 2008, 12:05 AM

http://www.aikenamps.com/BackBiasing.html

DigitalJunkie · 29th December 2008, 12:28 AM

Quote:

Originally posted by astouffer
http://www.aikenamps.com/BackBiasing.html

I was just going to suggest that little trick.

Tom Bavis · 29th December 2008, 01:22 AM

How much B- current do you need? You may be able to use a half-wave rectifier capacitor coupled to one end of the winding.

CarlyBoy · 29th December 2008, 02:26 AM

Interesting article on back-biasing, but I unless I'm missing something this won't work in this case since my secondary winding has no center tap.

Tom, current will not exceed 10 ma. Is that within reason for what you're suggesting?

28th December 2008, 05:01 PM	#1
CarlyBoy diyAudio Member Join Date: Aug 2006	This power supply ok? Anyone see any problems with the following supply? I’m trying to use a power transformer that has no secondary center tap. V1 and V2 will be TV dampers of the same type and are present to provide a B+ delay while the filaments warm up.

28th December 2008, 07:41 PM	#4
Tony diyAudio Moderator Join Date: May 2003 Location: Palatiw, Pasig City	no....won't work...sorry, you B- will still be 0.... __________________ http://www.elab.ph/forum/index.php?topic=32688.0

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Split Voltage Switching Power Supply for Power Amp	vectorplane	Swap Meet	2	23rd April 2011 11:48 PM
LTspice tool for power amp power supply component evaluation	andy_c	Software Tools	2	23rd August 2009 05:10 PM
Can i use a computer power supply to power audio amplifiers?	destroyer X	Solid State	91	25th September 2006 04:36 AM
selling high current power supply for power amps.	ericpeters	Swap Meet	0	14th January 2005 02:21 PM
heater supply (xformer specs are 6.3V 2.5A) as supply for a power LED?	jarthel	Tubes / Valves	10	21st July 2003 01:30 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

28th December 2008, 05:39 PM	#2
Iain McNeill diyAudio Moderator Emeritus Join Date: Oct 2007 Location: Santa Cruz, California	D3 is in parallel with D5, D6 in parallel with D1. The full secondary voltage is presented to B+1 and ground through the bridge. Your B- will be at best, 0V. Sorry, this won't work.

28th December 2008, 06:42 PM	#3
CarlyBoy diyAudio Member Join Date: Aug 2006	Thanks, Iain. I might be overthinking this. Is the following any better?

28th December 2008, 07:46 PM	#5
Iain McNeill diyAudio Moderator Emeritus Join Date: Oct 2007 Location: Santa Cruz, California	Yes, that performs equally well for less cost Your only options are: A: to split the bridge output using resistors (as you are doing for B+1 and B+2) Then the bridge output provides B+1 and B-, you use resistors to create 0V and B+2. This is messy, wastes power and creates soggy(high impedance) rails. B: use some kind of switched mode PSU to create the -ve additional rail from the B+1 rail. If B+1 is high voltage then this is ugly. C: get a proper transformer. Sorry, but a single winding really only produces a single rail. There's no free lunch even when you DIY

28th December 2008, 11:56 PM	#6
CarlyBoy diyAudio Member Join Date: Aug 2006	Will a second HV winding help? How's the following?

29th December 2008, 12:05 AM	#7
astouffer diyAudio Member Join Date: Jun 2004 Location: Pittsburgh, crumbling wasteland	http://www.aikenamps.com/BackBiasing.html

29th December 2008, 01:22 AM	#9
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	How much B- current do you need? You may be able to use a half-wave rectifier capacitor coupled to one end of the winding.

29th December 2008, 02:26 AM	#10
CarlyBoy diyAudio Member Join Date: Aug 2006	Interesting article on back-biasing, but I unless I'm missing something this won't work in this case since my secondary winding has no center tap. Tom, current will not exceed 10 ma. Is that within reason for what you're suggesting?