dual secondary question - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts 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
Reply
 
Thread Tools Search this Thread
Old 11th January 2017, 03:41 AM   #1
gary h is offline gary h  United States
diyAudio Member
 
Join Date: Apr 2006
Location: bay area, california
Default dual secondary question

Hi all,

I'm wondering if the attached schematic is ok. I'm trying to get two 0-50 volt dc supplies, for two mono SE amp boards. I have a xfmr that has dual 35 vac secondaries. My confusion is that I'm not sure if the dual secondaries share the center tap or if they are independent. My understanding is that if they are independent then their voltage is relative. (If not then I would be grounding the 0 of one to the -50 of the other, right?)

Measuring resistance between secondaries all seem to be about 0.1-0.4 ohms.

Thanks for the help, and or advice for how to best do this. Also if it would be better to run the secondaries in parallel and use a single bridge, please advise.

gary
  Reply With Quote
Old 11th January 2017, 03:44 AM   #2
gary h is offline gary h  United States
diyAudio Member
 
Join Date: Apr 2006
Location: bay area, california
this might help:

dual 50v supply.jpg
  Reply With Quote
Old 11th January 2017, 03:51 AM   #3
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by gary h View Post
I'm not sure if the dual secondaries share the center tap or if they are independent. if it would be better
to run the secondaries in parallel and use a single bridge, please advise.
Your schematic looks correct, there are two floating power supplies, each connected with its negative output
to one common ground point, creating two positive voltage supplies.

To check the isolation between the two secondary windings, use your dvm to see if there is an ohmic connection
between them, probably not. Having separate supplies is usually better than one larger one if you have the space,
especially for single-ended amplifiers.

Last edited by rayma; 11th January 2017 at 03:55 AM.
  Reply With Quote
Old 11th January 2017, 09:53 PM   #4
gary h is offline gary h  United States
diyAudio Member
 
Join Date: Apr 2006
Location: bay area, california
thanks for the reply rayma,

can you help me understand how to best connect the power supply to ground then; When these two separate secondary supplies are floated and not connected to earth via the negative rail they each show about 52 vdc unloaded. When I connect the negative rail of each to chassis and earth ground, the lightbulb tester continues to glow and the dc voltage between + and - on both sides starts to climb. I allowed the caps to charge to 90 vdc (both sides) before shutting everything down. My understanding is that the connection between PS and earth/safety ground is ideal at the negative terminal of the first cap. No?

I will search "floating" on this forum

Totally appreciate all the help

gary
  Reply With Quote
Old 11th January 2017, 09:58 PM   #5
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by gary h View Post
can you help me understand how to best connect the power supply to ground then
There must be some unknown connection between the two secondary circuits.
With the power off and discharged, disconnect the ground connections you made,
and connect an Ohm meter between the two secondaries. It doesn't matter which leads,
just between one lead from each winding. There should be an open circuit. I'm guessing there isn't.

Floating means no connection elsewhere.

Last edited by rayma; 11th January 2017 at 10:03 PM.
  Reply With Quote
Old 11th January 2017, 10:06 PM   #6
gary h is offline gary h  United States
diyAudio Member
 
Join Date: Apr 2006
Location: bay area, california
Indeed,

no open circuits. My secondary leads are black and yellow.

Y-Y = 0.8 ohms
Y-B = 0.4 ohms
B-B = 0.2 ohms

So does this mean that I actually have a center tapped Xfmer with twin center tap leads?

thanks for the fast reply

gary
  Reply With Quote
Old 11th January 2017, 10:09 PM   #7
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by gary h View Post
does this mean that I actually have a center tapped Xfmer with twin center tap leads?
There's some kid of connection then. What's the brand and model number of the transformer?
  Reply With Quote
Old 11th January 2017, 10:15 PM   #8
gary h is offline gary h  United States
diyAudio Member
 
Join Date: Apr 2006
Location: bay area, california
I got it from Apex Jr. so it was probably taken from a piece of gear.

It is a Vantas model # 600239 2 x 35V @ 600 VAs
  Reply With Quote
Old 11th January 2017, 10:24 PM   #9
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by gary h View Post
Vantas model # 600239 2 x 35V @ 600 VAs
Can't find any docs on that one. So, disconnect all the secondary leads.
Connect an Ohm meter to one lead. Check the resistance to the other 3 leads.

If measurements to 2 of the 3 other leads aren't an open circuit, there is an unknown connection.
If there is an open for 2 of the 3 leads, then there are indeed two separate secondaries,
but you may have some of the secondary leads miswired.

Would expect that each secondary has one yellow lead and one black lead.
But, if you didn't use the correct black lead for the particular yellow lead,
the wiring would be wrong. You have to use the meter to correctly pair the leads.

Last edited by rayma; 11th January 2017 at 10:30 PM.
  Reply With Quote
Old 11th January 2017, 10:29 PM   #10
gary h is offline gary h  United States
diyAudio Member
 
Join Date: Apr 2006
Location: bay area, california
Thanks,

there are no open circuits for any combination of secondary connections, as listed in previous post, there is minimal resistance between all connections.

This is good to know though, dual secondaries, just like schematics show, will not have any continuity between windings, even given the big magnet they are wrapped around.

How can I determine if this xfmr is good for anything?

gary
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
4 channel +/- from dual secondary Jamh Power Supplies 9 11th February 2016 06:10 PM
Noobie dual secondary question NordicNorm Power Supplies 22 4th October 2011 01:46 PM
dual secondary transformers jesserparker Chip Amps 14 13th January 2007 01:25 PM
dual primary//dual secondary toroid larryg Chip Amps 22 6th September 2006 10:24 PM
zen ver 4 1000va dual 65v secondary question jeanchin2003 Pass Labs 1 1st June 2004 05:05 PM


New To Site? Need Help?

All times are GMT. The time now is 10:37 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki