how to id transformer VA - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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 12th July 2006, 09:56 PM   #1
diyAudio Member
 
Join Date: Jun 2005
Location: dallas
Default how to id transformer VA

I have a number of center tap 120v transformers and while secondary voltage is easy to determine how does one determine the current limit? Second does each channel of say a chip amp require a dedicated PS? and in my case with active x-over can i supply the three amps for that single channel with a dedicated power supply, I would hate to have to build 17 seperate powersupplys for this project! Third all chips being used require +-15 v, need i replicate these for each chip or channel. thank for any help
  Reply With Quote
Old 12th July 2006, 10:44 PM   #2
phn is offline phn  Sweden
diyAudio Member
 
phn's Avatar
 
Join Date: Oct 2004
No need for dedicated PSU. Most would prefer it, but cost gets in the way.

Do you know the watt rating of the trafo? W/V=VA.

Edit: It's good practice using a (or two, +/-) voltage regulator for each chip and mounting them close to the chip. The filter caps before the regulator(s) can still be shared.
  Reply With Quote
Old 13th July 2006, 03:06 AM   #3
diyAudio Member
 
Join Date: Jun 2005
Location: dallas
Default thanks

regretfully the transformer came out of an old amp. large toroid rectified to + -45 volts but no markings to suggest wattage?. on the ps for the chip amps i had a brain fart am using the +-15 v to power the crossover section sorry.
  Reply With Quote
Old 13th July 2006, 08:09 AM   #4
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
The weight is a good first indication of the VA capability.

You can load the transformer, determine iron and copper losses by measuring outgoing and ingoing power. The efficiency will generally be the highest at the nominal power rating.
  Reply With Quote
Old 13th July 2006, 11:45 AM   #5
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
+-45Vdc sounds a bit high for chipamps?
__________________
regards Andrew T.
  Reply With Quote
Old 13th July 2006, 12:02 PM   #6
diyAudio Member
 
Join Date: Oct 2000
Location: The People's Republic of Maryland
If you go to the Plitron http://www.plitron.com/ site, click Standard Toroids, then select Mechanical specifications you can get the dimensions vs. VA rating. You would still have to measure the voltage, but VA will help you determine the current capability.

Here's the direct link: http://www.plitron.com/pages/Products/Std/mechanic.htm
  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
Using mains transformer as output transformer Elias Tubes / Valves 176 11th March 2013 09:35 PM
Modulation transformer for a driver transformer? ironradio Tubes / Valves 6 28th December 2008 05:05 PM
filament transformer vs plate transformer contaxchen Tubes / Valves 10 14th January 2005 10:43 AM
toroid Transformer as power Transformer for tube tone Tubes / Valves 7 11th February 2003 08:57 AM
toroid Transformer as output Transformer for tube preamp? tone Tubes / Valves 15 2nd February 2003 04:36 AM


New To Site? Need Help?

All times are GMT. The time now is 06:47 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2