Testing transformer output - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 8th January 2002, 09:20 AM   #1
diyAudio Member
 
Join Date: Dec 2001
Location: Howick South Africa
Default Testing transformer output

To all the clever ones out there.

I recently obtained about 40 tiroidal transformers from obsolete computor monitors, and rectified they produce about 30 volt under load. I have in the past wired two in series and used them to power two ESP 60 Watt amps, and they performed well, voltage dropping from about 63 to 60 whith both amps working hard. The transformers have no power rating printed on them.

Is it possible to determine how much current I can safely pull from these transformers? I am presently building two bridged amps (ESP 60 watter) and would like to know if I need to have separate supplies, or if two of the transformers will survive.

I am also considering using 4 of them in series to provide a +60 - 60 volt supply for a 350 Watt amp I have built.

Any suggestions?

Dieterd
  Reply With Quote
Old 8th January 2002, 09:34 AM   #2
Warp Engineer
On Holiday
 
AudioFreak's Avatar
 
Join Date: Oct 2001
Location: Queensland, Australia
do you know the VA rating of the transformers?
  Reply With Quote
Old 8th January 2002, 11:33 AM   #3
diyAudio Member
 
Join Date: Dec 2001
Location: Howick South Africa
No , thats the problem, the transformers dont have any ratings on them, and i want to know if there is any (easy) way of testing them.
  Reply With Quote
Old 8th January 2002, 01:07 PM   #4
Warp Engineer
On Holiday
 
AudioFreak's Avatar
 
Join Date: Oct 2001
Location: Queensland, Australia
If the transformers dont have a VA rating marked on them, the only way to get a rough idea of what the VA rating probably is is to run them under a resistive load till the rails start to sag then work out the VA that was required... the VA rating of the transformer was probably near to this figure.
  Reply With Quote
Old 8th January 2002, 01:41 PM   #5
paulb is offline paulb  Canada
diyAudio Member
 
Join Date: Jun 2001
Location: Calgary
The voltage sag check, yes, but also check the temperature of the transformer as you're doing it. Run it for a while at what you think is the VA rating to ensure it doesn't get extremely hot.
  Reply With Quote
Old 8th January 2002, 01:45 PM   #6
Warp Engineer
On Holiday
 
AudioFreak's Avatar
 
Join Date: Oct 2001
Location: Queensland, Australia
Good point paul... I was relying on the fact that most transformers sag noticeably by a few volts before they get hot, but definately check this also.
  Reply With Quote
Old 9th January 2002, 09:56 AM   #7
diyAudio Member
 
Join Date: Dec 2001
Location: Howick South Africa
Thanks,
What % sag is acceptable, these transformers lose about 3 volts from 63 - 60 when working but it seems to stabalise at that. That represents about 5% is that ok.

What exactly is a resistive load, I presume it must be adjustable so that one can load the transformer progressivly untill it get hot or sags?
  Reply With Quote
Old 9th January 2002, 10:42 AM   #8
diyAudio Member
 
Join Date: Sep 2001
Location: Finland, Ostrobothnia
There is also the possibility to estimate or measure the core area and compare to core area/VA-rating of known transformers. Unfortunately I do not have any specs for toroids (VA-rating vs core area). There are also different materials with different characteristics.
  Reply With Quote
Old 9th January 2002, 11:07 AM   #9
diyAudio Member
 
wuffwaff's Avatar
 
Join Date: Aug 2001
Location: Ingolstadt Germany
Hi Dieterd,


you could also put them on a scale and look at there weight. This you could compare with existing lists from manufacturers. It will give you the approx. VA rating.

william
  Reply With Quote
Old 9th January 2002, 11:39 AM   #10
diyAudio Member
 
wuffwaff's Avatar
 
Join Date: Aug 2001
Location: Ingolstadt Germany
http://www.betschart-trafo.com/deutsch/menu2/2/rt.htm

here´s a list with VA ratings and weight for standard torodial transformers

william
  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
transformer testing via DM? spirus Parts 5 31st December 2012 10:57 AM
Testing the transformer for the first time Tripmaster Chip Amps 21 6th May 2008 04:22 PM
Testing a 70.7v transformer astouffer Tubes / Valves 1 6th April 2006 04:40 PM
Transformer Testing SteveS Solid State 3 6th March 2002 11:53 PM
Testing JLH, zero DC output? chris ma Solid State 0 4th September 2001 03:50 PM


New To Site? Need Help?

All times are GMT. The time now is 07:34 AM.


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