Power transformer question, any helpful suggestions welcome - 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 7th June 2012, 11:41 PM   #1
diyAudio Member
 
Join Date: Apr 2012
Exclamation Power transformer question, any helpful suggestions welcome

I have a (big) transformer I salvaged, the primary wires are L/ground/N and scondary provides 2 reds a red with white stripes-/+55v (wich I dont plan on getting anywere near) 2 blue and a blue with white stripes -/+ 14.3v. Im planning to power an amp to add a good boom to my house sound system, Im using my car amp, i have the transformer wired into a 50a bridge rectifier, and. Just beacause I have them and never used them before i connected a big 10,000uF 75vdc cap, wich then I connected to the amp, i had my multimeter connected at the connecting strip and i tried powering it no sound comes out and the amp goes straight into protect mode, the meter read 16-18v dc. I thought about putting a L7812cv i have but it only does 1a tops. Any advise would be greatly appreciated. I know the risks I run and I do take necesary pracautions. HELP PLEASE
  Reply With Quote
Old 8th June 2012, 02:36 AM   #2
diyAudio Member
 
Join Date: Apr 2012
To make a long story short I need a way to regulate voltage. And suggestions on the power supply, additions or anything helpful
  Reply With Quote
Old 8th June 2012, 06:20 PM   #3
spwalek is offline spwalek  United States
diyAudio Member
 
Join Date: Mar 2012
Location: West Seneca NY
Do a search on 7812 circuits with a pass transistor for current boosting. I had to do something similar for my toolbox amp.

Good Luck
  Reply With Quote
Old 8th June 2012, 07:01 PM   #4
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

If its a normal audio transformer, the high voltage rails are also high
current rails, and the low voltage rails are also low current, for the
pre-amp stages, and they simply won't drive a power amplifier.

You'll probaby end up just burning out the low voltage rails.
Measure the DC resistance of each secondary and report back.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
  Reply With Quote
Old 9th June 2012, 06:59 AM   #5
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
Quote:
Originally Posted by GHeTToNoMiKS View Post
I have a (big) transformer I salvaged, the primary wires are L/ground/N and scondary provides 2 reds a red with white stripes-/+55v (wich I dont plan on getting anywere near) 2 blue and a blue with white stripes -/+ 14.3v. Im planning to power an amp to add a good boom to my house sound system, Im using my car amp, i have the transformer wired into a 50a bridge rectifier, and. Just beacause I have them and never used them before i connected a big 10,000uF 75vdc cap, wich then I connected to the amp, i had my multimeter connected at the connecting strip and i tried powering it no sound comes out and the amp goes straight into protect mode, the meter read 16-18v dc. I thought about putting a L7812cv i have but it only does 1a tops. Any advise would be greatly appreciated. I know the risks I run and I do take necesary pracautions. HELP PLEASE
how big is big? try using a variac to lower the voltages...
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  Reply With Quote
Old 9th June 2012, 06:19 PM   #6
cbdb is offline cbdb  Canada
diyAudio Member
 
Join Date: Oct 2008
Location: Vancouver
Whats the max current the transformer will supply? Easiest way to go; (depending on the current output),use a large (50 watt) zener (or two), or a string of regular diodes (might be cheaper and not need a heat sink) to clamp the voltage.

Just string 22 of these together, no heat sink required. Amazon.com: 10 Amp 1000V Axial Diode Rectifiers (Pack of 30): Everything Else

You dont need a regulated supply, the amp will do that itself, so the regulator circuit would be overkill. And a lot more complicated (you would need a large power transitor)

Last edited by cbdb; 9th June 2012 at 06:26 PM.
  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
Newbie Question - Power Transformer vs Isolation Transformer SparkyPete Tubes / Valves 10 2nd November 2012 06:13 PM
Power Transformer Question denny9167 Tubes / Valves 6 15th January 2012 09:31 PM
suggestions for new power supply transformer eduard Power Supplies 0 15th June 2008 11:58 AM
transformer power question needtubes Parts 2 9th April 2004 11:13 AM


New To Site? Need Help?

All times are GMT. The time now is 03:42 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