Tapping a main toroidal - 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
Thread Tools Search this Thread
Old 7th May 2011, 10:23 PM   #1
akis is offline akis  United Kingdom
diyAudio Member
Join Date: Jul 2008
Default Tapping a main toroidal

I have an 80VA 2x25V / 1.6A mains toroidal which I am planning to use for a simple bench PSU. The panel instruments need 5V and so I thought of winding some enameled copper wire around the toroidal aiming for 5V DC under moderate load (big LED segment displays).

I pulled out a random length of wire and wound it around, did not count the turns, and measured approx 3.8V DC after rectification + filter. I unwound the wire, measured the length, and then cut a new piece twice as long. This gave me 4.2V DC. I cannot understand this. I pulled it out and re-wound it the other direction, much more carefully and more evenly than before, and measured 4.4V DC.

How can double the length of wire (hense double the turns) not give me double the voltage?
  Reply With Quote
Old 8th May 2011, 02:51 AM   #2
diyAudio Member
Join Date: Nov 2010
Location: N.E. PA
First measure the ac voltage, not dc, for comparison.

Second it is the number of turns, not the length. The circumference may not be constant.

  Reply With Quote
Old 8th May 2011, 07:42 AM   #3
akis is offline akis  United Kingdom
diyAudio Member
Join Date: Jul 2008
I added another length and I have gone over 5.5AC. Happy now.
  Reply With Quote


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
tapping differential outputs belgiangenius Digital Line Level 4 8th July 2010 07:25 PM
Amplimo Main TX toroidal typ 2N1357 dvb projekt Swap Meet 1 29th November 2009 09:06 AM
Tapping master clock habsrock93 Digital Line Level 10 8th November 2008 01:41 AM
Best Transformers (Encapsulated Toroidal or Open Frame Toroidal) Rixsta Pass Labs 10 23rd April 2004 03:41 AM
drilling/tapping aluminum elizard Parts 32 6th March 2004 06:18 AM

New To Site? Need Help?

All times are GMT. The time now is 11:48 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