how to apply transformer snubber to a centre tapped secondary and 2 diode full wave? - 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 29th January 2015, 08:56 PM   #1
dwjames is offline dwjames  United Kingdom
diyAudio Member
 
dwjames's Avatar
 
Join Date: Jun 2012
Question how to apply transformer snubber to a centre tapped secondary and 2 diode full wave?

Hi guys,
what's the recommended method for adding a snubber across the secondary of a transformer if it's centre tapped and being used with a 2 diode full wave rectification?
Do you only need a single snubber across the 2 outer wires, ignoring the centre tap or is it better to have 2 lots of snubbers going to the centre tap like this?
Click the image to open in full size.
I did a bit of searching around but couldn't find a definitive answer.
thanks,
James
  Reply With Quote
Old 29th January 2015, 11:02 PM   #2
diyAudio Member
 
zigzagflux's Avatar
 
Join Date: Oct 2006
Location: Charlotte, NC
A single snubber will suffice, either on the secondary outer leads (my preferred) or on the primary (functions just fine).
  Reply With Quote
Old 30th January 2015, 07:54 AM   #3
diyAudio Member
 
trobbins's Avatar
 
Join Date: Feb 2009
Location: Melbourne, Oz
Although a single snubber may well suffice, the aim of the snubber is to continue to circulate the diode current at the diode turn-off transition - that current is flowing through just half the winding (ie. back o the CT) and so the snubber should ideally be tested for each half winding and applied to each half winding.
  Reply With Quote
Old 30th January 2015, 12:30 PM   #4
diyAudio Member
 
zigzagflux's Avatar
 
Join Date: Oct 2006
Location: Charlotte, NC
Semantics, possibly, but the goal is to continue to circulate transformer winding current, not diode current. If a well chosen diode is selected, diode snubbing creates more problems than it solves. This is transformer snubbing.
With one snubber, you rely on the unused winding's DCR to provide a path for this transient current. Any reasonably or properly sized snubber will have a transformer DCR that does not significantly affect operation of the snubbing action. And this action occurs equally on both winding halves, so if a R value is chosen, it is based on the contribution from the transformer DCR. As an example, if the ideal R value is 100 but the half-winding DCR is 10, you may find the ideal R selected is 90 ohms. It all needs to be selected by test with a scope.

I have checked operation with a scope on multiple designs, and without exception it works. Get closely zoomed into the transient, and a clean smooth waveform is verified. Installation on the primary works just fine too.
  Reply With Quote
Old 30th January 2015, 02:12 PM   #5
diyAudio Member
 
trobbins's Avatar
 
Join Date: Feb 2009
Location: Melbourne, Oz
The importance of snubber position is likely dependant on leakage inductance levels in the windings, as that is the driver of the disturbance being snubbed, and also a hurdle to jump when trying to divert or couple current through other windings. If leakage inductance is low, then yes the diode loop current will easily pass around or couple to any other winding you choose.
  Reply With Quote
Old 31st January 2015, 09:44 AM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
I put the snubber across the secondary at the bridge rectifier, ~ to ~
This is the first and closest opportunity to add the snubber to the secondary winding.
__________________
regards Andrew T.
  Reply With Quote
Old 1st February 2015, 09:33 PM   #7
dwjames is offline dwjames  United Kingdom
diyAudio Member
 
dwjames's Avatar
 
Join Date: Jun 2012
Thanks guys. I'm going to build a cheapmodo circuit and have a play about with that
  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
Use Centre-tapped transformer without using the centre tap...possible? Crom Power Supplies 11 6th December 2013 05:32 PM
FS: 100V dual secondary (centre tapped) 150va? 42v and 33v transformer alan1977 Swap Meet 0 24th October 2013 02:58 PM
Full wave centre tap versus bridge alibear Power Supplies 12 25th September 2013 02:23 PM
Full Wave Rectifiers: Center Tapped vs. Bridged Astera Tubes / Valves 20 20th July 2013 11:42 AM
What's the biggest full wave damper diode? leadbelly Tubes / Valves 12 10th September 2008 07:39 PM


New To Site? Need Help?

All times are GMT. The time now is 11:28 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2