Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Preventing the inrush current saturation in a toroidal/EI transformer
Preventing the inrush current saturation in a toroidal/EI transformer
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 14th September 2012, 04:30 PM   #111
AndrewT is offline AndrewT  Scotland
Join Date: Jul 2004
Location: Scottish Borders
Default Very Off Topic reply

Originally Posted by nigel pearson View Post
................... Like the old contacts of a motorcycle points system ( HT coil LT side ) . On a motorcycle these were usually damped with a 0.1 uF paper capacitor ..........
not how the switched coil works.
The coil is an inductor passing current when the points (switch) are closed.
The points open on the cam and break the inductor current. That starts a back emf and that emf is multiplied by the other part of the coil into kV of emf that jumps the gap across the spark plug.
If that was all there was to it, that final spark is so short that it does not reliably ignite the mixture.

So they add a cap in parallel to the coil primary. That creates a resonant circuit and instead of damping, it multiplies the output but much more importantly it oscillates and creates a series of sparks . It's the relatively long duration of the series of sparks that ignites the mixture reliably.
regards Andrew T.
  Reply With Quote
Old 14th September 2012, 05:19 PM   #112
nigel pearson is offline nigel pearson  United Kingdom
diyAudio Member
Join Date: Mar 2007
Location: Oxfordshire
Good point if the unintended pun can be allowed Andrew . I suspect I even knew that once upon a time as I used to read endlessly about HT coils . My Honda 900 was said to work better if given 2 extra volts . There were expensive coils that worked on 13.8V as replacements . It was said Honda were being crafty and using it to restrict performance ( the 107 BHP originals were trouble I read ) . I can believe it as with new plugs mine would approach 130 MPH ( in Germany , honest ) . When the plugs were a bit used 110MPH was more typical . Bike magazine raced one and used the extra battery cell . They switched to standard for road use .

The difference of note is the use of a snubber on a switch . The points is just a capacitor ( ? ) and as you say a resonant circuit . Anyone have views on ideal snubber circuits ? 0.1 uF and 100 R is common .

My observation was the spark levels give a clue as to how healthy the relay is in use . The devices are very similar . Relays say > 50 000 operations . A typical motorcar will do that in a few minutes . I suspect relays are good for millions of operations if used with care .
  Reply With Quote


Preventing the inrush current saturation in a toroidal/EI transformerHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
The ultimate Inrush Current Limiter Solution for large Toroidal Transformers tiefbassuebertr Pass Labs 36 9th November 2015 01:00 AM
Inrush current of toroidal transformers hollowman Power Supplies 5 26th March 2008 10:59 AM
Inrush current limiting necessary for EI transformers Bama Slamma Power Supplies 10 6th November 2006 05:08 PM
Inrush current protection for big toroidal transf ? nina Chip Amps 3 19th April 2006 03:40 PM

New To Site? Need Help?

All times are GMT. The time now is 11:18 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio