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

Planars & Exotics ESL's, planars, and alternative technologies

Diaphragm charging question
Diaphragm charging question
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 8th March 2016, 01:20 AM   #1
Penguin87 is offline Penguin87  United States
diyAudio Member
Join Date: Oct 2009
Red face Diaphragm charging question

I am reading Sanders' book on electrostatics, and have been looking at the many posts here and have a question that I haven't seen come up.

Please bare with me as I am trying to understand it.

If the ESL is being built in a push/pull format, why is the diaphragm only charged on one side? Wouldn't coating both sides and charging both sides increase the effectiveness of the rear stator in helping the front stator to pull or push the diaphragm (given that every design charges the front of the diaphragm, but not the back)?

Has anyone made an ESL with the back side of the diaphragm coated and charged?

OK, let me have it.
  Reply With Quote
Old 8th March 2016, 01:35 AM   #2
moray james is offline moray james  Canada
diyAudio Member
Join Date: Aug 2003
Location: Calgary on the Bow
the diaphragm is so very thin and the charge so very high that the diaphragm does not with any significance impact the charge value on the non connected side. So the simple answer is you don't need to make it more complex you have just as many volts of charge on both sides to do the job.
moray james
  Reply With Quote
Old 8th March 2016, 01:53 AM   #3
Penguin87 is offline Penguin87  United States
diyAudio Member
Join Date: Oct 2009
Ok, that makes sense. Thanks.
  Reply With Quote
Old 8th March 2016, 03:02 PM   #4
bolserst is offline bolserst  United States
diyAudio Member
bolserst's Avatar
Join Date: Jun 2005
Location: Fort Worth, Texas
There was a technical article in the February 1956 issue of Wireless World on this topic.
They author claimed that distortion free operation for large diaphragm excursions could only be obtained if the two sides of the diaphragm were charged thru separate coatings that were insulated from each and fed bias voltage thru independent high resistances.

In the Letters to the Editor in the March 1956 issue, Peter Walker explained that if the capacitance through the diaphragm, from one coating to the other, is large compared to the capacitance between the coatings and adjacent stators then the operating conditions approached those of a single coating on one side of the diaphragm fed through a high resistance. Another letter provides the equations showing why separation of charges on either side of the diaphragm has no advantage over a single conductive side with the same net charge.

Another thing to consider is the mass added to the diaphragm from a second coating. For best high frequency response, you need to keep the moving mass as small as possible.
Attached Files
File Type: pdf ESL_2coatings_WW1956_Article.pdf (883.8 KB, 15 views)
File Type: pdf ESL_2coatings_WW1956_Letters.pdf (877.9 KB, 10 views)
  Reply With Quote
Old 8th March 2016, 07:02 PM   #5
golfnut is offline golfnut  New Zealand
diyAudio Member
golfnut's Avatar
Join Date: Jul 2010
Location: Lower Hutt, NZ
The simples answer, I think, is that the diaphragm material is completely transparent to the electric field.

The electrostatic motor pushing the charges does not care whether the charges are on one surface, the other surface, both surfaces, or distributed through the bulk of the diaphragm. So long as they are attached to the diaphragm, and when they are move, the diaphragm moves with them.
“Nothing is more practical than a good theory.”
– Ludwig Boltzmann
  Reply With Quote
Old 8th March 2016, 07:06 PM   #6
jcx is offline jcx  United States
diyAudio Member
Join Date: Feb 2003
Location: ..
or you could say the sheet of charge on one side only was "off center" by 1/2 the thickness of the diaphragm additionally divided by a factor of ( e_r - 1 ) of the plastic

in other words - by less than any tolerance anyone is likely to achieve
  Reply With Quote
Old 8th March 2016, 07:32 PM   #7
bengel is offline bengel  United States
diyAudio Member
Join Date: Jan 2010
Location: Ohio
Good question, I was kind of curious about this myself.
  Reply With Quote


Diaphragm charging questionHide 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
Seamless charging and use kitehigh Class D 2 6th October 2014 11:30 AM
Battery charging bluejon Parts 17 31st August 2013 02:28 PM
Question about Solar panel charging for my boombox matros Power Supplies 13 17th July 2012 02:05 AM
hi guys just got a quick question about ajustable regulators for battery charging steptoe1111 Power Supplies 14 5th January 2011 05:53 PM
Self Charging Capacitors?! Rarkov Parts 4 6th August 2003 08:06 AM

New To Site? Need Help?

All times are GMT. The time now is 11:58 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio