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

Solid State Talk all about solid state amplification.

bi-circleton
bi-circleton
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 25th May 2018, 05:34 PM   #31
Pascal Nguyen is offline Pascal Nguyen  Australia
diyAudio Member
 
Join Date: Sep 2016
Location: Sydney
Quote:
Originally Posted by kokoriantz View Post
… it is very easy . You have done it wrong .
Thank you for show me the right approach to the PS, I see what you mean by very easy.
I realised the 50VA toroid was for fathoming the circuit and for my learning curve of how to reduce the EMI.
Somehow I had modified the amp, with SMPS for output and the 50VA toroid for driver stage, my shielding is working very fine in comparison with battery DC supply.
I had tried all my possibilities for shielding the toroid, secondary coil grounded one end, mu-metal, GOSS band ...idc flat ribbon.
I found the best (on my bench) is copper screen shield that I had done and RC filter, a comparison spectrum wit batteries had confirmed.

Many thanks and my appreciation for your help

Pascal Nguyen
Attached Images
File Type: jpg 92D55F47-1B36-4163-8B1D-96855AA02F34.jpg (759.7 KB, 277 views)
File Type: jpeg B9DE0E14-0977-4312-820F-C52809D7310B.jpeg (670.2 KB, 267 views)
  Reply With Quote
Old 25th May 2018, 06:00 PM   #32
Pascal Nguyen is offline Pascal Nguyen  Australia
diyAudio Member
 
Join Date: Sep 2016
Location: Sydney
Quote:
Originally Posted by kokoriantz View Post
MossFed ,… The two DNs must function at temperature about 50°C . The heat sink I use is just a sheet of U plied aluminum with shredded edges can install one TO220 inside and the other on the back .
… Yours is gigantic .
I mounted the DNs on main heatsink next to power transistors with a purpose aiming for a quick start with less warm up time.
At cold stage less current flows through DNs, bias to power transistor is higher via R shunt Drain from one DN to Source of the other.
When it reaches 50 deg C, DNS current is higher then at cold stage, so at both ends of R shunt, V bias drops.

Cheers
  Reply With Quote
Old 26th May 2018, 01:19 AM   #33
kokoriantz is offline kokoriantz  Lebanon
diyAudio Member
 
Join Date: Dec 2015
Location: south east asia
I forgot to mention 50°C is channel temperature . Can someone explain please, how to edit a post .
  Reply With Quote
Old 26th May 2018, 03:30 AM   #34
Pascal Nguyen is offline Pascal Nguyen  Australia
diyAudio Member
 
Join Date: Sep 2016
Location: Sydney
Quote:
Originally Posted by kokoriantz View Post
I forgot to mention 50°C is channel temperature . Can someone explain please, how to edit a post .
With the hope that I understood well the transfer curve of the DN2540, my driver is working in the window choosen from cold start 22 deg C to the plateau of 50 deg C.

Cheers
Attached Images
File Type: jpeg FCA56612-829A-4C43-B5F2-217AABF5DAEC.jpeg (405.5 KB, 246 views)
  Reply With Quote
Old 26th May 2018, 05:52 PM   #35
Pascal Nguyen is offline Pascal Nguyen  Australia
diyAudio Member
 
Join Date: Sep 2016
Location: Sydney
Quote:
Originally Posted by kokoriantz View Post
...it is very easy . You have done it wrong .
Follow your instruction, I reshield the 9V coil, I realised that my previous shield was wrong, the foot print of the 9V coil projected on nearly half the core, now it is reduced to lesser than 10%.
Attached Images
File Type: jpg 0B8BF020-962E-4374-9D72-DC387F0170B0.jpg (737.3 KB, 209 views)
File Type: jpg 0A726A90-0DC8-4634-BD4E-4AB2BCD194AF.jpg (645.2 KB, 201 views)
File Type: jpg EBFC76FF-6424-42DA-B12E-8AD560B29DF9.jpg (806.3 KB, 64 views)
  Reply With Quote
Old 29th May 2018, 02:22 PM   #36
Pascal Nguyen is offline Pascal Nguyen  Australia
diyAudio Member
 
Join Date: Sep 2016
Location: Sydney
Quote:
Originally Posted by kokoriantz View Post
... it is very easy . You have done it wrong .
What I have done wrong this time, perhaps some nasty ground loops are witching me. The FFT result is disappointing.

Rondino
Samuel Sanders and Kreisler collection, my favorite, from the rat nest.

YouTube
Attached Images
File Type: jpeg 5DDC524D-F3C9-4260-8140-22BED3020BDE.jpeg (797.7 KB, 53 views)
File Type: jpeg 2548B29A-B46F-40CF-A0E4-586B67A3814F.jpeg (794.6 KB, 30 views)
  Reply With Quote
Old 29th May 2018, 02:45 PM   #37
kokoriantz is offline kokoriantz  Lebanon
diyAudio Member
 
Join Date: Dec 2015
Location: south east asia
600ohms coaxial cable is very thick used by professional fandom 48 v microphones ,for long distance ,as on stages . It has two wires and of course the shield .

To measure the noise captured , you can test the transformer alone by applying 10k ohm on the terminal of the single coaxial carrying both 9v wires, between the shield and one of the 9v . On scope or milli voltmeter you must read zero across the resistor ,if not, check from where it is capturing . Every volt you read, one tenth of it will appear on the output. The ground of this amp is created by the sources of the outputs . With my transistors having their source on the backplate they ground the heat sink naturally . So the coaxial's shield gets grounded by the heat sink. I am 100% offline a month out of two and it will be from 3 June to 5 July .

You are bringing the coaxial wire to the diodes and then a pair of non shielded twisted wires are serving a giant mass of capacitors with bazar of components . All these capture noise . My proto circuit is only 5cm wide 8 cm long carrying the four diodes, two capacitors, bias resistors, the two DNs on same heat sink ,a source resistor for one and an adjust for the other ,plus the volume . The shielded supply arrive ,and Gn Gp depart . That's all.

The noise spectrum looks like that of switching power supply . Earth the heat sink see if it decreases .
  Reply With Quote
Old 31st May 2018, 01:06 PM   #38
Pascal Nguyen is offline Pascal Nguyen  Australia
diyAudio Member
 
Join Date: Sep 2016
Location: Sydney
Quote:
Originally Posted by kokoriantz View Post
600ohms coaxial cable is very thick used by professional fandom 48 v microphones ,for long distance ,as on stages . It has two wires and of course the shield .

To measure the noise captured , you can test the transformer alone by applying 10k ohm on the terminal of the single coaxial carrying both 9v wires, between the shield and one of the 9v . On scope or milli voltmeter you must read zero across the resistor ,if not, check from where it is capturing ...
Follow your advice, two transformers with different kind of shield for 9V coil are measured with 10k Ohm termination from 100 Ohm twisted wires coaxial cable, will build a 600 Ohm câble for the next test.
Far away from zero volt target, the broad shield captures less 50Hz field then the narrow ring shaped.

Cheers
Attached Images
File Type: jpeg 4841D9C4-58AF-4098-94D6-9B19E72A3BF5.jpeg (869.9 KB, 56 views)
File Type: jpeg CFA917E9-8AAD-4F98-B2DF-C8272F664F84.jpeg (865.9 KB, 58 views)
  Reply With Quote
Old 31st May 2018, 02:20 PM   #39
Pascal Nguyen is offline Pascal Nguyen  Australia
diyAudio Member
 
Join Date: Sep 2016
Location: Sydney
Quote:
Originally Posted by MossFed View Post
Follow your advice, two transformers with different kind of shield for 9V coil are measured with 10k Ohm termination from 100 Ohm twisted wires coaxial cable, will build a 600 Ohm câble for the next test.
Far away from zero volt target, the broad shield captures less 50Hz field then the narrow ring shaped.

Cheers
My apologies, the photos annotations are cheating, please read them as:
Broad shield = 0.06Vrms
Narrow shield = 0.14Vrms

Many thanks
  Reply With Quote
Old 2nd June 2018, 10:51 AM   #40
Pascal Nguyen is offline Pascal Nguyen  Australia
diyAudio Member
 
Join Date: Sep 2016
Location: Sydney
Quote:
Originally Posted by MossFed View Post
...will build a 600 Ohm câble for the next test...

Cheers
Not easy, real 600 Ohm cable doesn’t exist. It seems to me that 600Ohm is attributed to the impedance of transformer.
I use an application from Agilent to see how much the radius is if centre core has 1mm diam.
The app can run up to 413 only, but it ran on parallel wires, for 1mm wire, it must be separated at 1.5m with polypropylene as dielectric to achieve 600 Ohm impedance @ 1kHz.

I build a third toroid 9V with single shield on broad footprint.
For zero V 50Hz field inductance as Mr K stated, I think that he uses a double shield “medical grade” (ES + mu métal) power transformer to mount a 9V coil sandwiched shield.

The newly built toroid has 0.008Vrms, single shield, -80dB @ 50Hz.

Bi-Circleton Single Shield 9V coil - YouTube

My apologies for swivel chair noise during the recording.

Cheers
Attached Images
File Type: jpg F8614116-DEFE-4B20-AE5B-D9E699369EEC.jpg (1,014.4 KB, 52 views)
File Type: jpg E76245A5-7394-4ECB-AA4E-BCD578D3181D.jpg (825.4 KB, 50 views)
  Reply With Quote

Reply


bi-circletonHide 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


New To Site? Need Help?

All times are GMT. The time now is 03:19 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
Wiki