Keantoken's CFP cap multiplier - Page 22 - 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 10th December 2012, 12:03 PM   #211
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
I have got it....Very instructive.... Thank you.

Can it be used before a LM317 to create a superreg?
__________________
RC
  Reply With Quote
Old 10th December 2012, 02:16 PM   #212
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
I'm not sure why the page wouldn't load, but my friend has a rather special DIY network security system, so maybe it doesn't like you. I will have to speak with him on this. The link is valid, and loads for me.

Using the Kmultiplier before the chipreg is a great way to boost RF input rejection.

The K Multiplier
  Reply With Quote
Old 10th December 2012, 02:24 PM   #213
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Thank you.

I have been using a "normal" cap multiplier before the ship to create good 5v regs for my DAC.

Can I use the circuit as per your site schematic for a +5v reg also ?
__________________
RC
  Reply With Quote
Old 10th December 2012, 03:24 PM   #214
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
Quote:
Originally Posted by jameshillj View Post
Hello Iko,

Nice page, KMultipliers.
Not Iko, keantoken!

1.6A steady is getting into wary territory. At this point outputs are generally too slow and Hfe is too low to be unconditionally stable and still have low output impedance. In simulation this is looking like it can work.

The MJE200/210 seem like reasonable transistors in this current range, and while the MJE15033/32 are more robust they are morbidly slow in comparison. Ultimately I would need to test the circuit myself to see if it is viable. You will certainly not get all the performance at 1A that you can get from the standard Kmultipliers at 100mA.

Luckily, both Cordell and Andy_C have provided custom simulation models for the MJE13032/33 pair, so I'm reasonably sure this is the best solution. Again to be sure, I will need to test it myself or have you take some simple measurements.

For best performance the diode string needs another diode. It's not necessary but it helps.

It will help to know what is the pk-pk input ripple voltage at the point you are intending to put the Kmultipier.

EDIT: Added schematic.
Attached Images
File Type: png Screenshot.png (121.7 KB, 232 views)

Last edited by keantoken; 10th December 2012 at 03:31 PM.
  Reply With Quote
Old 10th December 2012, 03:27 PM   #215
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
Quote:
Originally Posted by RCruz View Post
Thank you.

I have been using a "normal" cap multiplier before the ship to create good 5v regs for my DAC.

Can I use the circuit as per your site schematic for a +5v reg also ?
Definitely. It works at any rail voltage, C1 needs to be rated for that voltage.
  Reply With Quote
Old 10th December 2012, 03:28 PM   #216
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by keantoken View Post
...............1.6A steady is getting into wary territory. At this point outputs are generally too slow and Hfe is too low...............
would a medium power mosFET suit better?
How would the circuit be modified to accommodate a FET pass transistor?
__________________
regards Andrew T.
  Reply With Quote
Old 10th December 2012, 03:34 PM   #217
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
The Kmultiplier NEEDS to have BJTs for high transconductance or it cannot have low Zout, high PSRR, and low voltage drop all at once. It could be modified to use FETs, but then it would not be nearly so useful.
  Reply With Quote
Old 10th December 2012, 10:46 PM   #218
diyAudio Member
 
Join Date: Feb 2005
Ah "keantoken", sorry about that.

Those MJ200/210 are 'tuff' little things for sure - I wonder if it would be possible to use 2 in //, and reduce the strain on them without 'current hogging', etc?

Probably better to just reduce the current, I guess to about the usual 1.3A, or less.

The Power Supply is a good quality (Tortech) 600Va torroidal Txr (for both channels) 21v AC, -> byv27 diode bridges -> 4,700uF Siemens B41455 -> 0.1R -> 12,000uF 'Elna for Audio' -> IRFP240/9240 CMx -> 10,000uF SlitFoils.

Dressed this up with Schaffner line filter, CL-60s, basic dc trap, transformer tuning, R-C snubbers, good & short wiring, dc protection/delay, and so on.
__________________
... jh
  Reply With Quote
Old 11th December 2012, 12:28 AM   #219
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
Sounds like you've got an advanced passive PSU section.

I thought of paralleling outputs, but the MJE200/210 are still very nonlinear and not working very well at low Vce. The MJE15032/33 on the other hand worked as well as I could hope for up to the max current, with the exception of speed. Of course this is in simulation.

I tried MJE240/250 and there was a surprising reduction in PSRR. So good Vcesat specs for the output transistor are important. And this doesn't simply mean having low Vcesat; it also has to have high Early voltage. In the OnSemi models it is very low. I don't know if they can work well even if paralleled.
  Reply With Quote
Old 11th December 2012, 02:23 AM   #220
diyAudio Member
 
Join Date: Feb 2005
Power supply the result of "long time fiddle" and chasing up "good bits" over long time.

The F5 amp is quite sensitive to power supply quality and it's relatively simple to alter the amp's sound via the supply component changes, and a little extra effort - the good quality parts make it easier, except for the size of the final product.

I'm playing around with a simple regulated version (as per Aleph style zener reg) but for all the extra heat and power loss, there isn't that much improvement to the sound, even with all the good caps throughout - a bit disappointing actually. [I may have missed something in the build, perhaps ...] and I'm quite interested to see what your much more sophisticated cct will do in same amp.

It looks like most of these adequate transistors aren't quite suitable for the higher current load - too easy!

I had a weird thought, maybe totally off target - in the F3 amp, there is a little super Jfet (Lu1014) operating with a cascoded power Fet (IRFP240 )- would these items be at all suitable for operations in the Kmx? (I've still got a few left, you see!)
__________________
... jh
  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
Vbe multiplier - bypass cap Donk Solid State 7 22nd January 2008 01:55 AM
Question(s) about CFP. Justcallmedad Solid State 94 20th September 2005 10:08 AM
cap multiplier or not? PederBass Solid State 13 23rd March 2004 06:26 PM
Cap. multiplier or regulated supply ? Buhl Pass Labs 1 8th October 2003 10:51 PM


New To Site? Need Help?

All times are GMT. The time now is 10:37 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2