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

Juma's Easy-Peasy Capacitance Multiplier
Juma's Easy-Peasy Capacitance Multiplier
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 13th October 2016, 12:16 PM   #1
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Juma's Easy-Peasy Capacitance Multiplier
Default Juma's Easy-Peasy Capacitance Multiplier

I have built many amps and have been working on improving my power supply ripple with the usual CRC or CRCLC circuits. My best effort was actually an Abletec SMPS followed by a CRC where I got 1mV ripple under quisescent bias current. With linear toroidal transformers, I could never get below maybe 5mV and that was with a lot of effort. However, in class A, start pulling a couple of amps and that rises to 20mV sometimes 100mV depending on your trafo and CRC filter setup.

Novi amp sa 2SK2013/2SJ313 - Solid State - diyAudio.rs

Juma's cap multiplier:

Click the image to open in full size.

Here is nice schematic of the basic core cap Mx for a single rail use by Jwksana:
Click the image to open in full size.

I recently built a small class A designed by Juma based on the Pass F5 but using the little 2SK2013/2SJ313 MOSFETs in parallel.

F5 with 2SK2013/2SJ313

The amp works well and sounds very nice. It draws about 1.5amps continuously and I am feeding it with my usual class A power supply: a 400VA 18VAC Antek with a 33mF/0.12R/33mF CRC. I was measuring 20mV ripple per rail and audible hum was coming through when no music was playing.

Juma's plans for the little F5 also included a simple capacitance multiplier circuit. It was so simple I had to try it. I have tried others in the past but they were always more complex and typically used BJT's and Darlingtons that I did not have on hand. This one however uses a single IRFP240/9240 per rail, a few resistors and easy to find caps, and a diode. It was so simple I could P2P on the legs of the MOSFET sticking up in the air:

Click the image to open in full size.

I powered it up, now fed from my usual CRC that had 20mV ripple under load. There is a 2v voltage drop so you will lose some headroom. However, if you plan ahead, just get a slightly higher voltage secondary rating transformer. Then I hooked it up to the amp and adjusted bias current to usual 1.5amps and now measured the ripple...

Cap multiplier under test with F5 amp and 1.5amps flowing:

Click the image to open in full size.

I was floored to see the Fluke AC volts drop to 0.000V AC (across +/- rails at 40v total). Sometimes flickered to 1mV then back to zero again (Fluke 101 has 1% accuracy of measured value + 3, the number added to the least significant digit, data valid over 40Hz to 500Hz range). I would love to have an o-scope to see what it really is doing - but there was a significant improvement in the sound quality. The hum was gone. I will try in my class AB amps next but thought folks might like to try this. It is dead simple and so easy. Anyhow, I think I will be making many more of these in the future and a little PCB would be handy. Just wanted folks to know about what a great circuit this is and to give it a thumbs up! Thanks to Juma for designing it.

If you have any experience with cap multipliers, please share. I have seen the ESP one and the one by Keantoken. This one with a single MOSFET is the easiest one I have seen though.

Edit Nov 13, 2016: stereo cap multiplier on one heatsink.

Click the image to open in full size.

Here is a really nice one by Olafk:

Click the image to open in full size.

Nice 4 cap Mx on 100mm square PCB by Prasi:
Click the image to open in full size.

Gerbers on post 245

Here is another nice one by Prasi for use with external bridge block:
Click the image to open in full size.

Last edited by xrk971; 15th October 2017 at 06:30 PM.
  Reply With Quote
Old 13th October 2016, 12:49 PM   #2
Mark Johnson is offline Mark Johnson  United States
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
Juma's Easy-Peasy Capacitance Multiplier
Maybe these other MOSFETs would work even better in Juma's circuit design. They are rated for much greater current and much greater power dissipation.

_
Attached Images
File Type: png NMOS.png (59.1 KB, 2121 views)
File Type: png PMOS.png (59.6 KB, 1759 views)
  Reply With Quote
Old 13th October 2016, 01:31 PM   #3
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Juma's Easy-Peasy Capacitance Multiplier
Quote:
Originally Posted by Mark Johnson View Post
Maybe these other MOSFETs would work even better in Juma's circuit design. They are rated for much greater current and much greater power dissipation.

_
Those are interesting MOSFETs. 80amps - wow! I doubt you can safely pull 80amps through a TO-220 without smoking it. How much heat dissipation is that? Assuming 2v drop x 80amp is 160w!

I don't think there is an issue with current yet - 12amps with IRP240/9240 is quite high already. I don't know too many amps that pull that much current.

Main reason for me is that I literally have a drawer full of them already. My favorite MOSFET.

Last edited by xrk971; 13th October 2016 at 01:35 PM.
  Reply With Quote
Old 13th October 2016, 02:27 PM   #4
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Juma's Easy-Peasy Capacitance Multiplier
These are very effective ripple filters, the only downside is the loss of headroom. This shows a load current of around 650ma. You can see how small the ripple is, but also the loss in headroom.
Attached Images
File Type: png Ripple.PNG (49.9 KB, 1746 views)
File Type: png Ripple 2.PNG (49.9 KB, 1471 views)
  Reply With Quote
Old 13th October 2016, 02:44 PM   #5
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Juma's Easy-Peasy Capacitance Multiplier
Hi Mooly,
Thanks for the simulation! Wow - that is indeed very effective and confirms my experience and data from the Fluke. I was wondering if it was just missing bandwidth but this appears to be a very sound topology. Loss of headroom probably not an issue for someone wishing to listen to music as lower volumes where hum is audible.
  Reply With Quote
Old 13th October 2016, 03:16 PM   #6
dobrivoje is offline dobrivoje  Serbia
diyAudio Member
 
Join Date: Aug 2009
Location: Smederevo, Serbia
Most of Juma's amps have PSU with cap mutiplier. You can see attached some examples.
The last one is with BJT if you need less voltage drop (2.1V compared to 4V drop with MOSFETs).
Attached Images
File Type: gif Cubie_PSU-AMP-PCB.gif (81.2 KB, 7860 views)
File Type: gif cubie-cm.gif (10.2 KB, 1797 views)
File Type: gif post-20-0-57622100-1298065429.gif (26.0 KB, 1679 views)
File Type: gif C3-PSU-sch.gif (8.3 KB, 1683 views)
File Type: gif cmbjt.gif (3.9 KB, 1676 views)
  Reply With Quote
Old 13th October 2016, 03:19 PM   #7
Mark Johnson is offline Mark Johnson  United States
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
Juma's Easy-Peasy Capacitance Multiplier
Mooly's expression "loss in headroom" can be translated "enormous voltage drop from Vin to Vout; notice that Vout is 4 volts below Vin!!"

This is a result of using "standard" gate threshold MOSFETs whose Vth is about 4 volts. "Logic Level" gate threshold MOSFETs would reduce the voltage drop to about 2 volts, and of course bipolar power transistors would lower it to 0.7 volts. Keantoken's Complementary Feedback Pair ("Sziklai") capacitance multiplier has a Vin-to-Vout drop of about 1.4 volts, as does a two transistor darlington-connection.
  Reply With Quote
Old 13th October 2016, 03:22 PM   #8
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Juma's Easy-Peasy Capacitance Multiplier
Click the image to open in full size.

This is like an F5 with the venerable 2SK1058 and 2SJ162 lateral FET. Will have to try it one day.
  Reply With Quote
Old 13th October 2016, 03:26 PM   #9
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Juma's Easy-Peasy Capacitance Multiplier
Thanks for brining up lower dropout voltage options. I may have try them but for most cases I am not at a loss for head room for home use at moderate listening levels. IRFP's have a very low Rdson and perhaps have an advantage in instantaneous transient current response for more bass impact?
  Reply With Quote
Old 13th October 2016, 03:34 PM   #10
Mark Johnson is offline Mark Johnson  United States
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
Juma's Easy-Peasy Capacitance Multiplier
Quote:
Originally Posted by xrk971 View Post
IRFP's have a very low Rdson and perhaps have an advantage in instantaneous transient current response for more bass impact?
I doubt that your capacitance multiplier circuit would ever operate the MOSFETs in the Rdson regime (huge Vgs, tiny Vds) but if it somehow happened:

Code:
Device     Polarity   RDSon
-------------------------------
IRFP240    Nch        0.180 ohms
STP75NF75  Nch        0.011 ohms

IRFP9140   Pch        0.200 ohms
SPP80P06   Pch        0.023 ohms
  Reply With Quote

Reply


Juma's Easy-Peasy Capacitance MultiplierHide 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
My experience with a Capacitance Multiplier Shoog Pass Labs 29 5th September 2010 06:02 PM
Capacitance Multiplier PSU Ted205 Chip Amps 3 2nd March 2009 01:27 PM
Capacitance Multiplier Kinnja Solid State 2 13th January 2008 08:12 PM


New To Site? Need Help?

All times are GMT. The time now is 12:24 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