Power Supply Capacitors
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

 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
 14th November 2002, 06:30 PM #1 awhiteguy diyAudio Member   Join Date: Oct 2002 Location: Oklahoma Power Supply Capacitors Let's say I want to put 40000uf of filter caps on each voltage rail. I need them to be 100v caps. Assume I have these two options available: 1. one 100v, 40000uf cap for each rail 2. two 50v, 40000uf cap in series for each rail Option 2 is cheaper, which is the direction I'm leaning. Are there any disadvantages to using two 50v caps in series to make a 100v cap? awhiteguy
 14th November 2002, 06:58 PM #2 Variac   diyAudio Editor     Join Date: Dec 2001 Location: San Francisco, USA San José, Costa Rica I don't think 2 50v in series makes a 100v cap I don't think they work this way. Proceed cautiously I don't know any more Mark __________________ "The geek shall inherit the earth" 2017 Burning Amp is November 12 in S.F. Thread here on diyAudio: http://www.diyaudio.com/forums/clubs...francisco.html
 14th November 2002, 07:01 PM #3 dlharmon   diyAudio Member     Join Date: Nov 2001 Location: TN, USA Equation for series caps capacitance: C = 1 / ( 1/C1 + 1/C2 +... ) so 2 40000uF 50V caps in series = 20000uF 100V Parallel caps just add. You would need to put resistors across the series caps to equalize voltage to avoid making a bomb. (Capactors have unequal leakage currents.) I would just buy caps with proper ratings. This has been done before, but mainly for things like 900V where electrolytics aren't available and high capacitance is needed. I have use this to put some 800V .56uF film caps in series / parallel to make a 1600V .56uF cap. I never build normal projects. What are you building? Darrell Harmon __________________ http://gemini.tntech.edu/~dlh5678
 14th November 2002, 07:07 PM #4 UrSv   diyAudio Member     Join Date: Jan 2002 Location: Sweden First you have to make sure that the caps are charged equally or you may exceed the voltage rating of the individual capacitor. This is obstacle number one. Second, when connecting caps in series they behave exactly the opposite of resistors that is when you connect then in series the resulting capacitance will be smaller than the largest cap. The formula for series caps is as for parallelling resistors: 1/Ctot = 1/C1 + 1/C2 ..... 1/Cn In this case you end up with half the size as they are equal and you need to invest in twice as much. Go for the correct option. Choose the right voltage and buy a size that when parellelled gives you the total capacitance needed a nd the best price/performance. Parallelling caps gives you a total of the sum of the individual caps so 4 times 10.000 uF is "the same" as 40.000 uF single cap "all other things being equal". /UrSv
 14th November 2002, 07:37 PM #5 awhiteguy diyAudio Member   Join Date: Oct 2002 Location: Oklahoma Good call Darrell and UrSv, I forgot that series caps use the same equation as parallel resistors. Shame on me... Sounds like I need to find some 100v caps. Know of any good sources? I am planning to build one of Anthony Holton's 400w symmetrical mosfet amps for some HT subwoofers. It will be my first project, so I'm sure I'll have lots of questions. There is so much good info on this forum, but sometimes it's hard to find. Thanks awhiteguy
 14th November 2002, 07:43 PM #6 dlharmon   diyAudio Member     Join Date: Nov 2001 Location: TN, USA Supplier for caps: http://www.mouser.com http://www.digikey.com Request a catalog from both or download the pdf. You can get about anything from one of the two. I think this amp may be a bit much for a first project. I think it's best to learn with a smaller cheaper amp before you smoke alot of expensive parts. (I have) I started with the pass labs zen. Darrell Harmon __________________ http://gemini.tntech.edu/~dlh5678
peranders
Electrons are yellow and more is better!
diyAudio Member

Join Date: Apr 2002
Location: Göteborg, Sweden
Re: Power Supply Capacitors

Quote:
 Originally posted by awhiteguy 2. two 50v, 40000uf cap in series for each rail Option 2 is cheaper, which is the direction I'm leaning. Are there any disadvantages to using two 50v caps in series to make a 100v cap?
To make it work properly, you must have charge equalizing resistors across the caps. This distributes the voltage.

http://www.elfa.se/elfa/produkter/se/20/2021348.htm

The resistor above fits "computer grade" caps from RIFA. They can be bought but it works perfectly with any kind.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 18 pcb's in interest.

 14th November 2002, 08:53 PM #8 dlharmon   diyAudio Member     Join Date: Nov 2001 Location: TN, USA Another idea: Use a center tapped transformer and connect the center tap to the connection between the two 50V caps. This will also maintain equal voltage. Thats how my ps works except I have the tap grounded to provide +- 35V. Darrell Harmon __________________ http://gemini.tntech.edu/~dlh5678
 14th November 2002, 09:02 PM #9 awhiteguy diyAudio Member   Join Date: Oct 2002 Location: Oklahoma I don't think I can do that if I am using the center tap as ground for +-70v. Is this correct?
dlharmon
diyAudio Member

Join Date: Nov 2001
Location: TN, USA
Quote:
 Originally posted by awhiteguy I don't think I can do that if I am using the center tap as ground for +-70v. Is this correct?
I didn't realize it was already wired that way. You would have to use 2 CT transformers, so 100V caps should be the simplest option.

Darrell Harmon
__________________
http://gemini.tntech.edu/~dlh5678

 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 Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Aussie Amplifiers         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post gehlhoff Solid State 7 12th February 2012 12:02 PM swin1 Swap Meet 0 28th October 2008 02:20 PM Vivek Solid State 59 28th February 2008 08:11 PM woody Everything Else 1 24th September 2006 06:20 PM wchick Pass Labs 12 12th August 2002 06:26 PM

 New To Site? Need Help?

All times are GMT. The time now is 11:54 PM.

 Home - Contact Us - Advertise - Rules - diyAudio Store - Sponsors - Privacy Statement - Terms of Service - Top - Opt-out policy

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki