Series Caps in Power supply - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 11th April 2003, 04:35 AM   #11
diyAudio Member
 
Join Date: Nov 2002
Location: New Zealand
Default Here's the info I have:

The power amp is Rod Elliotts P68 subwoofer amplifier. It delivers 300W or thereabouts into a 4 ohm load.

It is powered using a 300VA 40-0-40 Toroid to a standard 35A bridge rectifier.

The filter caps are NEW 12000uF 50V electros (Computer grade?) that are in series to give 6000uF 100V. This is per rail.

I want to add a resistor across each cap individually to balance the voltage across them.

Assuming the that 50k will be good, that's what I'll use. I don't see the point of using a smaller resistance (It'll draw more power) unless it is of particular advantage - please advise.

Thanks for the responses so far. I've mailed Rod as well to see his views on the matter.

Cheers,
Jonathan
  Reply With Quote
Old 11th April 2003, 04:41 AM   #12
Mad_K is offline Mad_K  Norway
diyAudio Member
 
Mad_K's Avatar
 
Join Date: Sep 2002
Location: Norway
The info you guys need can be found here:
http://www.evox-rifa.com/electrolyti...c_appguide.pdf
>page 4

__________________
Mads K
  Reply With Quote
Old 11th April 2003, 04:58 AM   #13
diyAudio Member
 
Join Date: Nov 2002
Location: New Zealand
Default Thanks Mad_k

Useful info.

Tells me why I haven't had any trouble yet (Worse case scenario with 20% tolerance is around 33.6V across a cap - they're rated for 50V)

Also tells me I should use 1000000/(0.015*12000) = 5k6 Ohm
resistors.

1W will easily be enough (Will only dissapate 0.15W in each resistor once everything is balanced.)

Cheers,
Jonathan
  Reply With Quote
Old 11th April 2003, 04:59 AM   #14
diyAudio Member
 
Join Date: Mar 2003
Location: Northwest
Default Re: WRONG AGAIN.

Quote:
Originally posted by fdegrove
Where did you come from with figures?

No way to calculate any values from what's given so far here, I reckon?

Why don't you reread the thread instead of contradicting yourself over and over again in a single post?
Cheers,
Look at a cap datasheet fdegrove. Most manufactures give the following forumula for their DC leakage specification:

DC Leakage = .01CV

So, we take .01 * 12000E-6 * 28v and we get 3.4ma. Your method of 100k total would allow0.56ma to flow which isn't enough to balance the caps if one has say 1ma leakage and the other 3ma. My values may have been overkill, but I'd rather be safe than sorry. I don't know the age of these caps and leakage current goes up with age.

As for the power specification, do I need to explain ohms law?

And where did I contradict myself?
  Reply With Quote
Old 11th April 2003, 07:49 AM   #15
diyAudio Member
 
Join Date: Mar 2003
Location: Northwest
Default Re: WRONG AGAIN.

Quote:
Originally posted by fdegrove
If no bleeder is present you could try a pair of 50K Rs, just make sure to use equal values and that they have ample wattage for the current you're drawing..

Quote:
Originally posted by fdegrove
Where did you come from with figures?

No way to calculate any values from what's given so far here, I reckon?
Well I reckon that P = V**2/R. So let's see... the voltage across each resistor will be 28 volts and they're 50k ohm resistors, so 28**2 = 784 divided by 50,000 = 0.016 watts which I rounded up to 0.02 watts.

So your advice to "make sure they have ample wattage" is really out of place as it's hard to buy a resistor that won't handle 0.02 watts. So please explain the "Wrong Again" part of your subject line?
  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
Powering F series amplifiers from sime power supply yoke Pass Labs 5 22nd December 2008 07:23 AM
Power supply options.. bigger trafo with less caps or medium trafo with heavy caps? rhythmdiy Chip Amps 9 23rd October 2007 01:30 AM
Series power amps using a floating power supply rtarbell Solid State 6 25th February 2006 09:18 PM
power supply: shunt or series?? AudioGeek Solid State 34 25th July 2004 03:02 AM


New To Site? Need Help?

All times are GMT. The time now is 06:45 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2