Photoflash Caps for PSU - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 May 2003, 04:28 AM   #1
SHiFTY is offline SHiFTY  New Zealand
diyAudio Member
 
SHiFTY's Avatar
 
Join Date: Jul 2002
Location: New Zealand
Lightbulb Photoflash Caps for PSU

I just went around some local 1Hr Photo places and got 6 of the disposable cameras they throw away. Inside each is a nice alkaline battery(!) and a 160uF 330V rubycon cap.

From what I have read on usenet, (yay google) it appears they are not the best for ripple handling, so I will not be using them directly after the rectifier; but as a reservoir cap that follows the choke, I think they would be great!

I am thinking about two in series to give 80uF with a 200K resistor across each. Three of these 80uf units in parallel would give a nice 240uF which would be run at only ~460V, for a massive safety margin.

Does this sound sensible?! Saves me buying a $50 can cap.

  Reply With Quote
Old 13th May 2003, 04:42 AM   #2
diyAudio Member
 
stokessd's Avatar
 
Join Date: Nov 2002
Location: Grantham, NH
I've used them in my cheaper days after a zener string referenced pass transistor in b+ supplies with good success.

I now use caps designed for the job, now that I have more disposable income.

Sheldon
  Reply With Quote
Old 13th May 2003, 08:03 AM   #3
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Ditto Sheldon, but you have to admit the price is right!

There are some larger types available 525V/500u from Mallory IIRC, that are used in professional flash assemblies, and are quite reasonably priced. Very tough and much better sonics. If you luck across some of these grab them too. Sorry no URL (lost it in last years HDD crash) but there is an article or two on the late Doc Gizmo's site about them and they were oft recommended by Walt Jung and co in old Audio Amateur articles.
  Reply With Quote
Old 13th May 2003, 08:33 AM   #4
diyAudio Member
 
Join Date: Dec 2001
Location: Aarhus, Denmark
Cheap Photoflash capacitors:

http://www.allelectronics.com/cgi-bi...750&type=store

Jakob E.
  Reply With Quote
Old 14th May 2003, 12:21 AM   #5
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Logically, a photoflash capacitor should require low ESR, making it ideal for bypassing output stages. Conversely, it is not required to survive nearly as many charge/discharge cycles, so its ripple current capacity could be poor. I suspect that a photoflash capacitor is probably good for smoothing and occasional pulses, but not for repetitive ripple duty.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 14th May 2003, 12:43 AM   #6
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Default FLASH IN THE PAN...

Hi,

Quote:
Logically, a photoflash capacitor should require low ESR, making it ideal for bypassing output stages.
Yes, and that's all they're good for...

I use them with a stopping diode ...he,he...

Cheers,
__________________
Frank
  Reply With Quote
Old 14th May 2003, 02:03 AM   #7
SHiFTY is offline SHiFTY  New Zealand
diyAudio Member
 
SHiFTY's Avatar
 
Join Date: Jul 2002
Location: New Zealand
Well, I went and got a whole lot more throw away cameras;

I now have
7 x CM (?) 100uF 330V (rated -20*C to 55*C)
12 x Rubycon 120uF 330V
8x "Photo" 120uF 330V
2x Rubycon 160uF 330V

and a couple of miscellaneous ones with no markings. I think I will build a cap board and see how it goes. Put it well away from heat sources to keep it cool.

Oh, and these things can store a lot of energy! I shorted one out with a screwdriver and there was a massive blue spark and a good smell of ozone, I used a resistor after that!
  Reply With Quote
Old 14th May 2003, 09:02 AM   #8
dhaen is offline dhaen  Europe
diyAudio Moderator Emeritus
 
dhaen's Avatar
 
Join Date: Jun 2002
Location: U.K.
Default Coulombs..

Not too much ozone please:
Think about your location....
  Reply With Quote
Old 14th May 2003, 07:42 PM   #9
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
Quote:
Originally posted by EC8010
Logically, a photoflash capacitor should require low ESR, making it ideal for bypassing output stages. Conversely, it is not required to survive nearly as many charge/discharge cycles, so its ripple current capacity could be poor. I suspect that a photoflash capacitor is probably good for smoothing and occasional pulses, but not for repetitive ripple duty.
Actually they have quite high ESR on the order of ohms. This slows the flash pulse and lowers peak current, also preventing damage (I suppose).
They also have very low temp ratings circa 50-60C, not a very good indicator of life.

Nonetheless, of you go to PSUD and punch in 5 ohms ESR for the filter caps, it still works fine. So don't worry much about high ESR caps.

Tim
__________________
Seven Transistor Labs
Projects and Resources
  Reply With Quote
Old 14th May 2003, 08:13 PM   #10
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
In high-rel regulator designs for tube stuff, you'll often see a resistor of a few ohms in series with the output cap- Joe Curcio's power amp regulators come to mind as an example. Think of that ESR as a component-saving bonus. A few ohms of PS source resistance at very high frequencies for a tube amp is not really a terrible thing, given the current draw involved, and it can dramatically increase pass device reliability.
__________________
The more you pay for it, the less inclined you are to doubt it.- George Smiley
  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
2sc3381-GR, Rubycon 410uF photoflash, and IXYS 1kv Depletion mode MOSFETS pabbi1 Swap Meet 3 27th June 2009 03:24 AM
Replacing multi-section caps with multiple caps? Sir Trefor Tubes / Valves 1 29th May 2007 10:17 PM
Replacing ceramic disc caps with silver mica caps? G Solid State 5 18th November 2002 01:02 PM
Photoflash Caps fdegrove Parts 4 20th September 2002 08:09 PM
FILM Caps to assist Big ELYT Caps gromanswe Parts 0 9th July 2002 08:16 AM


New To Site? Need Help?

All times are GMT. The time now is 08:49 PM.


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