"photo" Caps & audio circuits ?

seventenths · 3rd June 2007, 06:49 PM

Hi all,
While working on a GC and digging thru my rapidly growing parts, bin I found a couple of caps that are labeled "photo". These are 120mfd @ 330V.
Are these useful in audio circuits?
TIA

7/10

Conrad Hoffman · 3rd June 2007, 08:18 PM

Photoflash caps are designed for high discharge rates, and I've seen admonishments not to use them for regular cap service. I don't know why not, as they seem to perform the same as a conventional cap of the same value and voltage. Anybody know of a reason to avoid them?

FastEddy · 3rd June 2007, 09:40 PM

An example: http://www.capacitorindustries.com/web/CD17S.htm ... note that these "photo flash" types are special purpose electrolytic capacitors and may be of only slight value for DIY audio ... but experimentation may be in order.

seventenths · 3rd June 2007, 10:00 PM

Conrad & F-Eddy,
Thanks for the replies...
In an effort to keep moving forward, I've left a terminal strip in the PSU section to facilitate easy CAP experimentation. I will

er-uhhhh ...test them

Onward,

7/10

Poindexter · 4th June 2007, 04:50 PM

Seven, what I've heard is that in normal service photoflash caps are charged all the way up, then completely discharged; this once a minute or so, episodically. They are designed and constructed uniquely for this odd sort of service. Put in a power supply, where they are charged most of the way up and then partially discharged and recharged sixty times a second, their service life will be very short.

If you're looking for very good, very economical electrolytic caps, have a look at Panasonic ED, TSHA, TSHB at Digi-Key. I have found nothing better, and I have A-B'd them with the heavy hitters.

Aloha

Poinz

seventenths · 4th June 2007, 05:53 PM

Mahalo P-Dexter,
Seeing your location makes me think I should fly out for a personal A-B test

I'll follow your advice on my next order... I have a handful of chips and a Big trafo, but still need to decide on a project. Hmmmmmm

Aloha
7/10

Juergen Knoop · 4th June 2007, 06:00 PM

hm, I find the values to small to be useful in a chipamp design

seventenths · 4th June 2007, 06:24 PM

... mine are; 120mfd 350v.

Maybe I'll make a flash

7/10

Juergen Knoop · 4th June 2007, 06:36 PM

yes, with 120uF/350V you can't do much exept flashes

Poindexter · 4th June 2007, 06:41 PM

Juergen,

How big are you guys using? The original schems I've seen are calling for about 1KuF as the last tank, which looks pretty small to me. 18v into an 8 ohm load is 3 amps, which is going to drain a thousand mic cap pretty quickly.

Aloha,

Poinz

3rd June 2007, 06:49 PM	#1
seventenths diyAudio Member Join Date: Apr 2007	"photo" Caps & audio circuits ? Hi all, While working on a GC and digging thru my rapidly growing parts, bin I found a couple of caps that are labeled "photo". These are 120mfd @ 330V. Are these useful in audio circuits? TIA 7/10

3rd June 2007, 09:40 PM	#3
FastEddy diyAudio Member Join Date: Jun 2006 Location: North Californie	An example: http://www.capacitorindustries.com/web/CD17S.htm ... note that these "photo flash" types are special purpose electrolytic capacitors and may be of only slight value for DIY audio ... but experimentation may be in order. __________________ Over compression is a problem with modern CD recordings

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3rd June 2007, 08:18 PM	#2
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	Photoflash caps are designed for high discharge rates, and I've seen admonishments not to use them for regular cap service. I don't know why not, as they seem to perform the same as a conventional cap of the same value and voltage. Anybody know of a reason to avoid them?

3rd June 2007, 10:00 PM	#4
seventenths diyAudio Member Join Date: Apr 2007	Conrad & F-Eddy, Thanks for the replies... In an effort to keep moving forward, I've left a terminal strip in the PSU section to facilitate easy CAP experimentation. I will er-uhhhh ...test them Onward, 7/10

4th June 2007, 04:50 PM	#5
Poindexter diyAudio Member Join Date: Oct 2004 Location: Maui, Hawai'i, USA	Seven, what I've heard is that in normal service photoflash caps are charged all the way up, then completely discharged; this once a minute or so, episodically. They are designed and constructed uniquely for this odd sort of service. Put in a power supply, where they are charged most of the way up and then partially discharged and recharged sixty times a second, their service life will be very short. If you're looking for very good, very economical electrolytic caps, have a look at Panasonic ED, TSHA, TSHB at Digi-Key. I have found nothing better, and I have A-B'd them with the heavy hitters. Aloha Poinz

4th June 2007, 05:53 PM	#6
seventenths diyAudio Member Join Date: Apr 2007	Mahalo P-Dexter, Seeing your location makes me think I should fly out for a personal A-B test I'll follow your advice on my next order... I have a handful of chips and a Big trafo, but still need to decide on a project. Hmmmmmm Aloha 7/10

4th June 2007, 06:00 PM	#7
Juergen Knoop diyAudio Member Join Date: Jan 2007 Blog Entries: 3	hm, I find the values to small to be useful in a chipamp design

4th June 2007, 06:24 PM	#8
seventenths diyAudio Member Join Date: Apr 2007	... mine are; 120mfd 350v. Maybe I'll make a flash 7/10

4th June 2007, 06:36 PM	#9
Juergen Knoop diyAudio Member Join Date: Jan 2007 Blog Entries: 3	yes, with 120uF/350V you can't do much exept flashes

4th June 2007, 06:41 PM	#10
Poindexter diyAudio Member Join Date: Oct 2004 Location: Maui, Hawai'i, USA	Juergen, How big are you guys using? The original schems I've seen are calling for about 1KuF as the last tank, which looks pretty small to me. 18v into an 8 ohm load is 3 amps, which is going to drain a thousand mic cap pretty quickly. Aloha, Poinz