"photo" Caps & audio circuits ?

[seventenths]

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]

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]

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]

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]

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]

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]

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

 

[seventenths]

... mine are; 120mfd 350v.

Maybe I'll make a flash


7/10

 

[Juergen Knoop]

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

 

[Poindexter]

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

 

[Juergen Knoop]

I'm currently using 1000u at the amplifier board and 10000u as charging capacitor after the rectifier
regards
Juergen

 

[lineup]

I'm currently using 1000u at the amplifier board and 10000u as charging capacitor after the rectifier
regards
Juergen

might do for you

a bit too much for a simple chip amp
in my book
of course for heavy metal music we may need 20mF!!!

PS. It is NOT anything bad with high voltage rating for caps
In fact, it is good when a cap can take 200-1000 Volts
- a sign of quality. This is true for example for Polypropylene, 2.2 -10uF = input capacitors.

But for electrolytics, power Supply Caps, higher voltage means BIGGER & More Expensive.
So a waste of space and your money.


If a power Supply Cap is rated 10-20 volt above the V+ it is most cases good enough.
For a +/- 40 VDC rectifier bridge (4 diodes) supply
we can use for example 4.700uF/ 50VDC or 4.700uF 63VDC.


Regards lineup

 

[Zen Mod]

I remember ads from old periodics where Croft mentioned using photo elcos in his best models of preamps;

I have no intention to say that photo caps are better or worse than some "audio" grade ones.......but I really can't imagine worst scenario for one cap use than heavy discharging.......... charging and discharging it 100 or 120 times/sec in ordinary PSU must be piece of cake .........or easy task for them.......