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Identify this CAP Teapo pics included.

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HyperionShrike

New Member
Can anyone identify this cap? It was glued down and it just so happens right over the uf. On my ESR it's value is 115uf but if you look carefully you can see a 22 just before the glue.
 

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kinarfi

Well-Known Member
What type on ohm meter do you have, mine has a capacitance meter in it, but on larger caps, I have to measure the time it takes to go OL (out of limit). Short the known 220uf and measure it's resistance and the time it takes to OL or infinite, now repeat on your unknown.
kinarfi
 

BrownOut

Banned
I recommend you replace your cap with the same voltage rating. Electrolyitcs like to be operated close to their rated voltage.
 
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Nigel Goodwin

Super Moderator
Most Helpful Member
I recommend you replace your cap with the same voltage rating. Electrolyitcs like to be operated close to their rated voltage.

I would disagree entirely, higher voltage gives lower ESR - and there's no advantage (but plenty of disadvantage) operating electrolytics near their rated voltage.
 

BrownOut

Banned
I stand by me recommendation. It's not good to operate an electrolytic much higher than it's rated voltage. That does not apply to other types of caps.
 
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BrownOut

Banned
A converse is not a negative. This is a widely documented design recommendation. If you want to do this ( not recomended ) the following procedure should be used: Connected the capacitor to a power supply set to 80-90% of its rated voltage. Use a 30K series resistor to limit current. Operate the power supply for 5 minutes. Then you can disconnect the cap and install it.

There are othe opinions on the subject. This is mine.
 
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Nigel Goodwin

Super Moderator
Most Helpful Member
A converse is not a negative. This is a widely documented design recommendation. If you want to do this ( not recomended ) the following procedure should be used: Connected the capacitor to a power supply set to 80-90% of its rated voltage. Use a 30K series resistor to limit current. Operate the power supply for 5 minutes. Then you can disconnect the cap and install it.

I'm sorry, what on earth are you on about? - you're been very unclear - and this seems to have no relation to your assertion that you should use electrolytics at near to their maximum voltage?.
 

hdc090360

Member
Working Voltage

For over thirty years I have worked on the assumption that the working voltage of a cap is a maximum and that you could always go up but never down.

As things do change, I decided to do some research into what the manufacturers say, to make sure I am still doing the right thing.

I checked the websites of four manufacturers, Elna, Rubycon, NIC and Teapo. Reading through the cautionary notes from all of these, there is nothing about the working voltage except to say do not exceed it.

Brownout, you say this is well documented. Can you point me in the right direction to find this documentation?
 

BrownOut

Banned
For over thirty years I have worked on the assumption that the working voltage of a cap is a maximum and that you could always go up but never down.

As things do change, I decided to do some research into what the manufacturers say, to make sure I am still doing the right thing.

I checked the websites of four manufacturers, Elna, Rubycon, NIC and Teapo. Reading through the cautionary notes from all of these, there is nothing about the working voltage except to say do not exceed it.

Brownout, you say this is well documented. Can you point me in the right direction to find this documentation?

Electrolytics should not be used if the DC potential is well below the capacitor working voltage. -ARRL Handbook for Radio Amatures. Chapter 10

When I was a young engineer, I worked for a company that was a global leader in amplifier design. We were forbidden by engineering department rules from specifying an electrolytic capacitor where the operating voltage is less than 75% of the caps rated voltage. The author of the design rules was a 30 year veteran of amplifier design, so I believe he knew what he was talking about. Some of the cap manufactures recommend at least 70% operating voltage.

Another thing that was forbidden was "making" a non-polarized capacitor by connecting two electrolytics back to back. Once, I was discussing a requirement for a large, nonpolarized capacitor with the company's lead engineer. He told me that it was never recommended. Then, in confidence, he told me if I am ever in a situation where I have to do this, I should first condition the capacitor by a method similar to the one I wrote about above. Of course, he wasn't telling me I could break company rules, which led to to believe some of the engineers were moonlighting :)

I've always followed these guidelines although I don't work for the company anymore. But, if I'm just fooling around on the bench and don't care about long term stability and such, sure, I'll throw in an arbitrary cap off my bench, just to keep things moving.
 
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Mr RB

Well-Known Member
Modern caps use much better electrolytes than the caps from 30-40 years ago. They don't need the higher voltages to get good plate charge formation and they almost never need "conditioning" any more. Both those concepts are pretty outdated.
 

Boncuk

New Member
Operate the power supply for 5 minutes. Then you can disconnect the cap and install it.

There are othe opinions on the subject. This is mine.

I strongly recommend to discharge the cap before installing it. :D
 
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