Capacitor ID

[pontiacpete]

Hi,
Wondering if someone could help me out here. I found a shorted tantalum cap with 100-20 written on it. My guess is that it's a 100uf 20v cap. If that's correct can I use the equivalent value in an electrolytic capacitor in its place?

Thanks
pete

[Leo_Gnardo]

I don't see why not. Tants were cheap and popular in the 70's, now not so much. Double check & make sure the voltage in the circuit is what you think it is, 20V or below. These days caps usually have voltage ratings 25V, 35V, 50V, any will do fine.

[pontiacpete]

Thanks Leo!
This amp is a Kustom 200A. The same cap on the other channel is seeing 20v. Pretty much at its limit. I guess I will up the voltage of that cap.

Thanks again
pete

[Leo_Gnardo]

Sure, if the other cap is right at its limit may as well replace it too right now, cheap insurance.

Kustoms were loaded with tantalum. They couldn't afford to build that amp these days with those caps, they've gone out of sight.

[52 Bill]

Cost of Tantalum like a lot of things has gone sky high.

My recollection is that back in the '70s tantalum caps were more expensive than run of the mill aluminum lytics. They were touted to be state of the art high reliability parts, but that proved to be not so much true.

[Mick Bailey]

Child: "Mummy, where does Tantalum come from?"
Mother: "Out of Mummy's tummy"
Child: "So it doesn't come from Coltan, often mined by poor exploited black people with their bare hands?"
Mother: "Of course not, dear. If that was the case the products that use Tantalum would be ethically reprehensible and we wouldn't buy them".
Child:"Oh, that's OK then"
Mother: "Sleep tight".

[xtian]

100uF? Doubt it! Numerals without any qualifier is usually pico Farads, so, 100p.

[rjb]

100uF? Doubt it! Numerals without any qualifier is usually pico Farads, so, 100p.

Not for tants. Lowest value made is 1nF (1000pF).
Tantalum Capacitor » Capacitor Guide

Tantalum capacitors are made with capacitance values ranging from 1nF all the way to 72mF and they are much smaller in size than aluminum electrolytic capacitors of the same capacitance.

What is a tantalum capacitor, AVX, Vishay tantalum capacitors - Future Electronics

The most common values for capacitance are 10 µF, 22 µF, 47 µF and 100 µF. We also carry tantalum capacitors with capacitance up to 6000 µF.

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...If that was the case the products that use Tantalum would be ethically reprehensible and we wouldn't buy them".

I've heard that rhino horn makes an excellent dielectric.

-rb

[Leo_Gnardo]

100uF? Doubt it! Numerals without any qualifier is usually pico Farads, so, 100p.

Some late 70's gear I worked on, some I still own, loaded with tantalums, generally bulbous looking things looking like engorged ticks. All in microfarads, generally 1 thru 220, most bright orange but plenty in other kandy kolors. It was about that time some audio experts determined they were OK for filtering, not so much for passing audio signals. In spite of that I used a Kelsey mix console crammed with tantalum for thousands of shows, and even got some excellent board recordings in spite of the vaunted "tantalum distortion." If you can find some old issues of Audio Amateur, there's some good articles on the audio qualities of various capacitors. And as has been noted, it may have a lot to do with how the caps are biased, or not biased. Or maybe my ears are just bad.

Tantalum is a fantastic metal with unusual properties, worth your time having a read on wikipedia.

[Enzo]

Tantalum caps are great in some applications. Unfortunately they have zero tolerance for reverse voltage or over voltage. Easy to kill them.

Regular lytics are quite compact these days, I never buy tants for replacements.

[Tom Phillips]

There are discussions about refurbishing 4XX series Tektronix scopes which used a lot of tantalum caps. The recommendation, if replacing the tantalums with new tantalums, was to make sure that the new part was rated for at least 2X the actual working voltage of the circuit location. This isn't required for all the caps. There were just some of them that were operating close to their voltage rating.

[g1]

Tantalum Capacitor » Capacitor Guide

Tantalum capacitors are made with capacitance values ranging from 1nF all the way to 72mF and they are much smaller in size than aluminum electrolytic capacitors of the same capacitance.

I had to see how big that 72,000uF tantalum was. It's only 25V but about 1.5 inch diameter and a bit more than 1/2 inch tall.

[xtian]

Thx for the education!

[rjb]

I had to see how big that 72,000uF tantalum was.

P-shaw, that's nothin'.
I bet this 100 farad, 1.3 kilo-buck cap is made with rhino horn.
CPCC2 - 100 Farad Competition Capacitor - 16 Volt | Rockford Fosgate®

-rb

EDIT:
Found this. I guess this is how they really work.
http://www.arborsci.com/Data_Sheets/P6-8012_DS.pdf

[g1]

P-shaw, that's nothin'.
I bet this 100 farad, 1.3 kilo-buck cap is made with rhino horn.

Ok, it's not a single cap, you had me going there.
I've only seen as large as the 1F in the pdf. They started showing up in the 90's in Dat's and video cams to unload the tape from the mechanism if there was a power outage. Only 5V though.