Electrolytic caps?

Ok, why is "electrolytic" any worse of a term? Certainly we all know what is bing talked about.

As they're designed for hand wiring as opposed to pcb mount, I doubt many ppl would be interested in them these days.

You could always try shifting them on ebay though.

Graham

I wouldn't call that the standard method but ramping the voltage sounds like a nice idea. You still want to use a current limiting resistor though.

You also need to apply the rated voltage for some time IIRC to ensure that the oxide film is fully reformed.

As compared to the rated capacitance ?

Graham

I think the Japanese choice of calling electrolytics 'chemical caps' or chemicons makes this more obvious. Probably the least reliable components still in use but regrettably necessary.

Graham

Talking of salt messing things up....

Do you recall that GEC did a deal with Nat Semi IIRC to make a UK cmos fab back in the 70s ?

One of the lecturers at UCL had been there and taught us semiconductor physics. They could never get the process fixed. The chips would work - but 'go bad' after some months.

It was finally found that the the nichrome wire that they were using in the ovens was quenched in a salt solution during the manufacturing process. Sodium ions were 'boiling out' of the wire and entering the chips. Initially this caused no problem until the sodium ions migrated into the active region and threw the threshold voltages of the fets all over the place.

Sadly the problem was diagnosed too late and the project was dropped.

Graham

Yes, electrolytics are a cheap way to get a large capacitance and it is a trade-off between size and cost against reliability. I have to laugh at some of the people who condemn radio manufactures for using cheap paper caps 75 years ago, yet they brag about tracking down the cheapest chinese no name parts they can find for their restorations. Not all plastic insulating films are of the same quality and I wonder how long it will be before these new high voltage caps last before they start breaking down. Will people be condemning them for their bad choices in say, ten years?

On the other hand you can find NOS Sprague and other American made electrolytic caps that are fifty years old with good seals and still have the marked capacitance along with a good ESR. Not all of them, but a lot higher percentage than current production electrolytic caps will be at that age.

I read in sci.electronics.design that Pooh Bear wrote (in ) about 'Electrolytic caps?', on Mon, 28 Feb 2005:

One of the most spectacular of these trace effects is just touching a THICK tungsten wire used for the filaments of big transmitting valves with nickel-plated tweezers. Just try to bend the wire a bit and it snaps like glass rod where it was touched.

So what are they worth to someone? $1 each?

I doubt there's that many audio amps with ac coupled outputs still around these days actually.

Graham

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Oh yeah, they could be PC mounted.

Some consumer electronics used standard "FP" electrolytic caps on PC boards my drilling larger holes and using a lot of solder. They tended to get stress cracks so a modified version was made with smaller terminals and part of the tabs cut away.

I leave it to you to figure out what "FP" means! :)