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Old 21st Nov 2019, 2:11 pm   #16
cmjones01
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Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
Default Re: Sun Microcomputer II Motortester 1215

Quote:
Originally Posted by Zelandeth View Post
I'm assuming as there's nothing fundamentally wrong with tantalum caps...they're just operating a fair way outside their anticipated lifespan at this point in time. Is that correct or is there a modern better suited capacitor technology out there?
Tantalum bead capacitors have been dismally unreliable forever, and they still are. They have a large capacitance in a small case size, and excellent equivalent series resistance, so they were popular for decoupling applications. However, they're very sensitive to pulses of even minor overvoltage or heavy current, so they have an annoying tendency to go short-circuit when connected across power supplies. Which is how most of them are used. Having been bitten by failures too many times, I've long since given up designing them in to new circuits unless absolutely necessary.

Fortunately, aluminium electrolytics have come on in leaps and bounds since the 1970s, and a good quality modern electrolytic (I specify Panasonic FC series out of habit, but plenty of others are available) will almost always substitute for an old Tantalum bead.

Chris
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