Doug Smith W9WI wrote:
Back when I was studying electronics in college in the 1970s, we were
taught that a 1-Ohm resistor and a 1-Farad capacitor would create a RC
circuit with a time constant of 1.1 seconds -- and that since it was
physically impossible to make a 1-Farad capacitor, we would never actually
see such a circuit in real life.

Of course, you can now order a 1-Farad capacitor for a few bucks from
Digi-Key. But they didn't stop there.

On page 18 of this month's RadComm (RSGB) there is a brief item about
"ultracapcitors". The devices are available in values up to 3,000 Farads.
**3,000 Farads**. Amazing.

http://www.maxwell.com/ultracapacito...l/bcap3000.asp

I believe the correct time constant for that combination is 1 second,
and has been since the '30s at least.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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"Applied Control Theory for Embedded Systems" gives you just what it says.
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