Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site hcrvx1.UUCP Path: utzoo!hcrvax!hcrvx1!paulb From: paulb@hcrvx1.UUCP (Paul Bonneau) Newsgroups: net.analog Subject: Re: large capacitors -- low resistance?? Message-ID: <1024@hcrvx1.UUCP> Date: Wed, 5-Dec-84 20:33:19 EST Article-I.D.: hcrvx1.1024 Posted: Wed Dec 5 20:33:19 1984 Date-Received: Thu, 6-Dec-84 00:24:23 EST References: <17@tekig5.UUCP> Organization: Human Computing Resources, Toronto Lines: 28 [Out Vile Jelly!] >> So it was with great expectation that we charged this thing up. Got a piece >> of 16 gauge wire. Taped it to a stick. Sloowly approached the terminals >> with it ... and ... nothing happened. Apparently these things have a fairly >> low internal resistance so they discharge shortly after the current is >> removed. Sigh. > Where did you learn your physics? These capacitors have a large internal >resistance. That is one of the trade-offs that had to be made in order to make >a capacitor with 3.3 F of capacity. They certainly would not be too useful >if they discharged shortly after the current was removed. The main use of these >capacitors is for such things as battery backup. They will produce a small >current for a long time, but don't try to filter the high frequency ripple >out of a power supply with them. It won't work. If you want to melt wires, >get a large computer power supply capacitor. That is what they were made >for (and you thought it was to filter power supplys). I stand corrected! My thinking on the matter was that they had a small PARALLEL resistance (ie across the plates) not a large series resistance. However I am by no means an expert on the subject (I was only making a guess). However if there was a such a beast (low resistance across the plates) the time constant would restrict its use to such things as power regulation. -- I'm a man! I'm not a horse! Paul Bonneau {decvax|ihnp4|watmath}!hcr!hcrvax