Comments on: Giant Capacitor (May, 1945) http://blog.modernmechanix.com/2006/09/05/giant-capacitor/ Yesterday's tomorrow, today. Fri, 10 Feb 2012 14:33:22 +0000 hourly 1 http://wordpress.org/?v=3.1.4 By: Thomas http://blog.modernmechanix.com/2006/09/05/giant-capacitor/comment-page-1/#comment-1063916 Thomas Fri, 26 Dec 2008 05:56:09 +0000 http://blog.modernmechanix.com/2006/09/05/giant-capacitor/#comment-1063916 The capacitance isn't big. It's small. It was small back then, too. A 2500 MMFD cap of normal working voltage (50 to 400 WVDC) will fit in the palm of your hand, and will be quite small, too, even back then. What makes that capacitor so huge is its voltage rating. The plates have to be spaced far apart due to voltage reasons (so that the voltage doesn't jump across from one plate to the other). Increasing distance decreases capacity. To bring the capacity back up, more plates have to be added. Also, since sparks jump from sharp objects better than rounded ones, all surfaces must be rounded. More metal must be added to achieve this (round tubes). Also, due to the wattages handled, the metal must be thick. Radio transmitters of the commercial variety put out hundreds to thousands of watts. All of that energy moving back and forth through that metal would heat it up if it wasn't thick enough. The capacitance isn’t big. It’s small. It was small back then, too. A 2500 MMFD cap of normal working voltage (50 to 400 WVDC) will fit in the palm of your hand, and will be quite small, too, even back then. What makes that capacitor so huge is its voltage rating. The plates have to be spaced far apart due to voltage reasons (so that the voltage doesn’t jump across from one plate to the other). Increasing distance decreases capacity. To bring the capacity back up, more plates have to be added. Also, since sparks jump from sharp objects better than rounded ones, all surfaces must be rounded. More metal must be added to achieve this (round tubes). Also, due to the wattages handled, the metal must be thick. Radio transmitters of the commercial variety put out hundreds to thousands of watts. All of that energy moving back and forth through that metal would heat it up if it wasn’t thick enough.

]]> By: Stannous http://blog.modernmechanix.com/2006/09/05/giant-capacitor/comment-page-1/#comment-10512 Stannous Wed, 06 Sep 2006 07:03:58 +0000 http://blog.modernmechanix.com/2006/09/05/giant-capacitor/#comment-10512 I tried to find a modern equivalent of this and found an interesting comparison here: http://users.tm.net/lapointe/Capacitor.htm It seems as though the 2,500 mmfd (micromicrofarads or today, picofarads) isn't that big anymore. There's a pic on that page showing 19 ceramic one of that capacity. I'm sending a link to this page to the author in hopes he will post here and explain better than I can. I tried to find a modern equivalent of this and found an interesting comparison here:
http://users.tm.net/lapointe/Capacitor.htm

It seems as though the 2,500 mmfd (micromicrofarads or today, picofarads) isn’t that big anymore. There’s a pic on that page showing 19 ceramic one of that capacity.
I’m sending a link to this page to the author in hopes he will post here and explain better than I can.

]]>