[Home][2017 Index] [TCML] Fw: Tesla Digest, Vol 112, Issue 3 [Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[TCML] Fw: Tesla Digest, Vol 112, Issue 3

Anyone know where we can simply buy a bar of this stuff, lol.  Sure we can buy replacement brushes. But information on how to make or obtain the raw material; this magic carbon based ceramic is non existent. Probably because it's stupid easy and the brush manufacturers keep a tight lid on it.Surely someone has a pile of magic brush material hidden somewhere...Or an ancient paper describing its design...
------ Original message------From: Greg Leyh Date: Tue, Feb 21, 2017 11:10 PMTo: tesla@xxxxxxxxxx;Cc: Subject:Re: [TCML] Tesla Digest, Vol 112, Issue 3
Hi Bert,That's a cool bit of info... Did not know that the anisotropic nature of brushes was so pronounced, and that it's exploited in variacs to reduce turn-turn shorts!Thanks,GregOn 2/21/2017 6:38 AM, tesla-request@xxxxxxxxxx wrote:> Date: Fri, 10 Feb 2017 11:09:53 -0600> From: Bert Hickman> To: Tesla Coil Mailing List> Subject: Re: [TCML] Repair parts for variable transformers?> Message-ID:> > Content-Type: text/plain; charset=UTF-8; format=flowed>> Hi Paul,>> "Variac" brushes are made using anisotropic (grain-oriented graphite)> material. The electrical conductivity between stacked graphite crystal> planes is markedly higher than the resistance parallel to the crystal> planes. Brush manufacturers typically formulate a mixture of carbon and> oriented carbon-graphite that provides sufficient mechanical strength> while still maintaining a relatively high ratio of conductivity (~10:1)> between axes.>> A Variac brush is oriented so that the high-resistance axis is across> the "thin" dimension as the brush makes contact with the winding. This> reduces turn-to-turn short circuit current when the brush bridges a> couple of turns. Also, the main body of the brush "averages" the output> voltage between turns, smoothly and continuously varying the output as> the brush transitions from one turn to the next. Using a standard carbon> brush may cause overheating of the brush tips, arcing, and excessive> wear of the brushes and winding.>> Following is a possible source for the proper material - you may need to> find a similar-size brush and then trim it to fit your unit.>> http://www.carbonbrush.com/variacbrush.htm>> Good luck,>> Bert_______________________________________________Tesla mailing listTesla@pupman.comhttp://www.pupman.com/mailman/listinfo/tesla
Tesla mailing list