Original poster: Terrell Fritz <terrellfone@xxxxxxxxxxxxxxxxxxxxxxx> ***************************************************************************************I'm adding this MODERATER NOTE: What you say Terry is very good and comes from the heart. Everyone should read this. Hopefully we all can do our part in reinforcing the safety side of our hobby.
************************************ Terry's post follows ****************************
Hi Mike,Thanks for saying it "calmly", as opposed to my "berserk" response... >:o) I have grown VERY "tired" of MMC safety resistors being "flippantly discounted" by those that "don't know"... Early on, "we" all realized that shocks from MMCs were a "serious problem"... The work into the solution and use of the bleeder resistors was " no accident" or "whim" safety thing...
"I" worked "so darn hard" on MMC's.... We early experimenters with MMCs got shocked early on by MMCs "all the time" and realized that having ?50 caps? instead of ?just one? simply magnified that chance of getting shocked ?50 times over?... Thus, the ?bleeder resistors? were introduced as the simple cheap solution, and MMCs charged ahead... I hear posts ?today? of people not using the resistors and there stories of getting shocked... That is ?not new? and was ?well known? from ?day one?... ?I tried? to warn.... I pray no one ever gets killed... But that is a ?very real? possibility "now"...
I "tried so hard" to promote the use of safety resistors... I still mail the resistors away "free" to any who wishes them... An MMC is much like a "cluster bomb" without safety resistors... Almost all of the early developers of the MMC realized far too well of the danger... 50 caps just amplifies the dangers 50 times over...
?I? can't ?fix it?... In this case, I cannot fire anyone, recall products, issue customer alerts, call on corporate lawyers for help, I can't even ?fly out there?... I can't even call end user's safety engineers to start the similar safety processes on ?their end? for taking safety defective units out of their production service and return them for safety modifications... Unlike my duties in the corporate world, ?I? am powerless ?here?...
I was "DEEPLY" disturbed that "commercial" Tesla coil's were going "into the field" without safety resistors on the MMCs... I fear that will be "our Bhopal"...
As far as corona discharge making an MMC safe... I have to call that "simply ludicrous"... Charge an MMC without resistors up to full voltage and come back a few days later and "test" (safely) what charge is left on it... It is a simple field stress thing... It is all "simple" physics... Poly caps "just don't discharge by themselves"...
?I? am ?very worried? now... The newer designs are FAR more dangerous than we are "used to"... In the ?good old days?, new coilers were lucky to get a ½ inch spark before it all burnt out... Today you can ?just buy? a ?powerful? Tesla coil... Most of the good ol' Tesla coils off say E-bay or Information Unlimited are pretty conventional and pretty goofed up... However, that is changing....
So I am now very worried that systems like PIRANHA will be ?misused?... If you can't manage to wire up a 0.5 cent safety resistor, you can't be trusted to wire up a system like PIRANHA... Let alone sell it to ?third parties? as ?customer product?...
I don't know what to do from now on... The technology is there, but the "wisdom" is certainly not...
I "pulled" the PIRANHA site off line... It is a cool technology, but one that can be "exploited" at the risk of death if careless persons "sell" it...
Most of the people who are working on these system are ?cool? , but contact me off-list directly for questions now... I am super happy to help you get your's going... But I am afraid the technologies are not safe for the ?public?... And, I am afraid that there are those that will misuse it for the sake of greed, rather than safety.
I must ?sincerely ask?, when offering ?advice? to ?newbies?, side "far strongly" on ?safety?!!! They really don't ?know better?... PIRANHA-III will now "never" be released to the "public"...
Terry At 09:54 PM 2/20/2007, you wrote:
Original poster: Mike <megavolts61@xxxxxxxxx> DC,I'm not arguing with you on the coils you build and sell, but there are a lot of guys on this list who use MOT's with voltage doubling circuitry, which would keep the charge on the capactior if turned off durning the charging cycle of the cap. The diodes would prevent the charge from bleeding off therefore the bleeder resistors are a MUST. Therefore, for safety of new coilers, you should advocate the use of them rather than argue against their use.My $0.02, Mike The two paths from the nst to it's center-tapped ground, the winding resistance is perhaps 10K at maximum. Using a 5RC time constant the reduces the cap discharge time to under 10 seconds for most small and medium nsts with their respective small cap bank values. Perhaps this is why our coils have never shocked anyone. We always run on AC and never DC. Also, at higher potentials, the small dia of the cap leads and any single sharp point on the cap bank board will bleed off charge as corona in much the same manner as a high potential Van de Graaff generator, even with it's symmetrical well-rounded terminal, will bleed off over 400 kV into the ambient air, without being discharged with a ground wand, in under 60 seconds. The MMC caps are at much lower potential but with their nst resistance path directly to ground and any slightly sharp point on the cap board or connections dangerous potentials are quickly bled off. Dr. Resonance