Re: Neutral Spike Re: [EVGRAY] Vehicle audio - Wikipedia

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OleI notice that Zilano likes to use Varistors in her circuits to keep the voltages down. You see them in her circuit sketch drawings.
Cheers Warren
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  On Mon, 26 Nov 2018 at 8:53 PM, [email protected] [EVGRAY]<[email protected]> wrote:       
Hi Mick,

TVS diodes are rated for some max power dissipation and perhaps some max energy too (fusing energy I^2t). If applying more energy than the max i^2t rating it melts. As being fast Zener diodes they clamp the voltage at some level while having current through them at the same time which means power dissipation in them. If reading EMC (EMI) theory several stages are needed to protect for powerful EMP transients. The first step is a spark gap. The spark gap is followed by a varistor that is followed by a TVS or Zener diode. The spark gap breaks down to low impedance which reflects or dissipates much of the energy of the signal. The varistor is a solid state spark in some metal grains and has the same purpose as the spark gap. the TVS or Zener diode stage removes the rest of the energy to protect the sensitive electronics. It is essential to know how the electromagnetic radiation is transferred between the different stages to prevent it from reaching the sensitive electronics. Every current loop transmits the energy as a very penetrating magnetic field. That magnetic energy has to be dissipated or reflected which can be done with electrical conductive materials like iron or aluminum. The field induces current in the screening material which requires only connecting the circuit inside the screen to a single point. Audio guys probably have experienced this when building amplifiers.

A thyristor (SCR) crowbar is also a good protection. It shorts the pulse just like a spark gap and then blows a fuse to disconnect the circuit to be protected..

Regards
Ole



---In [email protected], <mkjekyll@...> wrote :


Hi Norm, 


This paper is one of your excellent references.


I would like to replicate the events through the plasma that Iachieved as it creates a huge magnetic pulse that can be harvestedbut as you say gets to kill the solid state stuff as if the TVSdiodes were not even there. At least the ferroresonantamplification without the plasma gap just cooks the TVS diodeslike popcorn even though rated at 1000 amps with only about 2 amp23v input, but spared the rest, I guess it chose at the diodes tomanifest.  Oh yeah the ferrotranny was connected with 30 guagewire wrap wire when the 1000 amps TVS diodes exploded from 46w andwire was fine. Have not built the tube circuits yet just workingon the solid state grid control circuits first then plan todecouple with something similar to cascode so hopefully thesuperfast gate driver does not cook.  


Not sure if Ole's snubber network would stop the event but havethe feeling so since caps will suppress the rise time and killringing, but have not tried so can't say.  Seems to me the eventis created right at the switch and the rise in voltage is like theinertia x acceleration before the end of a whip cracks andnecessary.  





"Why does death need time?  Death needs time for what it kills togrow in."




On 11/26/2018 4:44 AM, Norman Wootannwootan@... [EVGRAY] wrote:


 


Precisely, Bob Paddock.  Please read this document tounderstand that a local plasma event must occur (Arc inthe gap) for the manifestation of this energy. Pleaseread:  http://www-brs.ub.ruhr-uni-bochum.de/netahtml/HSS/Diss/TassiEmanuele/diss.pdf

On 11/25/2018 7:36 PM, BobPaddock bob.paddock@...[EVGRAY] wrote:

 
> Why not replace the relay with a switchingtransistor. Mechanical switches wear fast compared toa semiconductor switch.

What if the Arc/Spark is part of the actual process ingetting more energy?

Every O/U thing I've ever though worked usually had aPlasm or Arc/Spark.
Usually not intentionally and the designer alwayswanted to get rid of it.




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