Re: Questions about current

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Mddeming-at-aol-dot-com>

Hi Peter, Matt, All, 
In a message dated 5/4/01 9:54:27 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes: 


>
> Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-uswest-dot-net> 
> " <Peter.Lawrence-at-Sun-dot-com> 


Snip 

>
> 3, you have to be careful when measuring NST outputs or you will blow your 
> meter. Terry has a good suggestion for current, put a 1kohm/25watt resistor 
> across the NST output (that's a short circuit for all practical purposes 
> since the internal res of the NST is 20k-50k) and measure the volts across 
> the resistor, 1 volt across 1kohm => 1-ma. Terry recommends a 130vac meter 
> for NSTs up to 120-ma. 


Suppose you want to measure more than just the short-circuit current. What 
would the procedure be then? 

>
> http://hot-streamer-dot-com/TeslaCoils/Misc/meter.jpg 
>
> to measure volts, make a hugh voltage divider with a long string of very 
> high 
> valued resistors (like 10 * 1MegOhm for 10:1, or 10*1MegOhm + 100KOhm for 
> 100:1, or 10*1MegOhm + 10KOhm for 1000:1). 


Since power = E^2/R, at 15kv your voltage divider would be dissipating 22.5 
watts or 2.25Watts per resistor. 1Meg 3W-5W resistors are a little pricey and 
bulky. If you multiply everything by 10, (e.g. 10 10Meg resistors and a 100K 
for 1000:1) the string would dissipate 2.25 Watts or 0.225W per resistor ---> 
1/2 watt 10Meg 5% resistors wouldn't even get warm overnight and are only a 
few cents each. 

Matt D. 
Are there a disproportionate number of coiler named Matt?