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Re: Beginner Measurements

Tesla List wrote:
> 
> Quick and Dirty resonance check
> 
> >From jparisse-at-ddlabs-dot-comWed Oct 23 21:37:51 1996
> Date: Wed, 23 Oct 1996 10:49:27 -0700
> From: "Jeff W. Parisse" <jparisse-at-ddlabs-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Beginner Measurements
> 
> All,
> 
> I just started using a tip from Richard Hull to measure the resonant
> freqs of our tesla coils and I feel as if I've discovered the "next
> level" (a self realization... I know you guys already know this stuff).
> I'll repost the tip at the bottom of my post...
> 
> My questions are... Now hungry for more actual readings (instead of
> computer projections or forumlae) I want to know if there is a way to
> measure primary resonance with a VOM, Frequency Counter and Frequency
> Generator (old Heathkit 1Hz - 1MHz, 10V)? 


Yes, Gary Petersen had a nice article in the TCBA news some ten years 
ago, can't remember the issue, on primary measurement.  But why do it?  
Who cares!  What ever you find will definitely be incorrect! 
 

I find the resonant frequency of my loaded resonator,...in place.  Next I 
use the standard frequency equation for caps and inductors solved for L= 
( .0253/(Freq squared X tank capacitance) ) This gives me the theoretical 
tap inductance on the primary.  I now use an inductance meter to locate 
that point on the primary and then just ingore it and grab one extra full 
turn!  Fire it up....  Move tap to max spark from there.  Usually optimum 
tune is found to be from 1/2 turn to 1.5 turns more than the theoretical, 
calculated tune point.  This ultimately depends loading and geometry.

Richard Hull, TCBOR


>Are there techniques to pinpoint the tap point? Is ther a way to measure the mH of
> a particular primary coil. Since inductance increases as one moves a tap
> along the primary and the resistance of the primary conductor increases
> too, wouldn't it be possible to somehow relate the two in an effort to
> measure resistance to infer inductance?


Nope!  No way possible.   They are not even slightly related to one 
another. R. Hull

> 
> Jeff W. Parisse
> www.ddlabs-dot-com/tesla/
> 
> PS Thanks Richard...
> 
> Subject: Quick and Dirty resonance check
> 
> All,
> 
> We have used a really trick, used for years here from finding resonant
> frequencies.  No scope or meter required. You need only a good frequency
> generator.  We prefer the old clunky ten ton vacuum tube Hewlet
> Packard units of the 50's and 60's with 50 ohm output impedances.
> 
> Buy two real good (expensive) radio shack ultra bright red LEDs.  Hook
> them in parallel, but reversed anode to cathode.  put the pair in
> series with the hot line of the generator and hook to the base of the
> coil under test. (ground the generator's negative or common lead)  I use
> a full 5 volt RMS output signal from my generator.  Tune the generator
> until the leds are at their brightest and then read the dial. (assumes
> dial is fairly well calibrated.)  This is just tuning until max base
> current flows (resonance)
> 
> Note!  A modern 600 ohm generator can be used with reduced brightness.
> A single LED will also work.  The key to success is a healthy voltage
> output from your generator and ultra efficient LEDs.
> 
> Therefore, the first major hunka' test gear for the coiler after a good
> meter is a good signal gen.  A scope should be way down on the buying
> list for a beginner.
> 
> Richard Hull, TCBOR