Beginner Measurements

To: tesla-at-pupman-dot-com
Subject: Beginner Measurements
From: "Jeff W. Parisse" <jparisse-at-ddlabs-dot-com>
Date: Wed, 23 Oct 1996 10:49:27 -0700
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)? Can one use measurement
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?


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