Re: Beginner Measurements

To: tesla-at-pupman-dot-com
Subject: Re: Beginner Measurements
From: open_minded <bturner-at-apc-dot-net>
Date: Thu, 24 Oct 1996 01:40:55 -0700
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)? 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...
> 


Jeff -

  What you do is remove the secondary from the magnetic influence of
the primary coil. Next, short your spark gap with a short jumper lead.
Connect your signal generator across either the capacitor(s) or the
primary coil and with a small (600 ohm to 1K) resistor in series with
the 'hot' lead from the signal generator.

  If your VOM is sensitive enough and accurate at the frequency in use,
you will see a voltage peak at the resonant point of your primary tank
circuit. (The primary components form a *parallel* resonant tank. In
such a circuit, voltage will peak at resonance as current minimizes. In
the secondary, which is for practical purposes is a series-resonant
circuit, the reverse happens, and it will *pull* current, thus lighting
the LED's (ala Richard Hull).

  Find the peak and use your counter to get the numbers.

- Brent