Re: Measuring resonance with a scope

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

Original poster: "Charles Hobson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <charles.a.hobson-at-btinternet-dot-com>



> Original poster: "Reverend K Kanno by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <presence-at-churchofinformationwarfare-dot-org>
>
> On Thu, 5 Jul 2001, Tesla list wrote:
>
> > Original poster: "Jason Petrou by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>
> >
> > Andrew,
> >
> > Yup I found out how to do this... Look at chuck's site
> > http://www.charles.a.hobson.btinternet.co.uk/MEASUREMENTS.htm
> > and you can
> > see how to do it. Not having a frequency counter i am a bit lost
though...
>
> Hmm. Not sure why you even need a frequency counter. You can measure
frequency
> with any scope. That is why they have sweep ranges and a grid on the CRT.

Hi Jason,

The important thing is to get both primary and secondary circuits
independently  tuned closely to the same frequency. So matching frequencies
becomes the name of the game. As indicated  by Rev. Kanno above, this is
easily achieved with a modern oscilloscope. With careful time base
measurements and using the  simple f = 1/T where T is the period of one
cycle, you are off and running without a frequency counter.

On the other hand, with the neat circuit by Terry referred to in another
post on this subject, you may even get by without an oscilloscope. Your
initial calculations for resonant frequency using L and C values will put
you in the ball park on the TC operating frequency. Then using the free
running multibrator (MV) and LED combo connected to the secondary coil  you
can vary  frequency  to get  the LED indication as described and carefully
note the variable resistor (frequency control) position. Then and tune the
primary circuit to this same variable resistor setting.  What I really don't
know is what  errors can be tolerated in Tesla coils as I have been spoiled
with the frequency counter. The MV will drift in frequency with temperature*.

Have fun,  Chuck

*I used temperature a stable poly timing cap.  The drift is nil ;-) - Terry