RE: Oscilloscope's

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

Scopes are great tools, but it's important to understand just where they
are and are not useful.

First, resonant rise IS a continuous process.  Tube and MOSFET CW coils
make use of this process, but spark gap coils do not.  A scope is useful
for finding the resonant peak of a secondary coil excited by a sine wave
generator (or Terry's Tesla Coil Tuner), again using the principal of
resonant rise, but since it's a continuous waveform, any scope is
equally useful.

I've never heard of using a scope for PFC matching.  With a static gap,
the primary (actually ALL) waveforms are so chaotic that only a VERY
long term (like 10 seconds or more) averaging yields any useful
information about mains currents, and a scope is useless here.  And with
a sync RSG, the primary currents are stable, so any sort of AC current
meter will tell you where you stand.

I suppose a scope could be used to measure inductance with the aid of a
signal generator and known capacitors, but any kind of scope is equally
applicable, and there are better ways to do this.

Short of building the fiber optic probe electronics to allow direct
connections and measurements to one's coil, the most useful application
of a scope is to observe secondary quenching by simply having the probe
near the operating coil.  Here the waveform is repeatable enough that a
storage scope is not required.

If I had only a modest chunk of cash to invest in test equipment, a
scope would not be high on the priority list.  More useful would be a
capacitance/inductance meter (Wavetek 27XT,
http://www.metermantesttools-dot-com/products/xtseries.asp  for ~$100),
which also has a built-in frequency counter (hook it up to a TCT, not
your coil), and then build Terry's Tesla Coil Tuner:
http://hot-streamer-dot-com/TeslaCoils/Misc/TCT/TCT.htm

Regards, Gary Lau
MA, USA

>Original poster: "Jason by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jasonp-at-btinternet-dot-com>
>
>Jason,
>
>The TDS 200 series scoped by Tektronix are generally considered to be
the
>best trype of scope for TC use. The reason that they are good is
because
>they can sample an event (like resonant rise) rather than just display
a
>continuous waveform. Continuous real time scopes can be useful for PFC
>matching etc. but for things like measuring current spikes, resonant
rise
>and inductance the TDS scopes are the best.
>
>Unfortunately you get spiked when it comes to the price. A nre TDS220
scope
>costs 1200 quid, with a calibration certificate. This does not include
>probes or any add on modules, just the scope and the power lead :) I
have
>been trying to find one of these babies for about a year now, and let
me
>tell you that they are very hard to find secondhand.
>
>Good luck,
>Jason
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Sunday, September 30, 2001 4:07 PM
>Subject: Oscilloscope's
>
>
>> Original poster: "jason wallace by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jcwallace-at-cybrtown-dot-com>
>>
>> hi everyone,
>> this is just a simple question what would be the best oscilloscope to
get
>>to
>> measure tesla coils overall
>> thanks jason