Re: actual measurements & pictures of the TC in action
Subject: Re: actual measurements & pictures of the TC in action
From: Terry Fritz <twftesla-at-uswest-dot-net>
Date: Fri, 06 Aug 1999 11:47:34 -0600
Some of these measurements need special or sensitive equipment to make and
are beyond the meter's ability to measure.
Primary Inductance - This inductance is usually so small that it falls at
the edge of most simple meter ranges. The best way to measure Lp is to use
an oscilloscope, sine wave generator, and frequency counter. A known
capacitance is placed across the primary (like the primary cap) and the
resonant frequency is found and the values are back calculated from there.
This method can easily get the correct value to less than 1% error.
Primary Wiring - a piece of wire has inductance and capacitance. However
these values are far below what you meter can measure. The capacitance is
on the order of 1pF and the inductance may be around 50nH. These values
are usually so small than can be ignored.
Secondary Inductance - Your meter should be able to easily and accurately
Cself - Cself needs to be measured with the scope, signal generator, and
counter setup mentioned above. It is very sensitive to the surrounding
objects and is known to be tricky to measure accurately.
Ctoroid - Like Cself, it needs the special equipment but the measurement is
far more stable and easy to do accurately.
Csparkgap - Your meter probably can measure this just fine.
Cnst sec-gnd - Your meter can measure this.
Rnst - secondary - Your meter can very easily measure this.
Lnst primary - You cannot measure the inductance of an iron core
transformer with a simple battery powered meter. The transformer core
needs a substantial current (around 1/4 amp) at near the rated frequency
for the core to magnetize properly. However you can measure this. With
nothing connected to the output of the neon, find the no load current draw
of the AC input at the rated voltage.
Lp = Vin / (2 x pi x F x Iin)
In most cases, the fancy programs are very good at predicting all these
values. They are usually within 5%. After seeing how difficult some of
those values are to really measure, you can see why these programs are so
I am very surprised that your EMMC went UP in value! I have no exlanation
At 01:04 AM 8/6/99 -0400, you wrote:
>I measured my EMMC of 2 strings of 10 of the panasonic 1600V .056u at an
>actual 11.16 nF. That is UP(!) from right after its construction before
>its first use. Then it was 11.13nF.
>I also measured everything else I could clip my little meter leads to
> Measured Wintesla
>Primary .012mH .0179
>Pri & wiring .016mh NA
>Secondary 7.8 mH 7.6
>Cself 62pF 7.10pF
>Ctoroid 86pF 21.4pf
>Csparkgap .048nF NA
>C nst sec-gnd .038nF
>R nst second 5.95kO
>L nst primary 34.1mH
>DMM is a wavetek 27x and all values are adjusted from base reference.
>It looks like wintesla was VERY close on primary and secondary L, but
>either my meter won't go low enough or wintesla was wrong on the C's.
>Has anyone else measured this stuff? Do my other measured values look
>I finally got off my lazy butt and took some pics of my coil in
>operation. It's so easy to take non-operating pics with a digital cam
>that I have film cam motivation problems! Anyway, I used a $100 Pentax
>K1000 with manual everything, a pentax 35mm 2-22 f-stop lens, a $20
>tripod, f stop at 4, shutter on bulb. I ended up with the best combo at
>4 seconds. I used crappy Fuji 800 ISO film. Anyway, more info, along
>with the pics, is posted on my site. http://tesla.better-dot-org/sgd
>I think my coil is simply not bright enough to have a chance of getting
>away with 100 or 50 ISO. Shutter time would have to be around 12
>seconds or more and I'm already getting too many sparks for my taste.
>Next project is to set up the ol' camcorder then run the tape through my
>cap card and make some AVIs.
>Incidently, I accidently left my Kodak DC120 digital cam in the room
>while doing the manual pics and it was fine. It was about 8' away and
>probably saw a total of 4 minutes of the TC being on.