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Re: o-scope tuning of tesla coil?

Original poster: Finn Hammer <f-h@xxxx>

Mr. Black Moon

Instrument tuning of a Tesla coil is done in 2 steps, where the first step is measuring the resonant frequency of the secondary the other is adjusting the primary to the same, or a slightly lower frequency.

First, place your secondary with topload, separate from the primary, and elevated to the same height from ground as when it is going to operate. Attach the signal generator to the ground lead from the coil. From software (like Wintesla) you know approximately which resonant frequency to expect, so set signal generator range accordingly. Scope probe hook is grabbing 4 inches of bare wire and suspended from whatever, approximately 1 yard from the coil`s hot end. Adjust sensitivity and sweep to get a reading, which will be a sine wave.
Now sweep the signal generator and watch the scope. At some point, the output from the coil will rize to a much higher level than at frequencies just a bit higher or lower than that: it peaks. This is the resonant frequency, write it down. While you are at it, put your hand close to the coil, and get accoustumed to the fact that this frequency changes due to capacitive loading from your presence.

Now, move over to the primary circuit, place a cliplead or some other short across the sparkgap, and hook the signal generator across the capacitor. Likewise, place the scope leads across the capacitor. Now sweep the signal generator to find a peak, write down the frequency.
If it is higher than the secondary frequency, you need to tap out on the primary coil, adding turns and inductance, to lower the frequency, and vise versa, if the frequency is lower.

Now, since the coil will operate with some streamers from the topload, and since these streamers add capacitance to the top, bringing the secondary frequency down, you might as well take this into consideration right away, and tune the primary 5-10% lower than the secondary, to provide a good starting point.

Now assemble the coil and let it rip, chanses are you won`t have to change the tapping point anymore, although you should to get the feeling of how things are.


Cheers, Finn Hammer

Tesla list wrote:

Original poster: "Black Moon" <black_moons@xxxxxxxxxxx>

hmm.. im not sure if this is working... even adding a few turns on the primary seems to have little or no effect, can't seem to get primary/secondary tuned quite right... anyone know how to do it with both secondary and primary hooked up? (osilator to primary) and what the o-scope pics look at diffrent tuneing levels? seems to be getting about a 10x voltage gain and the secondary voltage is peaking in a few cycles (7 or so) with high coupleing...

From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: o-scope tuning of tesla coil?
Date: Fri, 31 Dec 2004 15:30:04 -0700

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

Get a simple signal generator like this one:

http://hot-streamer.com/TeslaCoils/Misc/TCT/TCT.htm

Probably just hook the scope across the LED. For the secondary, just hang a wire near the coil which will easily pick up a signal when the generator is near the coil's frequency. All the signals will change dramatically when they are near the tuned point. Just driving it all with a low power signal will not endanger the scope or anything.

Cheers,

        Terry


At 02:22 PM 12/31/2004, you wrote:

Hi, I just got a new analog storage solid state o-scope, and I have heard that it can be used to tune a tesla coil, How exactly do I go about doing it tho? I know the basics of operateing my scope allready, and I assume I need a low voltage osilator and can build one of those, but how exactly do I test tuning with those?