Hi Greg,There's no need to probe your primary circuit in order to measure quenching performance. You can tell exactly when your coil is quenching by simply connecting your scope to a small wire antenna that's placed well outside of the sparking range of your coil (see John Freau's earlier post). You'll need to carefully set up your scope's trigger and timebase so that you can view a complete bang on your scope every time the gap fires. When set up properly, you'll see one or more sine-like RF envelope "humps" that progressively become lower in amplitude. By counting the number of humps on the secondary waveform, you can directly determine when your primary gap is quenching.
If your gap fails to quench, bang energy will continue to cycle back and forth between primary and secondary LC circuits, continually losing energy all the while. Once the gap quenches, the energy interchange process stops, and all the remaining energy becomes stranded within the secondary circuit. The remaining energy then decays within the secondary circuit (ideally mostly through leaders/streamers). If you could achieve a single-notch ("perfect") quench, you'd simply see a single secondary-side ring-up followed by a much slower decay (from Richie Burnett's excellent site):
http://www.richieburnett.co.uk/quench1.gifIf your gap quenched on the 2nd notch you'll see two secondary peaks, with the secondary decay occurring just after the 2nd peak. And so on... Here's an example of 3rd notch quenching from Richie's site:
http://www.richieburnett.co.uk/quench2.gifI also agree with John - "perfect" single-notch quenching is not essential to obtain excellent coil performance. A given spark gap coil will show considerable quenching variation based upon the operating power level, degree of streamer loading, coupling coefficient, etc. You'll also see significant quenching variation from bang to bang even at a fixed power level, especially when using a static or asynchronous rotary spark gap. A very well written in-depth discussion about quenching can be seen on Richie's site:
http://www.richieburnett.co.uk/operatn2.html The bottom line:There is simply no need to risk your scope (or potentially your life) trying to measure your primary circuit when a simple secondary antenna will provide you with similar quenching information.
Bert -- ********************************************************************** We specialize in UNIQUE items: coins, shrunk by ultrastrong magnetic fields, Captured Lightning (Lichtenberg figure) sculptures, and scarce technical Books. Please visit us at http://www.capturedlightning.com ********************************************************************** G Hunter wrote:
Howdy Scot,hey Greg.. If your coil is putting out streamers comparable to other coils of the size and power, its quenching :)Sure, it's quenching somewhere, but where? 1st notch? 4th notch? I want to see for myself. It's not an urgent matter. I'm just curious. Also, good sparks don't automatically imply good quenching. While analyzing his single static sucker gap, Gary Lau discovered that even with crappy quenching, a Tesla coil can produce satisfactory streamers. Hey Gary, how did you scope that without killing your scope?Attempting to put an O-scope on a primary ( or even near a primary) could lead to the death of the scope...Yeah, I've thought of that. My scope is a Japanese relic from the late 70's. I gave $45 for it. If it croaks, I'll get over it. What about optical probing? Could I rig up a photo diode coupled to the input channel on my scope and let it "watch" the spark gap? Does the spark gap arc accurately reflect spark gap performance?hi voltage from the supply itself, EMP EMF from the primary, inductive voltages etc... are things to consider O-Scopes, even tho most are shielded, can be influenced by exterior sources. Mine can give erratic readings if I have a fluorescent lite too close to it. See what other people have to say about protecting a scope in thatsituation.... Ive never done it due to the fear of trashing mine...Scot DCheers, Greg_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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