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Re: Terry's DRSSTC - Controller Experiment

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>


Antonio is right, as the coil is de-tuned, the top voltage tends to stay rather constant but the primary current tends to rise dramatically!! I think Steve reported he could run with a very highly detuned coil but I suspect he was driving far higher current through is big IGBTs.

I am tuning my DRSSTC by finding the point of least current draw. On both sides of Fo the current goes way up. It seems at the best tuning the current draw is the lowest.

I am not concerned about which mode it is in since the drivers do not care and I really don't care either ;-)

I think I can run my old Magnifier with the DRSSTC driver too. I may have to make a new top holder since I think I "borrowed" that from the magnifier. With the DRSSTC now, the magnifier should be far easier to study.



At 07:59 PM 4/19/2005, you wrote:
Tesla list wrote:
Original poster: Steve Ward <steve.ward@xxxxxxxxx>
I suggest you retune your primary to get rid of that primary notch.
Tuning it lower will make the primary ring up continuously, and will
give longer sparks, though you wont see them till you have many cycles
I cant imagine how that minor phase shift on the very first cycle
would matter.  I think what matters more is that your primary current
is notching about a cycle later for the longer sparks.  Have you tried
tuning the primary lower?  This seems to lengthen the time between
notches in the primary current (until you get to 0 notches).

The notches mean that the system is tuned in a way that at some point transfers all the stored energy to the secondary system. This results in operation, before breakout, as in a conventional capacitor-discharge Tesla coil. Without notches, the driver frequency is close to one of the resonances of the system. The output voltage may get higher, but the input current invariably gets disproportionally higher, and some of the energy never leaves the primary circuit. A system operting in this way can always be redesigned to produce the same output voltage, and energy, faster and with less input current, with notches in the primary current and voltage. After breakout, if the driver is kept running, the notches disappear.

Antonio Carlos M. de Queiroz