[TCML] Thumper, the worlds most advanced tesla coil.

["Finn Hammer" <f-h@xxxx>]

All,

Thumper has finally found it's final form:

http://www.hammertone.com/temp/Thumper.jpg

(the little people gave a helping hand during the final stages)

http://www.hammertone.com/temp/litle%20people.jpg

The first picture holds a lot of mythological significance to me. When I  
started coiling, a decade ago, I came across this picture:
http://www.pupman.com/current/rstephens/MTC-A1.JPG
And I thought:"This can only happen in the States". Now, look at me  
standing next to Thumper.:-)

Thumper is what I believe to be the worlds most advanced Tesla Coil ever  
built.

The main feature of the coil started out to be the Predikter driver, which  
I posted about last year. This is the driver that predicts the primary  
current zero crossing, so as to initiate the switching of the bridge in  
advance of it, with the purpose of avoiding voltage transients. These  
transients occour because, if no measures are taken against it, the  
freewheling diodes will start to conduct and they will then be forced into  
reverse recovery when the bridge switches. This forced recovery shock  
excites the buss and creates a mess of high Q ringing. So it was a very  
valuable development there, and it has already become the standard of  
DRSSTC controllers used by the leading designers.

This was developed with a less than desirable primary circuit, so a  
suitable design of this commenced.
Since I invented the RAT technology some 8 years ago, I have wanted to  
apply it successfully. The original "Ambassador" coil was not a success  
due to my limited ability to controll the motors that position the  
variable elements.

In this latest version of the RAT technology,  both coupling and Tapping  
can be adjusted *on the fly*. The motor controllers for these 2 function  
are 2 fiberoptic connected atmega 328 microprocessors. I am indebted to my  
adversary, fellow coiler and friend, Daniel Uhrenholt, for constructing  
these controllers.
During first light, which happened last evening, we recorded this video,  
which to us, justified a year of work:

http://www.youtube.com/watch?v=71hpP56JwGg

It shows the primary current waveform, while we sweep the tapping point  
from 1/2 turn too low, and up to the sweet spot, where the notches appear.  
Notice that the current has dropped to half value by then, but the  
streamers have developed from 10 cm to 1 metre. With the notch in view, we  
then reduce the on-time till it coincides with the notch, and while this  
does not reduce the streamer, it reduces power consumption.

We did not write down the voltages and currents because we wanted to watch  
the tuning from the artistic point of view. I built the coil to be able to  
watch the primary current on the scope, to get an intuitive understanding  
of the tuning.

And Thumper payed back in silver dollars!

The sweet spot occupies less than 5 cm on the primary, so we might well  
have missed it by manual tuning.

Building this coil has beeen an unprecedented pleasure, so an abbreviation  
to describe it would not suffice, an acronym had to be pinned on it:

I have setteled for this:
Dual Resonant realtime Adjustable Solidstate Tesla Instrumentation Coil

DRASTIC

If this post have got you interested, a thorough documentation can be  
found on 4HV.ORG in the Projects board. Look for "Thumper"

Cheers, Finn Hammer
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