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Re: [TCML] static gap singing coil hybrid.

Oh yes, that makes sense... If I get impatient I'll probably just make a resistor out of a bucket of salt water and some metal plates, very inefficient and short lived but I imagine it will prevent inrush to the gap and still allow the tank cap to charge. It will be some time before I build a prototype as I have no idea how to interface with midi, though I suppose I could rig a 555 timer with about 4% duty cycle at 30Hz-5khz to trigger another driving a flyback at 100 kHz to be my trigger, that way I can get at least steady sound, pitch adjustable with a potentiometer as proof of concept, and not worry about midi until later. 

Scott Bogard.

On 1/25/2011 9:33 PM, Phillip Slawinski wrote:

Scott,

The MOTs will probably work.  Also the charging inductor serves the purpose
of limiting the current from the filter capacitors when the spark gap is
triggered.  Remove the inductor, and you end up dumping the the filter
capacitors across the spark gap when it's triggered.

-Phillip

On Tue, Jan 25, 2011 at 17:55, Scott Bogard<sdbogard@xxxxxxxxx>  wrote:


Phillip,
        I was planning on eventually building a DC coil eventually anyway,
and I have enough microwave oven capacitors and diodes that I could build a
MOT based level shifter with all the current I can handle, not sure if that
would cut it or if I would need a resonate charging inductor, which could be
made with more MOTs in theory.  Since it is triggered it shouldn't need an
especially high voltage I suppose, so 4kV was where I was aiming.  The
biggest hurtle I see is cooling, having that arc that close to glass for
prolonged periods will be tricky, but maybe if I run cold air or oil or even
water through the tube, its life expectancy should be similar to glass jar
capacitors I'd imagine, even if I only get 15 minutes out of it glass tubing
is a lot cheaper than IGBT's, and is easy to replace...

Scott.


On 1/25/2011 1:13 PM, Phillip Slawinski wrote:


Scott,

While this looks okay in theory, there would be some limitations.  The
main
limitation would be that this could only work with a DC charging system.
This adds complexity to the project, because you must then locate large HV
filter caps, diodes, and a properly designed charging reactor.  Aside from
those issues, I don't see any fundamental reasons why it can't be done.
  If
you do this please share your results.

-Phillip

On Tue, Jan 25, 2011 at 11:44, Scott Bogard<sdbogard@xxxxxxxxx>   wrote:

  Greetings all,

     So I was looking at this web page today at work for no particular
reason...
http://www.glacialwanderer.com/hobbyrobotics/
If I am understanding this correctly, he essentially built a spark gap
triggered by the corona around the inner glass tube from his trigger
coil.  If that is correct would it be terribly easy (if extremely
inefficient) to make a singing coil by constructing a similar spark
gap (with better cooling for actual run times) and just trigger the
inner coil with a midi signal.  This way for those of us who don't
want to tackle DRSSTC yet, can just build essentially a midi triggered
flyback, to gain familiarity with the audio interfacing without the
added complication of going strictly solid state, and the expense of
IGBTs.  Has anyone tried this?

Scott.
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