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Re: [TCML] Small tesla coil design

You might also be able to figure out a way to make inverters that can 
drive NSTs at different line frequencies - Nothing's sacred about 60Hz, 
after all.

Be aware, however, that if you drive a transformer at a significantly higher frequency than it is designed for (i.e. 220Hz for an A3 note rather than 60Hz), your core and winding losses will increase substantially and your efficiency will drop. You will lose a lot of power in the form of heat in the core and windings. Perhaps this won't be a huge deal in yourcase, and you may be able to account for the additional losses, but just be cautious that the transformer will not work as well at higher frequencies.
Matt, Fairlee VT

-----Original Message-----
From: jimlux <jimlux@xxxxxxxxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Sat, Dec 29, 2018 10:43 am
Subject: Re: [TCML] Small tesla coil design

On 12/28/18 8:32 PM, Dirk Schmidhofer wrote:
> Greetings TCML'ers!
> I can't exactly declare myself a long-timer, but have been lurking the list
> for several years.  I haven't built my first TC yet, but am on the verge.
> I was wondering if there might be a reliable design I can sort of mass
> produce for an art project I'm working on.  I've been making various art
> installation contributions to Burning Man for a dozen years now, and I have
> the prototype for what I call the Kosmik Kalliope (Kosmik Dust is my
> Burning Man theme camp, so please pardon the awful spelling abuse).  The
> Kalliope currently is a flame effect piece; please see the prototype 13
> second video here:
> https://www.youtube.com/watch?v=-8sDM2_J9J8&feature=youtu.be
> I have a custom microprocessor that receives MIDI and switches the solenoid
> valves accordingly, 12 pipes for the 12 notes of the chromatic scale (it
> rolls over and plays regardless of the octave a la MOD 12 calc.).  I've
> fashioned a custom igniter so I don't need pilot lights.
> I am licensed by the Nevada State Fire Marshal to operate flame effects as
> well as a pyrotechnics license and I do commercial stuff but my true love
> is to take art to Burning Man. (o:
> I've been gathering parts for awhile now (NSTs, MMC and Terry Filter parts,
> etc.) and I know it is highly recommended to build a SGTC before tackling
> the solid state stuff, but I've also finished building several of Eric
> Goodchild's UD2.5 boards I've had laying around for awhile because
> sometimes I don't work linearly (o:
> My question:  (Sorry for long windedness); I would like to build 12
> relatively small Tesla Coils (or 24), and was thinking they might be static
> spark gap units that could be displayed either above or alongside my Kosmik
> Kalliope pipes and switch them on and off reliably, like I do the flame
> effects?  Not looking for massive streamers (6-12"?), but I would like them
> noticed by the audience.
> Is there an available design out there that might meet my intentions, or is
> this just a crazy idea, whereby the things will strike my stuff and blow up
> all my other electronics?? (o:  They would of course be on stands far away
> from audiences.
> I would like to switch them quickly but I'm not interested at this time in
> actually doing the MIDI modulation; just turn them on and off, as there's
> lots of other music playing already.
> I have ten Allanson NSTs (12K 30mA) that are unfortunately GFI and potted,
> but perhaps could use them the way a previous TCML contributor used them
> with that resistor network he described?
> I also have three other NSTs (nonGFI) larger and smaller.
> Or perhaps MOT TCs would be the way to go?
> Or a simpler solid state design whereby I could power them all off one
> large power supply?
> I have a modest machine shop with lathe, 2 hp CNC mill and 3D printer so
> I'm not afraid of fabricating.
> I've toyed with the thought of designing, but as a first-timer, I seem to
> get stumped with a chicken or the egg thing as far as where do I start?

this is a way cool idea..

One thing you might be interested to know is that flames are 
electrically conductive, so you've got some interesting effects you can 
do combining flame and HV, aside from the tesla coil thing - for 
instance, a jacobs ladder with a flame is very interesting...

For just keying on and off, a suitable relay in the line voltage supply 
is probably the easiest way. I'd try a decent industrial application 
Solid State Relay first (because it gives you optical isolation from 
your MIDI equipment), but it's possible that HV RF spikes coming back on 
the power line might kill it.  A bit of experimentation is needed.

With this you can do effects, oh, like the Bellagio fountains, turning 
different coils on and off in patterns, and you could probably figure 
out a way to change the power level for the coils too.

One other idea that's been bandied about over the years is to have an 
array of DC tesla coils run by rotary gaps, with different numbers of 
electrodes on the rotor, or running rotors at different speeds, so that 
the coil's audible buzz frequency is tunable in a scale.  For instance, 
rather than all your coils buzzing at 120 Hz (typical for a static gap 
running off a NST), you could have a coil running at 110 Hz (A2) one 
running at 130.8 HZ (C3) on running at 164.8 (E3) and so on..

To make this work, you'd need a nice DC power supply to feed all the 
coils and a way to turn individual coils on and off - a air operated 
mechanical switch would work nicely.

You might also be able to figure out a way to make inverters that can 
drive NSTs at different line frequencies - Nothing's sacred about 60Hz, 
after all.

Most of the "musical coils" you see out there use solidstate drivers to 
accomplish this.  There's a lot more complexity in a SSTC, but they do 
work well.

Finally, another way to fire the coils is with a triggered spark gap - 
that lets you fire at a specific rate (for the musical note)
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