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Re: [TCML] RE: Sound Modulated tesla Coils



Hey---

I'm using an annular blown gap for my 1800 watt TC. The blower is a vacuum cleaner motor. I had been running it on 120 VAC for mondo years, but on the basis of a recent post on TCML whose authorship I can't remember, I tried running the blower at lower voltages with a variac. I got all the way down to 12 VAC with no loss of performance. My rep rate is probably 20 or 30 pps, so it seems likely that this kind of arrangement would work up to at least the low hundreds of pps. I'm currently running the blower from a 35 V xfmr to provide it gentler service in its possible dotage. Being a series-wound motor, the low voltage won't hurt it. I couldn't find a blower with an induction motor that would come anywhere near the pressure, even in Grainger or McMaster-Carr. The air blows into the housing, between the electrodes, and exhausts through both hollow electrodes. Mine are made of Cu-W pressed onto brass tubing, but brass electrode surfaces would work well and give long service. My Cu-W has never shown wear in 22 years of service.

All this is to say that such a gap would probably make a good triggered gap for a musical TC with the addition of a triggering plane. A standard Maxwell triggered gap would work well too, blowing the air in one side, through the hole in the trigger plane, and out the other side. You would have to make some mechanism for adjusting the electrode spacing from the triggering plane, such as screw threads.

One of these Maxwell gaps can be seen on the Tesla Coil Builders of Fort Worth site,

    http://www.capturedlightning.org/hot-streamer/ross/TCBFW/TCBFW.htm

which as an excellent site with a lot of cool pix and info. I also found a surplus place that sells them for $125.00. (Dang! I had hoped to make a bundle selling a couple that I have. They are somewhat smaller than the ones on the web and a little more steampunkish. I would let them go for $100.00 each. End of shameless commerce section.)

If anyone would like a drawing and pix of my gap or ideas for modifying a Maxwell, let me know.

---Carl




-----Original Message----- From: mddeming@xxxxxxx
Sent: Monday, October 22, 2012 5:40 PM
To: tesla@xxxxxxxxxx
Subject: Re: [TCML] RE: Sound Modulated tesla Coils




Paul Kidwell at www.thegeekgroup.org has recently devised a way to play polyphonic music (up to eight voices) on a Tesla Coil. You might want to contact him. I think his email is: pkidwell@xxxxxxxxxxxxxxxxx Or, you can leave a message on the group website.

Matt D.


-----Original Message-----
From: Greg Cousen <lurch50@xxxxxxxxxxx>
To: 'Tesla Coil Mailing List' <tesla@xxxxxxxxxx>
Sent: Mon, Oct 22, 2012 5:24 pm
Subject: RE: [TCML] RE: Sound Modulated tesla Coils


Hi Mate,
Thank you for your reply, I have looked on the net but have not seen any
kits for the SSTCs, I have seen the rotary gap advertised as a kit, I will
keep on looking, here in Aust our voltage is 230 / 240 @50hz,
I will look into the variable frequency idea, thanks again :)

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Jim Lux
Sent: Monday, 22 October 2012 11:03 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] RE: Sound Modulated tesla Coils

On 10/22/12 1:24 AM, Greg Cousen wrote:
Hi Everyone,

Okay as new to this but totally wrapped in Teslas genius I am
experimenting with a few different things, info I need is where can I
get a diagram or schematic on how to build a musical tesla coil,

Also I have a power supply that I use to run ladders etc; it is run
from the output of an isolation transformer with a variable auto
tranny on the secondary side wired for boost voltage, so instead of
230vac I can get close to 300vac, can I run a coil from this, also I
have a ground earth setup totally isolated from mains ground earth
which seem to work well for other experiments I have done,


There are four ways, off hand, to get a TC that can play music.

1) for a static spark gap TC, the break rate (and hence the sound) is
controlled by the AC Line frequency.  You'll hear 120 Hz in the US, for
instance.  you could drive your transformer with a variable frequency
supply.  (there's a lot of tricky aspects to this..)

2) For a rotary gap TC, the break rate is controlled by the speed of the
rotor and the number of electrodes.  Change the speed of the rotor, and the
pitch changes. Or, figure out some way to select between rotors with
different numbers of electrodes (viz Hammond Tone Wheel organ)

3) A DC coil could be run with a triggered gap, and the trigger rate is
driven to control the pitch.

4) A solid state TC (SSTC) generates the HV pulses with hardware, and is
trivial to change pitch on.  I'd say that the vast majority of singing TCs
that you see on youtube, for instance, are SSTCs of one kind or
another.   The problem with a SSTC is that it's more complex than a
spark gap coil:  you have the high power transistors (IGBTs or FETs) and all
the drive electronics.  It's probably not a "assemble from your junkbox in a
few hours" like a NST powered spark gap coil might be.

There are people selling kits for DRSSTCs with music modulation inputs out
there.
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