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Re: [TCML] Audio modulated coils: where to start?
Curtis, thanks for your input.
When you talk about PRF do you mean it uses pulse width modulation? And does
this second method restrict one to monophonic sound? By 'complex' do you
mean polyphonic or 'full' bandwidth music? It would seem that the
plasmasonic boards produce small but polyphonic plasma. Daniel's other
board, the xenosonic seems to be monophonic but adaptable to many SSTCs. I
assume this in the second group you mention.
At this stage I think I will refer to Steve Wards site or info on building a
medium SSTC (full bridge maybe) and consider purchasing the xenosonic as a
way to modulate, or build a simple zero crossing setup. Being able to plug
in a guitar/keyboard or my theremin is very attractive and more versatile I
think. BTW I quite like the nasty distorted tones commonly heard on these
coils, but only playing one note at a time is a bit limiting.
Are you producing your own boards using Steve's designs or just using
veroboard etc. I notice that Steve has a lot of copper on the upper side of
his boards. Looks like double sides boards. Lots of current sinking? ground
plane?
Good luck with the build. Talk to you soon.
Dave Nelson
----- Original Message -----
From: "Curtis Cherry" <willworkforgas@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Saturday, May 31, 2008 2:37 AM
Subject: Re: [TCML] Audio modulated coils: where to start?
Hello everyone. My name is Curtis Cherry
Let me start out by saying that I have not ever actually built a tesla
coil, but I have been researching them for over a year now. I have
concentrated on the SSTCs because I too intend to audio modulate some day.
If fact my interest in tesla coils was spurred by the video of Steve Wards
DRSSTC2 on you tube playing super mario brothers.
As I said Ive never built a tesla coil but I will share the info I have
learned. Most of the info comes from Steve Wards site www.stevehv.4hv.org
Just click on musical tesla coils.
There are 2 basic forms of audio modulation. Amplitude Modulation is
the first type. It works by changing the duty cycle of the output of a
coil while it is oscillating at its resonant frequency. This changes the
amount of total power going into the coil. Changing the amount of power
going into the coil changes the volume of plasma being produced which in
turn causes the air to contract and expand. This creates pressure wave
that we hear as sound. This technique works the best with a CW(Carrier
Wave) coil. The amount of total power in CW mode is quite considerable
and I am not sure if anyone makes silicon that handle the amount of power
it would take to make 2 foot sparks for any considerable amount of time.
This type of coil is capable of faithfully reproducing audio.
The second method of audio modulation is PRF (Pulse Repetion
Frequency). This coil fires "bursts" of plasma out at certain frequencies
to create pressure waves. This type of coil suits itself well to any
pulsed type of tesla coil such as DRSSTCs. This is the type of coil you
want to build if you want big sparks due to the lower average power
output, but the audio is quite a bit more harsh and doesnt lend itself to
playing "complex" tones. Steves coil runs off of a microcontroller to
create the pulses but it would work just about as good to use a
"zero-crossing" circuit hooked to a keyboard or any other audio source.
You can also get some good info from A guy names Dan McCauley (Sorry if
I spelled it wrong). His site is www.easternvoltageresearch.com He sells
TC driver boards if you dont want to start from scratch. He also sells
audio interfaces that can work with any type if SSTC. And boards for an
audio modulated coil called the "plasmasonic".
Please keep in contact with me throughout the process of planning and
constructing your coil so that we can share ideas and information. I have
accumulated all the parts to build my coil and will start half-bridge
construction soon. Good Luck to all.
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