Audio Modulated Tesla Coil
This Tesla coil was designed to play
music. Plain and simple. Originally I wanted the best sound quality
possible from an analog source, and at the same time the largest
streamers possible. This lead to a long research phase where I tried to
find out what could give this combination with the least effort.
Several months passed with this project bouncing between ideas and
nothing happening, until a friend suggested I use MIDI to interface
with the Tesla coil. This is used in DRSSTCs and definitely gives the
biggest sparks, since the coil is run at full power and the pulse
repetition frequency is
just varied (see my Polyphonic MIDI Tesla Coil Interrupter project).
The disadvantage is that only square waves can be reproduced by the
Tesla coil when using this type of audio modulation. However I was
already using Steve Conner's PLL driver at this point, which
has analog audio modulation implemented! Since one wouldn't affect the
other, this driver has both analog and gated modulation.
The driver itself is pretty much
identical to the PLL SSTC 1 driver, which is to say Steve Conner's PLL
from his DWSSTC
. The additions I made for this particular SSTC
were to include an inverter for the interrupter signal, so a high
signal from the interrupter can either turn the coil ON or OFF. This is
used so the MIDI interrupter can play music the "conventional" way so
there are no streamers during silence, or so the coil can remain in CW
mode with a interrupter signal, and thus play music via frequency
shifting (analog). I purchased some UC3710T gate driver chips on ebay,
which come in a nice TO-220 package, much easier to keep cool than
dinky DIP8 gate drivers. Other than that there's not much new to anyone
familiar with this driver. I've made a PCB for the driver, but unless
you also acquire some UC3710T's it's not of much use. SSTC
specs on the coil for those who are
interested. This one draws 1kW of power when run in CW mode, and the
discharge is only 12cm tall or so. About the same size as the topload,
which btw, is two steel Ikea bowls. They come in small, medium, and
large, which is perfect for Tesla coiling although it would be better
if they weren't completely spherical. The reason the discharge is so
small for the coil size, is because I designed the coil to be run
continuously while audio modulated, and also provide decent audio
quality. This required the rather high drive frequency of 625kHz, and
not much power throughput or the IRFP450s would overheat. As is, the
only thing limiting the run time is secondary temperature, as the
electronics stay cool. A pleasant change from my other High voltage
projects, but in the end I wish there was some more bang.
Demonstration with MIDI Interrupter
I do not take responsibility for any injury, death, hurt ego, or other
forms of personal damage which may result from recreating these
experiments. Projects are merely presented as a source of inspiration,
and should only be conducted by responsible individuals, or under the
supervision of responsible individuals. It is your own life, so proceed
at your own risk! All projects are for noncommercial use only.
This work is licensed under a
Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.
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