Hi Kerry,
Yes, it is indeed possible to hi-fi audio modulate a SSTC. There a many topologies to achieve this, but each has pros and cons, especially when budget and parts availability is concerned. The easiest and cheapest topology is open-loop oscillator drive. This makes use of the standard feedback>gate-drive>GDT>inverter-bridge driver setup as-is with no modifications, you simply add a FM-modulated “front end” oscillator and feed that into the “feedback” of your Schmitt trigger as you would have fed in the antenna/CT previously. Adjust the clock frequency of your oscillator with low level audio signal, aiming to keep the frequency deviation within the FWHM of your resonator’s bandwidth.
Running closed loop feedback proposes challenges for quality audio as the intrinsic phase shift causes heavy harmonic distortion of the audio. This is why PWM modulating the enable lines of the gate chips rarely results in suitable hi-fi audio modulation.
see my engineering blog for more info: www.SigurthrEnterprises.blogspot.com
here’s the paper I wrote about audio modulation of a SSTC: http://sigurthrenterprises.blogspot.com/2014/02/a-treatise-on-audio-modulation-of-solid.html
here’s a few videos of my small/portable SSTC with my hi-fi modulator attached:
https://www.youtube.com/watch?v=qbB5jSTM4pQhttps://www.youtube.com/watch?v=4-zt-P_nbuIhttps://www.youtube.com/watch?v=dLC8Et5yYLYhttps://www.youtube.com/watch?v=H01G9ia__Ic
as you can see in the last video link, even low frequency bass notes are reproduced accurately without intense roll-off. Coil runs at roughly 350KHz putting out 300W CW unmodulated, or about 150-225W when playing audio. Unlimited duty cycle, loud enough for a small room to comfortably listen.
Sincerely,
Matt Sigurthr Giordano
7. Audio modulated sstc (Kerry Soileau)
Message: 7
Date: Sat, 27 Jun 2015 01:53:43 +0000
From: Kerry Soileau <kerrys@xxxxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Subject: [TCML] Audio modulated sstc
Message-ID: <9A17ABB2-2E3B-44E0-960E-BAB69D5EC7A2@xxxxxxxxxxxxxx>
Content-Type: text/plain; charset="us-ascii"
Hey guys, well first off I want to ask a question about audio modulating a sstc in a different way. I've finally finished my first sstc and I'm pretty impressed with it. I managed to audio modulate it with an arduino sending pulses to a fiber optic transmitter then over to the receiver and then to my gate drivers. My sstc is a half bridge config with a 74hc14 for feedback and then a ucc31/32 driver chips. I can give more detail if needed. Anyway, I'm not really that advanced when it comes to programming so I've only managed to program using the tone function as of now. The sounds are monophonic and they kinda suck. It's cool but for some songs I want to play(converting sheet music) I need to play multiple notes at the same time which has proven to be quite hard on the arduino UNO. Long story short, is there a way to take an input from my phone over auxiliary Jack and send that signal to my fiber optics and I turn over to my driver circuit. Diagrams always appreciated lol. Tr
ied a few op amp circuits but I come up empty every time. My goal would be able to get rid of the arduino and just play straight from my phone or iPod. Saw a 555 fly back circuit that the guy was playing songs over the arcs from his iPod nano. Had words and everything. Is this possible on a sstc?
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla