Re: SSTC Singing Arc Design - Help needed

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Daniel Barrett by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dbarrett1-at-austin.rr-dot-com>

    You might try the following:
    Run your audio signal through a comparator (zero crossing detector) so
you have a rough square wave version of the original audio. Use this signal
to trigger a fixed pulse width one shot (say, 20uS or whatever your current
maximum pulse width is with your TL494. You can make this circuit with a
'741 op-amp and a 74HC4538. This gives you a bunch of 50uS drive pulses at
the audio rate.
If this sounds like something you want to try and need more detail I can
send a rough schematic if you want-

db

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, September 11, 2002 1:49 PM
Subject: SSTC Singing Arc Design - Help needed


> Original poster: "Mccauley, Daniel H by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>
>
>
>
> Well, I'm off to begin my SSTC Singing Arc project.  I checked out Richie
> Burnett's site and Alan Sharpe's site but didn't really find anything
useful
> as far as an actual implementation of the circuit.  So I think i'm on my
> own.
>
> The first thing I need to do is get a DC input to my power supply circuit.
> For this, I'll just use a full-bridge rectified mains (115VAC) with some
big
> caps for smoothing filters.
>
> The next thing is I need to figure out how to implement am modulation (via
> audio signal) to my FET drive circuit.  Right now
> I'm using a TL494 PWM Driver IC.  Someone how I need to am modulate the
> output of this guy.  Anyone have any ideas???
>
> Thanks
>
> Dan
>
>
>