Re: SSTC Singing Arc Design - Help needed

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Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Dan,

On 11 Sep 2002, at 12:49, Tesla list wrote:

> 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???

Usually one feeds a regulated DC voltage into one of the opamp inputs 
to give a reference standard. You might try to feed an audio signal 
into this input so that it varies about its DC mean (which should be 
arranged to set the duty cycle to 45%).

?
Regards,
Malcolm