Re: SSTC - Self-Resonant Systems with Audio Modulation

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

Original poster: dhmccauley-at-spacecatlighting-dot-com 

The problem is that most self-resonant systems either monitor the current
going into the driver or use an antenna (such as Justin's circuit) to
monitor output power of
the resonator.  In either case, the circuit is a simple feedback circuit
that adjusts the driver frequency so that maximum current or maximum power
is detected at the
current sense or antenna.

In an audio modulated circuit, this will not work.  Since the circuit is
being power modulated by audio, the input current and output power of the
resonator will vary
according to the audio being fed into the SSTC.   You can then right away
see the problems the existing type of feedback circuits will have.

Perhaps the antenna feedback circuit could be modified to monitor only a
very narrow band of the SSTC output frequencies and then averaged over a
relatively long time.
This averaged signal could then be compared to some reference and small
frequency changes could be made to maximize power output.

Would be a challenge though.

Dan



 > Steve, why wouldn't a "self-resonant" system work for a audio modulated
 > SSTC? I think that a resonance "correction" circuit could be quite
 > useful. But I am not sure how to do it. The TL494 seems to be a less
 > then perfect IC for modulation, but Dan has proven it to be more than
 > capable! I wonder if it would be possible to do modulation with the
 > IR2153D IC that Dave Sharpe has been looking into? BTW, where to find
 > this IC? I have checked the usual suspects, but haven't found... What
 > are folk using to design their boards, Eagle? But finding the right
 > component list is troublesome! Arggh! I wish I actually had some time to
 > spend on this. My desire is to make my own board, starting with a vary
 > simple "half-bridge" circuit. The challenge of solid state is a very
 > luring one that makes VTTC look like child's play! Absolutely no room
 > quick lash-up's Those IC's are truly infant weak!
 >
 > Regards,
 >
 > David Trimmell