Re: phase locked loop SSTC

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

Original poster: "Jan Florian Wagner by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jwagner-at-cc.hut.fi>


> Well, I don't understand this. John doesn't seem to be giving any
> hints, maybe you can explain?  How can you tune the VCO with just an
> amplitude feedback and a comparator?

My guess is: on startup the VCO input is placed at max voltage and the
output frequency is the reso freq. Then when the sec reso freq starts
going down, driver and sec detune, sensed voltage goes down, and so
will the voltage into the VCO which then leads to that the VCO output
freq goes down as well. In tune again.

Ok but I'd appreciate a schematic of this, too! Don't have any idea
what the comparator is doing...

By the way, phase locked loop seems to work if and only if the upper
freq of the VCO is set to the unloaded reso freq of the secondary and
the lowest freq is maybe 50kHz below this (300kHz coil). (not a
"plug'n'play"-for-any-secondary thing like I had wished...)
Current sensing from the secondary bottom instead of the primary coil
really did show an improvement! Thanks for the tips!

cheers,
 - Jan

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