Re: phase locked loop SSTC

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

Original poster: "Steve Greenfield by way of Terry Fritz <twftesla-at-qwest-dot-net>" <alienrelics-at-yahoo-dot-com>

A link to the MAX038 waveform gen, look down the page
for information on using it as a PLL, specifically for
"frequency-phase detector". It says that this
configuration is resistant to locking in on a multiple
and always starts at the lowest frequency in the
absence of a signal.

http://dbserv.maxim-ic-dot-com/appnotes.cfm?appnote_number=650

Perhaps a solution to using a 4046 PLL is to make it
have a fairly narrow auto range, but put a manual
coarse control. Or on absence of lock (like when first
turned on) another circuit scans it up until it gets a
signal. Otherwise, as one person pointed out, way off
frequency you get virtually zero signal back so there
is nothing to lock to. Am I making sense?

Using a PIC as one person suggested, you could tune
the VCO in the MAX038 (0.1Hz to 20MHz!) across a band
and look for the peak, then settle on the peak. The
PIC could then "wobble" the frequency up and down
slightly, keeping the peak in the center of the
wobble. This should then follow changes due to arcing
and nearby objects changing the resonance.

Steve Greenfield

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