I want to build a phase-lockable VCXO using one of these tiny 100 KHz tuning fork (cylinder-type) crystals:
I've got it to oscillate using the classic unbuffered CMOS inverter circuit with a 5V supply, two 33pF loading caps, 1M feedback resistor and 100k current-limiting resistor. This may still be too much drive - the datasheet says 1uW max.
Is this a suitable circuit for these crystals? Can anyone recommend a better circuit?
TIA
Check the input side of the inverter with a hi-Z 'scope probe. If it's significantly less than rail-to-rail and looks sinusoidal you should be OK.
...Jim Thompson
ing
it
sheet
that was the easy part..
now how are you going to make it voltage controlled?
Mark
OK. Simply make a voltage-controlled capacitance multiplier ;-)
...Jim Thompson
'tis why varicap diodes were invented. But you'll have to use another inverter (preferably a Schmitt) and some discretes to provide 15V or so.
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