Self-heating of crystal in inverter oscillator
 

Ben Jackson wrote:

It's a Digi-Key X231-ND, mfg p/n ECS-250-18-4-F. Digikey has the
datasheet. I think the ESR was 40 ohms.

Would you like me to post the results to my web site?

Sure.

Hi Ben,

I found the ECS spec at http://www.ecsxtal.com/search.html

The numbers a

Shunt capacitance C0 7pf

drive level 0.5mW maximum

max esr 30 ohms

Using these values plus the standard beta value supplied with the SPICE
model for the 2N3904, the oscillator runs pretty good. It doesn't clip, and
puts out a good signal to drive CMOS.

But the crystal dissipation is about 5.88 milliwatts, or about 11.7 times
the max spec value.

Since this is so far above spec, there's not much reason to go further and
spend the time to post the waveforms.

Regards,

Mike Monett