On 3/21/19 9:33 AM, Adrian Caspersz wrote:

After a quick google, I found this paper.

Â*Design and Construction of 1kVA Inverter
Â*http://www.ijeert.org/pdf/v2-i3/29.pdf

and also

Â*250W PWM inverter circuit SG3524
Â*http://www.circuitstoday.com/pwm-inverter-circuit

Hello, and thanks for the above link and the others! Looks like those
designs depend on R-C time constants rather than crystals. And
crystals, like resistors and capacitors can age with time. Whether or
not those designs you referenced are employed in inverter generators is
TBD. It's not so much an issue which time-base (oscillator frequency)
works better when new at room temp but how it behaves in the outdoor
operating environment of temperature, humidity, vibration,
rough-handling, etc, including component aging. Mea culpa for posting
design questions to a repair ng. Sincerely,

--
J. B. Wood e-mail: