On 3/22/19 1:25 PM, Ralph Mowery wrote:
In article ,
says...


The cost of small microprocessors and crystals are almost nothing. Look
at the Arduino processor boards. They can be bought from China for
about 2 ot 3 dollars. They are powerful enough to run the inverter part
of the inverter.

No sensible manufacturer is going to use a crystal` where they can use a ceramic resonator or a silicon oscillator built into the chip. And no sensible mfr is going to pay for a crystal plus a divide by massive number circuit when they can use a low frequency oscillator. If you can't see why there's nothing further for us to
discuss.



I guess that I used crystal too loose. Anyway the small processors and
clock circuits for them are very inexpensive.

Digikey has for sale crystal oscillators that can be programmed for most
any frequency for around 2 to 3 dollars. I have even ordered them
already programmed for about $ 4 each. I am sure in quanties of
thousnads from the manufactor they are very inexpensive.



If the processor itself is timed from a crystal many uPs give the option
of scaling down the system clock via a hardware divider to generate a
reference clock for whatever purpose u need