FREQOUT 4mhz

[Michael]

and that should be 127, not 50 for duty cycle -- typo

[Michael]

I think it may be this crap piezo I'm using --

https://www.ebay.com/itm/US-Stock-50...72.m2749.l2649

hard to work with. maybe someone can suggest an inexpensive one that they know works well. need low cost as this may be a product idea. 6500 hz is pretty high as well.