JH's VCO

[Martin Czech]

Ok, I just wanted to give some hint, why the osc may get slow
at the very high end...

::::(3) Saturation / BE capacitance:
:::Wouldn't this capacitance be more or less just in parallel to the (desired)
:::integration
:::cap of the VCO ? (Have to check again - just "gut feeling" so far  ...)
:::

It is not about small signal capacitance, but carriers stored in the
base. It can be that the turn off takes considerable time, because these
carriers are removed very slow..
So the SCR discharge switch *may* have an undesireable dead time.

Ultrasonic:
I think a triangle osc is still the optimum choice for ultrasonic.
Simply because the amount of high frequency is minimised.

m.c.