[sdiy] Ultrasonic VCO question for Ian Fritz (or whoever)

[Scott Bernardi]

I direct this question to Ian Fritz, since you are the author of an
Electronotes EN #112 article on a Ultrasonic VCO (built with a 3080,
JFET buffer, and LM318 schmitt trigger). Anybody can answer.
In the article, you say you compensate for the 570nS dead time with a HF
track trimpot in series with the integrating cap. The Mikulic style
sawtooth oscillators use the same scheme. You suggest a value of around
4K total.  What is the formula for calculation of this resistance?
Doesn't seem to be t = RC,   R = t/C.