rickman wrote in :

I only need it to turn the input signal
into a one or a zero, but it needs to be sensitive to a very small
signal.

My widget was aimed at exactly this need. That's why I recognised a new
need. My original need was for an electret mic. but it had to be so sensitive
I could whistle gently with barely pitched sound on the other side of a
quiet room and have it track like a fighter jet's navigation. It was a lovely
combination of sensitivity and clean reliability too, intended as the front
end control of an electronic musical instrument. I'd used a bit of gain and
bandpassing before the CA3140 Schmitt trigger, but in the case of time
signals I doubt it would need this extra preprocessing. Just add a cap and
resistor on output to integrate the 60KHz into clean slow pulses.