/diy/ - Do It Yourself

So I built this ckt up (from w2aew), but used an LT1394, 7ns comparator instead of the op-amp. The simulation seemed to work fine except for very low values of the charging capacaitor (ps anyone know why <100pF doesn't work well with RC oscillators).

Anyways, the ckt didn't work when I built it up, it just hung around the positive rail. Might have been a bad connection somewhere but the voltages made sense. Anyways, I replaced it with a RR op-amp and it now works fine. Is there a good reason why this wouldn't work with a comparator?? It's as if the capacitor got charged up before the ckt could begin to work.