The AD790 datasheet shows that the logic supply range is 4V to 7V... So no, it can't be powered by 3.3V.
There are other comparable comparators that you can consider, such as the AD8468/ADCMP608.
The problem is finding a new part that runs on +/-15V and is in a PDIP; there aren't any.
Look at the AD8469, AD8468, ADCMP609 or ADCMP608. You can get little adaptor boards
from sparkfun.com and solder SOICs on it and plug it in a…
O.K.! you definitely need a comparator, not an op amp. An op amp has an analog output stage and is usually compensated
for unity gain stability, so it is slower than a comparator. The more you overdrive an op amp output into into the…