Recently, i see such a circuit in a board schematic, but can't figure out how it works, why the first Op Amp has positive feedback ????
Question, again, now i complete the circuit with part number and values, just as below.
By simulation with PSpice, i know the "AC coupled" negative input of the comparator is to synchronize the oscillation frequency of the generator. But it seems there is one 'working window', if the pulse rate is two high, the output wave form will be oscillation on the amplitude.
I want to know if this a 'classic' or a widely used technique. And i want to know if there are some accurate mathematical method to predicated the behavior, particularly the synchronizable frequency range.