hi,
am analysing an already existing circuit which is supposed to count the no. of pulses generated by a flow sensor and feed it to the counter input of microcontroller to measure flow which is proportional to the flow... now what beats me is they pass the pulses thru a schmitt trigger circuit using opamps... then pass the signal thru a Low pass filter n then again pass it thru a schmitt trigger inverter... i mean y not directly pass it thru a schmitt trigger inverter... am totally clueless... thats question no 1.
question no 2 is... once i get neat square pulses they are passed thru toggle f/f to divide the freq by two n then its gated with a high freq signal of 3Mhz before feeding it to the microcontroller... now the question is my input signal (which is in form of pulses) has varing freq (range 0-150 hz)... so the no. of 3mhz pulses gated at low freq are high and at high freq are low.. so how do i count the pulses and its freq????.....