Posted on Mar 18, 2013 8860
This window comparator generates an output pulse for each event that occurs within a specified window. That is, each output pulse signifies an input voltage pulse or level change that exceeds VREFLOW. but not VREFHIGHÂ· The monostable multivibrators, IC2A and IC2B, produce a 10-l`s pulse at their Q output in response to a rising edge at their A input. Comparator IC1B produces a rising edge when the input exceeds VREF Low and comparator IC2A produces a rising edge when the in])ut exceeds VREFHIGH.Â·
The NOR gates, IC3A and IC3B, form a bistable latch whose Q output, when low, disables IC4. IC4, unless disabled, produces output pulses in response to falling edges at the IC1B comparator output. You set the width of these pulses by selecting the value of C3. The circuit can handle an input waveform containing 0 to 2 V amplitudes and 10-Hz to 10-kHz frequency components.