Up/Down Pulse Separator
There are many circuits of direction detectors but either they are not quite reliable or they are bulky and the logic used is complicated. Here is a very simple circuit which serves both as direction (clock-wise/anticlock-wise) detector as well as an up/down counter. This circuit can find application in industries where winding and unwinding direction and turn count is to be known. Heart of the circuit is a dual D-type flip-flop CD4013 wherein clock and reset input pins are used to realise the necessary logic. When a disc is rotating clock-wise then FF2 will output negative going pulses, and when it is rotating in anti-clockwise direction then FF1 will output negative going pulses. These two outputs can be directly connected to the counter which can count up for FF2 and count down for FF1. If we desire to interface this circuit to any microprocessor, the same is also possible by using an S/R latch which has been realised here with the help of two NAND gates N3 and N4. Common output will always give the negative going pulses for both directions, whereas up/down output will be logically 1 for up counting and 0 for down counting as shown in the waveform. 