This circuit allows you to program, by temperaraly supplying logic high or low to the corasponding flip-flop inputs, a desired input (up to four inputs) in order to achive a positive 5 volt output. The LED's provide a conveniant way to show the 'program' or desired inputs. It is made of 4 Exclusive OR gates, 8 NAND gates, one 4 input AND gate (or 3 more NAND gates) and 4 LED's
This simple PLC can be used in many ways, from alarms to keypads to a simple brain for a robot, the only limit is your imaginaition.
These sensor circuits are probably the simplist detector circuits ever, all are compposed of transistors, resistors, and operaitional amplifiers. the layout is not critical, and they are easly powered by a 9 volt battery. The emmiter for all these circuits is a simple remote, like that of a VCR or a radio, even beter would be a IR laser from a CD player
This alarm is triggered when someone breaks a beam of IR between the emmiter and the detector, connected to the inputs of the circuit. There are two functions, silent (LED) and loud (piezo-electric buzzer), the alarm is deactivated by sending a voltage pulse through R (+) and G (-).
