Make path detectors with NE555 ----- NE555 Loop Detector

Keywords: NE555, passage detection Author: Wang Xiaopeng This circuit is also a-type passage detector, suitable for inspection circuit of the circuit during installation and debugging and overhaul, easy to make, easy to make. 555 Integrated Circuit is connected to a lag comparing circuit. A and B are detected probes. Prior to detection, A and B are open, equivalent to open, at this time, 555 2 feet and 6 pins are high, 3 feet and 7 pin output low, so LED1 lights, LED2 does not illuminate. Therefore, when A, B receives both end points of the measured circuit, if the LED 2 emits light indicates a path between the A, B, otherwise the LED1 illuminates. In general, the two-point equivalent resistance ≤ 30Ω of the measured circuit is considered to be pathway, and <30ω is="" considered="" a="" blocking="" path.="" when="" a,="" b="" two="" probe="" contacts="" two="" points,="" if=""> 30 Ω, the 2 pin of 555 and 6 foot voltages are greater than 1/3 of the power supply voltage, the output state is unchanged, and the two LED luminescent states are also maintained. Change. If <30 ω,="" the="" 2="" pin="" voltage="" of="" 555="" is="" less="" than="" 1/3="" of="" the="" power="" supply="" voltage,="" so="" the="" 3="" foot="" output="" is="" flipped="" to="" high,="" so="" that="" the="" led2="" illuminates,="" and="" the="" inside="" is="" opened="" inside,="" so="" that="" the="" led1="" is="" not="" emitted.="">

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