555-channel temperature test circuits

  
Circuit shown in Figure, when used in multi-temperature test, switch the thermocouple corresponding channel. 555 brightest are at the core monostable delay circuit, such as Cli
555-channel temperature test circuits - schematic

ck AN, because the 2-pin was low, the IC1 set, was 3 feet high, J1 pull, the thermocouple channel ON. Meanwhile, C1 through R1 charging it, when the charging voltage reaches the threshold level 6 feet 2/3Vdd, the 555 reset pin 3 referred to the low level, in turn triggering a second stage IC2, the IC2 set, turns ON Road thermocouple, and then click the trigger. If J1 is closed, the cycle can be monitored. Each level of the delay time (ie measuring time) td 1.1R1C1, icon parameter corresponding delay is about 1 second. LED1 ~ LEDn LEDs also turn lights, as a monitoring indicator. Figure a circuit when power-up, there are a few pieces of LED light tubes flicker at the same time, therefore, to improve the circuit shown in Figure b. After accessing R, C network, boot, since C voltage can not change suddenly, so that the reset terminal pin 4 is forced reset state, 3 feet showed low output, as the charging capacitor C, so that was 4 feet high level, IC trigger timing in a wait state levels, have improved the accuracy of the test.




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