Ten Road temperature itinerant detecting circuit 555 CD4069 CH208

  
As shown in Fig ten temperature detection circuit circuit. The detection circuit by the temperature sensor, V/F converter circuit, an oscillator, circuit testing program contro
Ten Road temperature itinerant detecting circuit 555 CD4069 CH208 - schematic

l, alarm, decoded and displayed circuit. Temperature sensor 3AX31, and diode-connected form. When the ambient temperature changes, the radio - sets and resistance k linearly with temperature changes. Oscillator consists of IC1 (555) and rce, R1, C1 and other components, the oscillation frequency of f 1.44/(R1 + 2rce) C1, it rce changes linearly with temperature, then f accordingly varies in proportion to, in order to achieve temperature/frequency conversion. If the detected 10 points, need 10 such temperature/frequency converter head. Circuit IC2 use hex inverter CD4069, where F1, F2, F3 composed of 0.2Hz trigger pulse generator, which sends a pulse count CP every 5 seconds to count circuit IC3. IC3 decimal counter/pulse distributor CD4017, under CP effect, its ten output terminal Q0 ~ Q9 successively appear high pulse. Corresponding analog electronic switch K1 ~ K10 are sequentially turned on. IC4 using analog switches CD4066, K1 ~ K10 frequency signal outputted sequentially fed into the phase locked loop circuit having an audio decoder IC5 (567) pin (IC5 wherein the center frequency is f0 1/1.1RwC4, circuit C5 adjustable given locking bandwidth), when the temperature exceeds a certain limit the scope of the road, and with a preset center frequency f0 are the same, IC5 output low (since feet), making BG conduction, the relay J pull the trigger alarm circuit, alarm anthracene ring. At the same time, Q0 ~ Q9 high signal output of IC3 in turn fed IC6 (CH208) decoding display circuit, after IC6 decode output signal corresponding fields, drive common cathode LED digital tube work, it appears the corresponding point over-temperature field. The detection circuit is adapted to units, and other train axle temperature detection occasions.




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