555 temperature limit controller circuit with heating acoustics alarming

Published:2011/6/3 9:03:00 Author:nelly | Keyword: temperature limit controller, heating acoustics alarming | From:SeekIC

This temperature limit control circuit is made of hypotension rectifier, voltage-stabilizing circuit, temperature measurement comparator, heater and acoustics alarming circuit. It is mainly used in occasion which need higher controlled temperature, such asfluid infusion, blood transfusion heating control, incubator and so on. Its circuit is shown in the figure 12-41. The process of temperature control is shown: when the ambient temperature is lower than the limited temperature, the resistance value of thermal resistor RT is greater, the output of comparator IC1-a is high level, the output of follower IC1-b is high level too, VT1, VT2 are turned on, the heater obtains electricity and is heated; at the same time, the heating indicator light LED1 turns on. When the ambient temperature is higher than the limited temperature, the resistance value of RT is decreased, IC1-a outputs low level, IC1-b outputs low level too, then the constant temperature indicator light LED2 turns on, at the same time, VT1, VT2 cut off, the heating is stopped.



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