The thermistor is used as the temperature alarm of the sensitive component. When the temperature contacted by the metal probe passes through the sensor to the switch, if the temperature exceeds the predetermined value, the switch at this time is turned on, and the alarm is connected to the alarm, and the sound is sounded at this time. The alarm device can make different sounds by changing the connection of some components. In order to increase the practical effect, an indicating circuit composed of a common anode two-color luminous tube is additionally added. When the circuit is not alarming, it is green, but when it is alarming, it is red and green alternately.
At present, the living standards of our people have improved, and some electrical products are reaching thousands of households. According to statistics, there are currently about 1.3 billion people in China, and almost every family has used boiling water tools like hot ones. What followed was an accident that was caused by improper use or use while forgetting. If the system is used in practice, it can effectively curb such accidents. Therefore, if the actual product is put on the market, it will have a large market space and broad development prospects. This product can emit different alarm sounds when connecting some connections in different ways.
This product overcomes the shortcomings of the popular alarms, has low cost, and has greater practicability and novelty. The main innovations and application prospects are as follows: high sensitivity, high stability, and timely alarm.
The system has high sensitivity and high stability, thanks to the system has a good sensor. But it still has certain flaws, and it has its own limitations. If a better sensor can be applied to the product, the product will have a broader development prospect.
Temperature alarm production process
Temperature alarm circuit design scheme 1 working principle design scheme 1 of the circuit diagram shown in Figure 1:
The main circuit of the temperature alarm consists of NTC temperature measuring resistor, adjustable temperature potentiometer, low frequency oscillator and audio oscillator. The working principle is as follows:
The temperature value is set by the potentiometer. When the temperature rises, the resistance value of the temperature measuring resistor NTC decreases, reaching the CD4011 input high-level threshold, causing the low-frequency oscillator to work, modulating the audio oscillator, and amplifying through the triode, by the alarm The device sounds an alarm.