Kettle automatic alarm circuit

Published:2011/5/8 19:57:00 Author:Christina | Keyword: Kettle, automatic alarm | From:SeekIC

When you boil water by the home gas stove, it often spills off the flame by the boiling water, and this leads to gas leak. This is a waste of energy and would cause serious accidents. Use the Kettle automatic alarm which is made by the PTC thermistor, you can prevent the accidents. 1 circuit principle The core of this kettle automatic alarm circuit is composed of the NAND IC block and the PTC thermistor, the circuit principle is as shown in figure 1. Before the water temperature meets the default value, RT's resistance is small, IC's input voltage is lower than the threshold voltage, B will not alarm. When the water temperature meets the boiling point, RT's resistance increase rapidly and higher than the threshold voltage, after 30 seconds, IC outputs the voice signal and B issues the alarm. Figure 1. Kettle automatic alarm circuit 2 Select the main components The Kettle automatic alarm circuit's RT temperature probe uses the PTC thermistor, the room temperature resistance is ≤500Ω, the standard resistance - temperature characteristic curve is as shown in figure 2.8.2. Buzzer B uses the Ф27mm. Figure 2. The standard resistance - temperature characteristic curve 3 Installation and Commissioning When you use it, put the temperature sensor end into the kettle, the alarm installed in the place where is easy to hear the alarm sound, and notic the moisture.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/Kettle_automatic_alarm_circuit.html

Print this Page | Comments | Reading(3)