Different range of temperature levels settings is available in the refrigerator; varying form low, normal up to high cooling. These ranges don’t provide a precise temperature. At times, we might need to set a limit of the temperature in the fridge for some reasons like to store certain types of foods or to get the exact accuracy of temperature we want. This circuit serves us right. The project entitled “Fridge Alert System circuit” is designed for the fridge.
With the help of this project, we can detect exact temperature of the fridge and use it to compare with the preset value we define in the project. Then if the measured temperature is found more than predefined temperature, the circuit sounds an alarm to alert people in the vicinity. In this project, we have set the temperature limit to 50C, so when the temperature of the fridge exceeds this value, the alarm is set.
Circuit Description of Fridge Alert System Circuit
Talking about the component list of this project, it just requires few numbers of components. As shown in the figure, Thermistor (TH1) which is used as temperature sensor, changes its resistance whenever there is change in the surrounding temperature. Thermistor is accompanied with IC1 CL7611 to monitor all the process of measurement and comparison of temperature inside the refrigerator. IC2 is used here to indicate the status of battery. LED1 which works as an indicator in this circuit glows to indicate that the temperature has increased more than the re-defined value.
PARTS LIST OF FRIDGE ALERT SYSTEM CIRCUIT
| Resistors (all ¼-watt, ± 5% Carbon) |
| R1, R2 = 4.7 MΩ
R3 = 2.2 MΩ R4 = 56 KΩ R5 = 12 KΩ R6 = 10 KΩ R7 = 270 Ω R8 = 390 Ω |
| Semiconductors |
| IC1 = CL7611 (CMOS operational amplifiers)
IC2 = 8211 T1 = 2TX300 LED1 = RED LED2 = Green |
Miscellaneous |
| SW1 = Push-to-on switch
TH1 = GL16 thermistor |