2B-CLEVER RAIN ALARM
THE SPECIALITIES OF PROJECT
In market different types of rain alarms are available but they are not up to mark. We are giving a project which can give information about the rain and buzzer start giving alarm even with small amount of rain. It is a clever rain alarm due to different type of circuit.
TECHNICAL DESCRIPTION AND WORKING OF THE PROJECT
This project has been developed and tested by our readers and sent to the “T.V.Engineers Technical lab” for publication in the book. The spare parts and PCB of the projects published in the series of our book publication or available in the market. The information of project code is given in the first and last page of the books.
In this project they are 4 sensor with 4 resistances R1-R4 so there is no question of false alarm. The sensors R1-R4 with inverters Gate N1-N4 of IC CD40106 makes a sensor monitor section. The output of N1-N4 is given to the 4 Gates of Nand Gate 7.
In case of rain the inverter Gates N1-N4 gets low output through the four sensors. High output is available from the output side. When 4 input to the NAND Gate 7 are high then there is low output at the output Pin No.6. The output of NAND Gate 7 is given to the input of NAND Gate N5 and N6. When sensor give information about the rain at that moment the output of Gate N5 is connected to the ‘EXT’ output. The output of second inverter Gate No.6 is the Enable input to the NAND Gate N8 which works as a low frequency oscillator and Pieezo Buzzer is Modulated with this oscillations. With Preset VR1 the frequency of oscillation can be change from 10Hz to 200Hz. The output of buzzer is available only when 4 Sensors give indication. A single sensor can not do the job. 10Mili Amp 6V supply is used with CMOS and TTL ICs used in the circuits. As per construction guide fix the S1-S4 sensors on Epoxy Cement and keep them at proper place.
PRECAUTIONS WHILE MAKING THE PROJECT
- Use the shielded wire for connecting the sensors to main PCB.
- As per construction guide follow the instructions and use Epoxy Compound at the Terminal A & B of sensors.
Take proper precautions while soldering.