The system is built around the PIC16F877A microcontroller, which serves as the central processing unit. To provide a stable clock signal, it is equipped with an external oscillator circuit consisting of a crystal (X1) and two 22pF capacitors (C1 and C2). A 10k$\Omega$ resistor (R2) is tied to the MCLR pin as a pull-up to ensure stable operation and prevent accidental resets. For user interface and digital sensing, the microcontroller interfaces with an LM016L (16 \times 2) LCD—featuring a 10k$\Omega$ potentiometer (RV1) for contrast adjustment—and a DHT11 digital humidity and temperature sensor, which utilizes a 5k$\Omega$ pull-up resistor (R1) on its data line. ​In parallel to the digital monitoring, the circuit includes an independent analog signal processing stage. An analog temperature sensor (like the LM35) feeds its voltage signal into an LM324 quad operational amplifier array configured as three distinct voltage comparators. The precise threshold reference voltages for these comparators are set using three potentiometers (RV2, RV3, RV4) alongside a network of static resistors (68k\Omega and 1k\Omega). The outputs of these analog comparators are routed into a 4532 8-to-3 priority encoder, which converts the active comparator levels into a binary code. This digital code drives the bases of three 2N2222 NPN transistors through 2k\Omega current-limiting resistors (R7, R5, R6). Operating as electronic switches, these transistors control three indicator LEDs (Red, Green, and Blue), each protected by specialized current-limiting resistors (510\Omega, 470\Omega, and 390\Omega respectively).

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