Electronics Introduction

  If your   DHT11   is giving wrong readings (e.g., unrealistic humidity/temperature values,   NaN   errors, or erratic data), here are the most common causes and fixes: 1. Wiring Issues (Most Common Problem) Check: Pull-up resistor : A  4.7kΩ–10kΩ resistor  must connect the  DATA  line to  VCC  (DHT11 won't work reliably without it). Loose connections : Ensure wires are firmly plugged into the correct pins. Short circuits : Check if any wires are touching accidentally. Fix: Re-wire the circuit like this: text DHT11 VCC → 5V DHT11 GND → GND DHT11 DATA → Digital Pin (e.g., D2) 4.7kΩ resistor between DATA and VCC 2. Power Supply Problems Symptoms: Readings are  0 ,  -999 , or  randomly jump . Sensor gets warm (indicates a wiring mistake). Fix: Use a  stable 5V supply  (some 3.3V boards may not provide enough power). If using a long cable (>1m), add a  100nF capacitor  between  VCC and ...

  Creating a   smart home system   using a   Raspberry Pi 4B   is a popular and cost-effective solution due to its versatility, processing power, and connectivity options. Below is a step-by-step guide to designing and implementing a basic smart home system using the Raspberry Pi 4B. Key Features of a Raspberry Pi 4B-Based Smart Home System Centralized Control : Use the Raspberry Pi as a hub to control and monitor smart devices. Remote Access : Access and control devices from anywhere via the internet. Automation : Set up rules and schedules for devices to operate automatically. Integration : Connect with various sensors, actuators, and smart home protocols (e.g., Zigbee, Z-Wave, MQTT). User Interface : Provide a web-based or mobile app interface for easy control. Components Required Raspberry Pi 4B  (with power supply, microSD card, and case). Sensors : Temperature and humidity sensor (e.g., DHT22). Motion sensor (e.g., PIR sensor). Light sensor. Door/win...