This deluxe solar-powered light uses a battery and solar cells salvaged from a solar lamp with a four-cell battery (4.8 V nominal terminal voltage).
Efficient RGB LED Running Light Circuit
This circuit is adaptable to various DC voltages around its specified value, and it operates with low current consumption, approximately 20 mA. Consequently, the connected battery can sustain the circuit’s operation for up to five days. The setup incorporates an Atmel ATtiny microcontroller that directly drives a red, a green, and a blue LED through three port pins. To ensure safe LED operation, series resistors are included to limit the LED current. The microcontroller orchestrates the LEDs to create an appealing RGB running light effect. Additionally, the microcontroller is designed to automate the light, turning it on in darkness and off in light. The light sensor is ingeniously crafted from a solar cell salvaged from a malfunctioned solar lamp, a scenario where the battery failure is more common than that of the solar cells.
User-Friendly Project for Beginners
The power output of the solar cell is not a critical factor, as the microcontroller merely measures its output voltage utilizing its internal Analog-to-Digital (A/D) converter, connected to pin PB4. This project is particularly beginner-friendly, as a pre-programmed microcontroller is readily available from the Elektor Shop (order code 100581-41). The firmware was meticulously developed by the author using Flowcode. Both the source and hex files for the firmware can be downloaded for free from the project pages on the Elektor website at (www.elektor.com/100581).
Understanding Power Output and Its Significance
Power output, a crucial metric, represents the average rate of electric energy delivery within a specific metering interval. It is converted into an hourly rate of electric energy delivery, typically measured in kilowatt-hours (kWh) per hour. This value, often denoted in watts (W), signifies 1 joule (J) of energy delivered per second. For instance, a 40 W light bulb consumes 40 J of electrical energy every second to remain illuminated. Another context is the human body’s average power output during moderate exercise, which approximates 100 W. The power formula in watts is defined as P = W/t, where W represents the work done in a specific time interval t.