DIY Smart Electronic Candle using LDR

The DIY Smart Electronic Candle circuit operates by using a Light Dependent Resistor (LDR) to monitor ambient lighting conditions, acting as a light-to-voltage transducer. In bright environments, the resistance of the LDR decreases, altering the voltage divider network formed with the 1M resistor. Conversely, when darkness falls, the LDR's resistance increases significantly. This voltage shift is fed into the LM358 operational amplifier, which is configured to compare the sensor input against a reference threshold set by the 10K potentiometer. The potentiometer allows the user to precisely tune the ambient light level at which the circuit triggers. When the ambient light drops below the calibrated threshold, the LM358 output changes state, driving current through the 1K current-limiting resistor to illuminate the LEDs, creating the appearance of a glowing candle. The entire analog system is powered externally via a 12V adapter connected through a 12V female DC power jack, allowing steady operation without a dedicated microcontroller or software. By building this circuit on a perfboard and housing it within a card sheet enclosure, the components are securely mounted to form a compact, self-contained standalone analog device.