This budget-priced color Wi-Fi bulb offers ample flexibility—for both color and white light—at a great price. TP-Link has given its Kasa Smart Wi-Fi light bulb line a significant upgrade. The old LB ...

A 6-V battery powers a circuit with parallel branches on a board. Several wires and light bulbs plug into the board to make various series and parallel circuits. The brightness of the bulbs changes ...