One of the questions that hobbyists ask over and over is how to select the value of a current limiting resistor for an LED. Usually the seat of the pants response is: “Subtract 2 V from the supply ...

144 LEDs total. Three sets of 48 in series connected in parallel. My problem is I don't know what value to use for R1. I'm thinking 600 ohm, but I really don't know how to calculate this. I'm making ...

In my previous column, we covered quite a lot of ground, starting with the first vacuum tube diodes, moving to their solid-state (semiconductor) descendants, and progressing to their light-emitting ...

A solar day lamp is a simple, inexpensive device for bringing “daylight” to dark interior spaces whenever the sun is shining. This article provides complete instructions for designing lamps using both ...