Kieth’s Blog has many ideas on refurbishing and creating electronic gadgets, Mechanical and DIY Techniques.
Keith Neufeld – Electronics Blog
LED Calculator with Rotary Quadrature Encoder for Target System Voltage Selection, Arduino, Robotics, PCB Layout Tips, Introduction to Circuits, LED Clock.
Transistor-Based Variable Current Drive for LED Calculator
“The idea is to expand on a simple LED tester by allowing the user to plug in an LED, dial in the LED brightness, and then read information on an LCD showing the LED voltage drop, the current current, and the value of current-limiting resistor to use in a target circuit. “