Fig 1. This voltage regulator circuit (a) uses green LEDs as both the stabilization elements and as the voltage indicators at the front-panel switch (b). Fig 2. The addition of resistor R4 to the ...

This circuit can be used to test up to three LEDs at once, connected in series. You can easily increase that number by using a higher supply voltage. If you do so, you should allow 2.7 V for each ...

High-power LEDs promise a growing number of advantages, including lower long-term cost and longer life, over both incandescent light bulbs for interior For the PDF version of this article, click here.