[mircemk] built a slick-looking LED tester with a couple handy functions built in. Not only can one select a target current to put through an LED, but by providing a target voltage, the system will ...

The basic circuit illuminates up to ten LEDs in sequence, following the rhythm of music or speech picked-up by a small microphone. The expanded version can drive up to ten strips, formed by up to five ...

Light-emitting diodes (LEDs) are often used with a voltage source from a power-supply output voltage. The output voltage increases until the current through the LEDs reaches the value of the ...

To measure a zener diode’s breakdown voltage, you need a dc voltage source whose voltage exceeds that of the zener voltage. In Figure 1, resistor R SER provides voltage drop between V IN and V ZEN. In ...

Lighting a string of LEDs at a constant brightness requires driving it with a regulated current. A boost converter is commonly used to step up the voltage to a level high enough to bias the LEDs on ...

Microcontroller port pins can typically be driven either high or low, or else be put into an "input" or high-impedance state. This circuit uses the three states to drive two separate LEDs with one ...

[Eric Wasatonic] had a box of SWB2433 transistors that he had very little information about. In order to discover their properties, he fired up his curve tracer to compare these transistors with more ...