Drum light trigger that uses leds, a NE555 timer and a piezo transducer

Davide Gironi writes: This circuit is a Drum Light Trigger. It uses a piezo transducer that reacts to drum vibration, and a NE555 timer to setup the light time. There are two trimmer pot, one to setup the sensibility of the vibration, the other to set how long the LED light will be active. This […]

Simple LED driver/constant-current source 20 mA

Another Instructable by Jan Henrik,  a constant-current source which gives 20mA at the output.  He writes: It is a circuit, which limits the current to 20mA, what allows us to drive any normal led, without calculating a resistor, you can just plug the led in and see it emitting light… Also this allows us to test […]

BlueMatrix – Bluetooth controlled LED matrix

Luca Dentella has published his latest project: BlueMatrix. It’s a portable LED matrix display based on Arduino Uno, powered by a Lipo battery and connected via Bluetooth to a personal computer or an Android smartphone. I’ve also developed the controlling app for Android, available on Google’s PlayStore. All the schematics, source files, inkscape files for […]

chipKIT Project 5: Digital stopwatch on seven segment LED display

Raj of Embedded Lab has a series of chipKIT tutorials.  This 5th project will show you how to build a digital stopwatch  on seven segment LED display with the chipKIT Uno32: In this project, we will use the chipKIT Uno32 board to build a digital stopwatch capable of timing minutes, seconds, and 1/10th of seconds, and with a […]

A quick and dirty methods to drive 7-segment LED displays directly with a microcontroller and no external components

Scott Harden writes: I came across the need for a quick and dirty display to show a 4 digit number from a microcontroller. The right way to do this would be to use a microcontroller in combination with a collection of transistors and current limiting resistors, or even a dedicated 7-segment LED driver IC. The […]

LED ring based illumination for American optical microscopes

TomKeddie writes: Based on a recommendation in these forums I bought an American Optical 570 stereo microscope on ebay some time back. I added the illumination shown below, I thought it might be useful to others. I cut 3 pieces from a right angle piece of aluminium section, coated them in heatshrink, attached them to […]

SquareWear Mini chainable color LED matrix and animation design tool

Ray Wang writes about his recently completed project, the SquareWear Mini with All-New Chainable Color LED Matrix, and an Interactive Animation Design Tool. The goal is to make standalone programmable color display gadgets. The LED matrix is chainable and can be seamlessly extended in both X and Y directions. The SquareWear Mini is essentially an […]

Valentine LED chaser

As Valentines day is fast approaching, many are thinking of a wonderful present to their love ones. Tom built this heart-shaped LED chaser and wrote a post on his blog detailing it’s assembly: The object of your desire will not be able to resist a heart-shaped LED chaser, lovingly hand-crafted on perfboard with a CD4017B decade counter […]

DIY 3W constant current LED driver

Dilshan Jayakody wrote a post on his blog about his 3W constant current LED driver: This is quick post about 3W constant current LED driver which I was design to combine with some homemade furniture piece. The main components of this system is LM311 voltage comparator and IRF9640 P-Channel MOSFET. This module is design to drive maximum of […]