LEDs are amazing things. As time marches on, they are being used in more and more lighting applications – everything from household bulbs to automotive headlights. But the push for smaller, cheaper, and brighter LEDs seems to have hit a snag for some of the less reputable manufactures.
Case in point, [bigclivedotcom] has been testing of some 100 Watt LEDs from eBay. When these LEDs work correctly, they put out a face-melting beam of light that you wouldn’t dare looking into (picture the scene from Raiders of the Lost Ark). They also have some unusual specs for an LED, like running on 30 Volts – and that’s a lot compared to the forward voltage of most LEDs at around 2.5 volts@20 mA.
So what gives? Well many of these high-wattage LEDs use a string of several LEDs in series. And as [bigclivedotcom] points out, this can be a real problem when a few of the LEDs begin to fail and act more like a low value resistor than a typical LED. In the videos after the break you can see [bigclivedotcom] test the LEDs to get a better look and what’s happening and why.
Continue reading “Why 100 Watt eBay LEDs Are Not Your Friends”
[Martin] recently purchased a Philips LivingColors lamp. It’s a commercial product that basically acts as mood lighting with the ability to change to many different colors. [Martin] was disappointed with the brightness of his off-the-shelf lamp. Rather than spend a few hundred dollars to purchase more lamps, he decided to modify the one he already had.
[Martin] started by removing the front cover of his lamp. He found that there were four bright LEDs inside. Two red, one green, and one blue. [Martin] soldered one wire to the driver of each LED. These wires then connected to four different N-channel MOSFET transistors on a piece of protoboard.
After hooking up his RIGOL oscilloscope, [Martin] was able to see that each LED was driven with a pulse width modulated signal. All he had to do was connect a simple non-addressable RGB LED strip and a power source to his new driver board. Now the lamp can control the LED strip along with the internal LEDs. This greatly extends the brightness of the lamp with minimal modifications to the commercial product. Be sure to check out the video below for a complete walk through. Continue reading “Increasing The Brightness Of A Philips LivingColors Lamp”
If you’ve ever tried to take nice photos of small objects in your home, you might have found that it can be more difficult than it seems. One way to really boost the quality of your photos is to get proper lighting with a good background. The problem is setting up a stage for photos can be expensive and time-consuming. [Spafouxx] shows that you don’t need to sink a lot of money or energy into a setup to get some high quality photos.
His lighting setup is very simple. Two wooden frames are built from scraps of wood. The frames stand upright and have two LED strips mounted horizontally. The LEDs face inwards toward the object of the photos. The light is diffused using ordinary parchment paper that you might use when baking.
The frames are angled to face the backdrop. In this case, the backdrop is made of a piece of A4 printer paper propped up against a plastic drink bottle. The paper is curved in such a way to prevent shadows. For being so simple, the example photo shows how clean the images look in the end.
Two years ago, [Matt] made a move away from his software hacks and into the physical world. He was part of a pilot program to provide mentorship to children as part of the Maker Education Initiative. This program gave him access to 3D printers, CNC machines, and laser cutters within the New York Hall of Science makerspace. [Matt] chose to build an illuminated notification cube for his first physical project. The idea being that smart phones have so many alerts, many of which are unimportant. His project would help him to visualize and categorize each alert to better understand its importance.
The brain of the system is a Raspberry Pi. [Matt] found a Python library that allowed him to directly control an RGB LED strip based on the LPD8806 chip. He wired the data pins directly to the Pi and used an old 5V cell phone charger to power the LEDs. The strip was cut into smaller strands. Each face of the cube would end up with three strands of two LEDs each, or six LEDs per side. [Matt] found a mount for the Pi on Thingiverse and used a 3D printer to bring it into existence. The sides were made of frosted laser cut acrylic. The frosted look helps to diffuse the light from the LEDs.
Over time [Matt] found that the cube wasn’t as useful as he originally thought it would be. He just didn’t have enough alerts to justify the need. He ended up reprogramming the Pi to pull weather information instead, making use of the exact same hardware for another, more useful purpose.
If there’s one game that deserves to be overengineered with hundreds of LEDs, sensors, and electronic modules, it’s beer pong. [Jeff] has created the most ostentatious beer pong table we’ve ever seen. It’s just shy of playing beer pong on a single gigantic LED display, and boy, does it look good.
The table includes a 32×12 grid of LEDs in the center of the table, with 10 pods for Solo cups at each end of the table. These pods have 20 RGB LEDs each and infrared sensors that react to a cup being placed on them. The outer edge of the table has 12 LED rings for spectators, giving this beer pong table 1122 total LEDs on 608 individual channels.
With that many LEDs, how to drive all of them becomes very important. There’s a very large custom board in this table with a PIC24 microcontroller, TLC5955 PWM drivers, and enough IDC headers to seriously reconsider using IDC headers.
Put enough LEDs on something and it’s bound to be cool, but [Jeff] is taking this several steps further with some interesting features. There’s a Bluetooth module for controlling the table with a phone, a VU meter to give the table some audio-based visualizations, and air baths for cleaning the balls; drop a ball down the ‘in’ hole, and it pops out the ‘out’ hole, good as new. If you’ve ever wondered how much effort can go into building a beer pong table, there you go. Video below.
Continue reading “Overengineering Beer Pong”
[Esai] wanted to build an electronic clock from scratch. A noble quest, but ordinary seven-segment displays are just that – incredibly ordinary. Instead of a few displays that can be bought from the usual retailers for a dollar a piece, [Esai] made his own four digit, seven-segment display on some perfboard.
Before soldering 58 SMD LEDs to a small rectangle of perfboard, [Esai] traced out each segment with a marker. Two LEDs make up each segment, and they’re all connected to a breadboard-friendly pin header with 30 gauge wire.
Each segment is connected as a single column in the LED matrix, and each digit is a row. It’s a simple design, but there aren’t any resistors on this board. Hopefully [Esai] will be using a proper LED driver with this display; you really don’t want LEDs to burn out twice a day at 1:11.
If you want to proclaim to the world that you’re a geek, one good way to go about it is to wear a wristwatch that displays the time in binary. [Jordan] designs embedded systems, and he figured that by building this watch he could not only build up his geek cred but also learn a thing or two about working with PIC microcontrollers for low power applications. It seems he was able to accomplish both of these goals.
The wristwatch runs off of a PIC18F24J11 microcontroller. This chip seemed ideal because it included a built in real-time clock and calendar source. It also included enough pins to drive the LEDs without the need of a shift register. The icing on the cake was a deep sleep mode that would decrease the overall power consumption.
The watch contains three sets of LEDs to display the information. Two green LEDs get toggled back and forth to indicate to the user whether the time or date is being displayed. When the time is being displayed, the green LED toggles on or off each second. The top row of red LEDs displays either the current hour or month. The bottom row of blue LEDs displays the minutes or the day of the month. The PCB silk screen has labels that help the user identify what each LED is for.
The unit is controlled via two push buttons. The three primary modes are time, date, and seconds. “Seconds” mode changes the bottom row of LEDs so they update to show how many seconds have passed in the current minute. [Jordan] went so far as to include a sort of animation in between modes. Whenever the mode is changed, the LED values shift in from the left. Small things like that really take this project a step further than most.
The board includes a header to make it easy to reprogram the PIC. [Jordan] seized an opportunity to make extra use out of this header. By placing the header at the top of the board, and an extra header at the bottom, he was able to use a ribbon cable as the watch band. The cable is not used in normal operation, but it adds that extra bit of geekiness to an already geeky project.
[Jordan] got such a big response from the Internet community about this project that he started selling them online. The only problem is he sold out immediately. Luckily for us, he released all of the source code and schematics on GitHub so we can make our own.