Graphing the efficiencies of LED light strips

After adding a few LED light strips above his desk, [Bogdan] was impressed with the results. They’re bright, look awesome, and exude a hacker aesthetic. Wanting to expand his LED strip installation, [Bogdan] decided to see if these inexpensive LED strips were actually less expensive in the long run than regular incandescent bulbs. The results were surprising, and we’ve got to give [Bogdan] a hand for his testing methodology.

[Bogdan]‘s test rig consists of a 15 cm piece of the LED strip left over from his previous installation. A Taos TSL2550 ambient light sensor is installed in a light-proof box along with the LED strip, and an AVR microcontroller writes the light level from the sensor and an ADC count (to get the current draw) of the rig every 6 hours.

After 700 hours, [Bogdan]‘s testing rig shows some surprising results. The light level has decreased about 12%, meaning the efficiency of his LED strip is decreasing. As for projecting when his LEDs will reach the end of their useful life, [Bogdan] predicts after 2200 hours (about 3 months), the LED strip will have dropped to 70% of their original brightness.

Comparing his LED strip against traditional incandescent bulbs – including the price paid for the LED strip, the cost of powering both the bulb and the strip, the cost of the power supply, and the time involved in changing out a LED strip, [Bogdan] calculates it will take 2800 hours before cheap LEDs are a cost-effective replacement for bulbs. With a useful life 600 hours less than that, [Bogdan] figures replacing your workshop lighting with LED strips – inexpensive though they are – isn’t an efficient way to spend money.

Of course with any study in the efficiency of new technology there are bound to be some conflating factors. We’re thinking [Bogdan] did a pretty good job at gauging the efficiency of LED strips here, but we would like to see some data from some more expensive and hopefully more efficient LED strips.

LED wand brings ergonomics to light painting

Quit struggling with hastily patched together electronics for your light painting images. Follow [Madox's] example and build a light painting wand designed with your hand in mind.

You wield it much like a sword, but the only damage it does is to the long-exposure camera pointed its way. The RGB LED strip is controlled by the guts of a tiny little wireless router, a TP-Link TL-WR703N. This lets [Madox] connect using an Android device to upload different images. It also lets you tweak the settings like adjusting the timing between columns to match your exposure settings. The custom handle design provides a home and mounting plan for everything involved. It was 3D printed at the Sydney Hackerspace.

This isn’t the first light painting device running Linux. We’ve actually seen the Raspberry Pi used in much the same way but that final project involved using an entire recumbent tricycle to move the colored lights.

One dimensional PONG is a great use for LED strips

[Jason] has had a five meter addressable RGB LED strip lying around for a while, and only recently came up with a good idea of what to use it for. He came up with One Dimensional PONG, and it looks like it’s a blast to play. Instead of moving a paddle up and down, [Jason]‘s 1D PONG game requires the players to stomp on a switch to send the ball back to the other player.

The LED strip [Jason] used has an SPI interface, but needed to be PWM clocked to a microcontroller to operate. After whipping up an Arduino library for his LED strip, [Jason] built an ATMega328-based controller board and a pair of seven segment display boards to keep track of the score. There’s a technical overview in another one of [Jason]‘s videos.

[Jason] will be taking his 1D PONG game to the Brighton Mini Maker Faire on September 8th. We’re sure his game will be very popular there, so if you see him, tell him Hackaday sent you.

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Light painting with the Raspi

The art of taking long exposure photographs with blinking RGB LEDs has improved greatly over the years, mostly due to the extremely easy to use Arduino and hundreds of tutorials on the web. If there’s one problem with light painting with a ‘duino, it’s that large, full color images take up a ton of storage space, much more than the flash memory on an Arduino can provide. Wanting fancier and more colorful light painted images, [Phil] over at Adafruit used a Raspberry Pi to make some very awesome light painted images.

Like any Adafruit tutorial that uses LEDs, the build begins with a digital RGB LED strip wired to the GPIO pins on the Raspi. After loading up the Adafruit educational Raspi Linux distro for hardware SPI support, the only thing left to do was writing a Python script to display images in the air.

[Phil] says vertical, hand-held LED bars are old hat, so he took a hula hoop and a few bits of PVC pipe, attached the LED strip, and put it on his bike. The results are really impressive – we’re loving the flames in the title pic – and considering the Raspi is a full-fledged computer, light paintings larger than what [Phil] made are very possible.

Back up the band with some RGB stage lights

Fresh off the 72-hour madness of the Red Bull Creation contest some of the folks a North Street Labs took on a stage lighting project. It’s for a local performing venue that just opened up, and despite the time crunch the team pulled off another great build.

Sixteen meters of LED strip make the electronics for the project a whole lot easier. The strips run up the center of a cabinets built as stand-alone columns which will end up at the back of the stage. Each cabinet has its own 5V 4A power supply (note the burnout issues they mention when using cheap eBay PSUs). Each column has its own Arduino Uno driving the LEDs, with an RS485 shield to connect back to a main Arduino Mega 2560 controller. It uses a PSX controller to switch between different lighting modes.

The seven towers boasting 688 LEDs isn’t all that’s shedding light on the show. There’s also about 300 feet of EL wire at work.

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RGB chandelier may not fly with the wife

We understand where [Craig] is coming from, leaving no stone unturned when looking for new electronic projects to occupy his time. He tried to convince his wife that they needed a light show to accompany dinner, and while she was skeptical he went ahead and built this remote control RGB chandelier anyway.

He recently purchased fifteen feet of RGB LED strip and has since been trying to use it in his projects. What’s interesting is that he didn’t make direct use of the strip. Just 10 of the LED packages were used. He desoldered and extended each wire leads and used one of the driver chips to address them all. The main body of the light fixture is a triangle, and out of each side two test tubes host one LED each. To diffuse the light [Craig] mixed up some resin and laced it with glitter. Once hardened the resin holds the LEDs firmly in place. The glass shade in the center of the fixture hides four more LEDs.

[Craig] uses a remote control from a Roku box to control the chandelier. An IR receiver is monitored by an Arduino which drives the LEDs accordingly. After the break you can see a demonstration of the completed project. Unfortunately it doesn’t provide as much light as they need. We’d suggest an upgrade along these lines.

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Simple light painting bar build

[SkyWodd] took the easy route when it came time to build this light painting bar. But he was still met with great success. Thanks to his well-documented work you should be able to throw this together for yourself in about an hour.

The idea here is to build a full-color display that will draw a picture in a long-exposure photograph. We’ve seen the concept used with 64 discrete RGB LEDs, but there’s almost no soldering to be done with this project. Instead, [SkyWodd] used an addressable RGB LED strip. It has 64 pixels, all taking commands via the SPI protocol. This helps keep the number of microcontroller connections to a minimum. He lashed the entire system onto a long hunk of wooden dowel and grabbed a camera.

You’ll need a DSLR as each image needs to have an exposure time approaching 10 seconds. One thing to note is that it may be best to leave the LED bar stationary and move the camera. If you use a tripod it should help keep the vibrations to a minimum.