LED Fun And Light Painting With The PyMCU

November 5, 2012 by Jeremy Cook 2 Comments

Recently [Richard] at [pyMCU] was nice enough to send me one of their units to try out. As featured here before, this little board allows you to control physical things using your computer and the Python programming language. After evaluating it and making a LED blink, there were a couple other LED projects I wanted to try.

The first idea was to make a LED chaser. This was quite simple, using a little code and plugging in a few LEDs. From this, since you can make the LEDs chase each other, then in the right sequence it should be able to be used to display images using long-exposure photography. Be sure to check out the video after the break of this 10 LED chaser/light bar being assembled.

The results of this LED light bar experiment were really cool, writing some simple text and image with 10 LEDs. Considering the low component count, this is one of the simplest light bar builds that we’ve seen. Programming was simple as well, since the computer using Python does all the processing of the drawing as well as physically turning the LEDs on and off. Of course this setup isn’t without its limitations, having to be connected to a computer being the most obvious. Continue reading “LED Fun And Light Painting With The PyMCU” →

Thinking Cap Is Also Party Hat

November 5, 2012 by Eric Evenchick 10 Comments

The Thinking Cap is a piece of wearable signage that lets you display what’s on your mind. The hat uses a Teensy 2.0 connected to a Bluetooth radio to allow the wearer to update the message on the fly, letting the room know what their thinking at that instant.

This hack is based off of LPD8806 controlled LED strips, which are becoming very popular for adding lots of LEDs to anything. There are five strips that need to be controlled over SPI, but the Teensy only has one SPI peripheral.

This lead to the use of multiplexer to allow for controlling each strip individually. The hat uses an interesting and low cost scheme to multiplex five channels using two 744052 dual 4 channel multiplexors and a 7400 inverter.

The Teensy can receive messages using the Bluetooth serial port protocol. The 5 x 7 pixel characters are stored in a framebuffer, and shifted around the hat to create the animation.

The result is a bright message circling around the user’s head, which can be updated with a smartphone over Bluetooth. Check out a video demo of the hat after the break.

Continue reading “Thinking Cap Is Also Party Hat” →

Bluetooth Control For Your DSLR Or Just About Any Other IR Operated Device

October 30, 2012 by Mike Szczys 8 Comments

Just the other day we were reading a Reddit thread asking about how to control a television with a smartphone. The conversation started by talking about adding an IR LED to the phone. Then it was suggested that there should be standalone Bluetooth devices that convert commands to IR, and came around to the ideas that TV’s should ship with native Bluetooth hardware. We couldn’t agree more but we’re also not about to replace our TV just for this option. That’s why we were delighted to find this project waiting on our tip line. It’s a method of controlling a camera shutter from a smartphone using Bluetooth. But the technique will work for any device which uses an infrared remote control.

The video after the break shows two different devices controlling the camera shutter. As you can see in the diagram above, the iPhone is the master controller, connecting to a Bluetooth headset mounted on the camera. That headset was altered to feed the speaker connections into an IR LED pointed at the camera’s receiver. The iPhone plays an encoded audio track matching the IR remote command, resulting in the properly formatted message flashing on the LED. The watch doesn’t have the ability to playback audio, but it can send a message to the phone, which then plays the proper audio track through the headset.

Continue reading “Bluetooth Control For Your DSLR Or Just About Any Other IR Operated Device” →

Pumpkin Tetris Inspired By Our Own LED Jack-o-lantern

October 29, 2012 by Mike Szczys 12 Comments

The kids (or maybe their parents) are going to be lined up at [Nathan’s] front porch to get their turn at playing pumpkin Tetris. That’s right, he built a game of Tetris into a real pumpkin. We thought this looked quite familiar when we first saw it and indeed he was inspired by our own LED Matrix Pumpkin from two Halloweens ago. We love seeing derivative works and [Nathan] definitely make few great improvements to the process.

The matrix itself was wired in very much the same way we used, but he added an additional 58 LEDs to nearly double the size of the display. He used a paper grid and power drill to make room for the holes, but improved the visibility of the lights by sculpting square pixels in the skin of the fruit. But how does one control the game? The stem of the pumpkin is actually a joystick. One of the most innovative parts of the physical build was to use drywall anchors on the inside to mount the joystick hardware.

Don’t miss a demo video after the jump.

Continue reading “Pumpkin Tetris Inspired By Our Own LED Jack-o-lantern” →

Halloween Props: A Spooky Mirror

October 26, 2012 by Mike Szczys 5 Comments

This mirror will spook your guests with a variety of static and animated images. It includes a proximity sensor so the images will not appear until someone comes close enough to see themselves in the looking glass.

The electronic parts are quite easy to put together. There is a 32×32 RGB LED matrix mounted on the back of the mirror. It is driven by an IOIO board with some custom firmware written by [Ytai], the creator of that board who happens to live next door to [Alinke]. Where this starts to get interesting is when [Alinke] was working on the mirror to make the LEDs visible from the front. He used a razor knife to put hundreds of scratches in the varnish on the back. This lets just enough light through to see the LEDs, but keeps the mirrored surface reflective. See for yourself in the clip after the break.

The images are fed to the IOIO board by an Android device. We think this could have a lot of use after Halloween as a weather display or news ticker. Perhaps you could even feed it from your diy Android thermostat.

Continue reading “Halloween Props: A Spooky Mirror” →

Graphing The Efficiencies Of LED Light Strips

October 23, 2012 by Brian Benchoff 35 Comments

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.

TinyMatrix Derivative Uses PIC Instead Of AVR

October 22, 2012 by Mike Szczys 25 Comments

[Stu] has a teenage niece whose birthday is coming up and he wanted to give her something unique as a gift. He’s working on an LED matrix pendant that can display pixel graphics, play animations, and scroll messages.

He began the work after drawing inspiration from the TinyMatrix project. That clever design uses a DIP AVR chip soldered directly to the legs of a 5×7 LED matrix. It was powered by a coin cell with the power and ground wires acting as the necklace for the pendant. [Stu] is more comfortable developing using PIC chips, so he based his project on a 16F88. It will not run from a 3V source so he’s got a few issued to work out before the final design is finished.

One thing that’s quite interesting is his side project. After growing weary of hand coding the arrays for each frame of an animation he wrote a GUI in C# that let him design the image and output the code with a few clicks of the mouse.