We have worked on LED matrix for so many times, but mostly for text scrolling, so how about make some animations on it? But we are too lazy to make the animation patterns to the C header file in an array of bytes. We finally finished one tool may be useful for all led matrix lovers!
The gif2led project is written in Ruby, required Rmagick library for gif manipulation. It is mainly designed for 8 or less columns matrix, for instance 8x8 matrix, 10x8 matrix, 5x7 matrix etc. It output an pattern header file with a 2D array frame by frame from an animated gif input. We only tested with AVR-gcc, but it should be useful for other MCUs too. You can find more information on the gif2led project page, http://labs.bitartist.org/gif2led/
Let start with our demonstration, the project is called LED Egg, it is based on a 10x10 matrix (but we only use 10x8 in our case) with an Egg case to hold the circuit board.
To prepare the animated gif, we use macromedia Flash, and here is the screenshot:
Noted that the frame 0 (marked as CAL above) is a special frame, which used for calibration. When used with gif2led tool, the frame 0 is the pattern of your led matrix with all led ON.
and then export the movie to an animated gif:
Then simply run the following command, we can obtain the 2D array header file:
Now, we have to prepare the circuit part, we use AVR tiny13 together with 4017, please refer to the circuit diagram<here>. 4017 is used as a row counter, and such that we can only use 1 pin for row shifting. The remaining 4 IOs of the tiny13 would use for column output, we are using 10x8 matrix this time, so we assume the pattern is symteric to save pins, so 1 I/O drive 2 columns in our case. The circuit showed below:
So Lets add an egg case, the egg is made from pu foam plastic, it is used for Easter decoration.
Video demonstration:
Close look on the LED pattern:
To download the gif2led tool, AVR source codes, and flash template, please find in the following links:
Electroluminescent(EL) technology always uses in the backlit of small LCD. From wikipedia:
Electroluminescence is the result of radiative recombination of electrons and holes in a material (usually a semiconductor). The excited electrons release their energy as photons - light
Anyway, it is good for lighting.
I got the EL panel in a local store which should be powder phosphor-based electroluminescent panel. It is a 3.5" x 4.6" white light panel.
It included an adapter for converting 12VDC to AC for the EL panel.
Let's see how we can make use of this EL lamp.
1. Use for slice viewing
2. Put a Post-It on it, and you can see a growing Post-It in the dark.
3. For home lighting, illuminate your Toys.
4. A BackLit Photo Frame
Step 1 - To make a DIY backLit photo frame, you can get a large photo frame in store or you can make one yourself. Here we are:
Step 2 - Glue the panel in the back cover of the photo frame. You can see there is about 1.5 inch space between the photo glass panel and the back cover. We like to have some distances apart the EL panel and the glass to diffuse the strong illumination of the EL.
Step 3 - Power Up.
It looks alot better on my desk, sorry for my poor photo skill. Let's see the photo frame in action in the below youtube video. Enjoy It.
Anyone who want to get this EL panel (3.5" x 4.6"), We can order it for you. It is only US$15, and $5 for shipping to US and Canada. For payment, We use paypal. Please contact us: order@bitartist.org
Hydrogen fuel cell is the next green source of energy, by breaking down water (H2o) into hydrogen (H2) and oxygen (O2), the hydrogen can be used for energy generation afterward. It is still a long way to go in normal usage, but how well is the technology now?
Horizon Full Cell Technology introduced a Toy Car using their fuel cell technology. You can buy a toy car in affordable price to taste this bleeding edge technology.
After studying how to make a simple solar charger, I decide to make a fast prototype to test. I got one solar panel a long time ago, the ratings of this solar panel is unknown. The solar panel will output different voltage and current under different lighting condition, so we have to measure it before use. I measured this solar panel would output maximum 3V under bright sunlight, and output 2V under my table lamp.
Everyone got a table lamp when working in front of the computer, and the light condition will remain considerably constant when compare to the outdoor sunlight condition. It would be easy to make one simple table lamp charger.
The above diagram is my setup, I used the schottky diode (IN5819) to prevent back current flow to solar panel when the lamp is off. The diode is placed between the solar panel and the the battery holder with two AAA batteries loaded. When charging, I measured the forward voltage across the diode is 0.14V which is small when compare to a normal diode.
Initially, the voltage across 2 batteries are 1.7V, after a while the voltage is 1.81V, so it is charging right now. The charge current measured is only 0.12mA.
The current is too small, and not so sure how long it will charge up to 2V:)
It is one of my favorite video from http://www.newscientist.com/, it talks about the robot research around the world that using the movement technique from different kinds of animal. It is really amazing to see all these robots moving. It is really Real.
