JUN12
Using LED as light sensor
Although this project doesn't have any practical use, it is pretty useful since it nicely describes the use of good old LED as a light sensor.
Therefore, LED can be used in two modes; as a photodiode and as LE diode because LE diode is nothing else than specifically doped diode to emit light, packed in transparent case. On the other hand, photodiode is a diode that is capable of converting light into either current or voltage, depending upon the mode of operation. As for this project, it was just necessary to measure voltage on LED and that's it! It is important to note that LED in this mode is sensitive to wavelengths equal to or shorter than the predominant wavelength it emits. The project is realised on Arduino board and source code is available for download.
Source: Zorink
JUN8
Solar powered audio amplifier
For these summer days out on the beach or even on a barbecue, you sure need good music. For music you usually need some power and power source is not easy to find on a beach. Either way, the Sun is up there so why not harvest some of it's massive energy to power a small audio amplifier and even mp3 player.
This project incorporates solar panels with DIY audio amplifier based on LM386 chip. The interesting part is that this device doesn't require any batteries, not even rechargeable ones. Instead it accumulates power into electrolytic capacitors for use, especially with those basses.
Source: pstretz
JUN2
A swing set that generates electricity
Well, you must agree with me that this swing set is no child's play. We have all seen the power generating shoes but this could be even more practical.
This project requires some serious mechanical assembling and a lot of parts but it can be built with good efficiency. Currently, as the author states, it produces only 5Volts but with some design changes it could easily produce a lot more. The generator used in this application is also a DIY version from Hugh Piggott's web site but a car's alternator can be used instead.
Source: Cleveland Motley
JUN1
Sea water battery
With only a few parts you can make a working battery with salt water as it's main ingredient.
This battery can produce 2-5mA at around 1V. Cathode and anode are made out of aluminium foil and graphite taken out from a pencil or old 1.5V battery. Electrolyte, which is actually a paper tissue soaked with salt water, is wound around a graphite rod which represent the anode. The other electrode is cathode and is made out of thin aluminium sheet. It all fits snugly in a film canister with two electrodes wires sticking out. This battery can well be used to power Joule Thief LED circuit.
Source: Coggz
MAY28
Current status of my mobile robot platform v1
I always had this idea of making my own GPS guided RC car. The hardware should not be very complicated but the software could get pretty messy.
After some planning I came up with the hardware design (my robotic platform) that has integrated: Atmega328P brain, HM55B digital compass, PING))) ultrasonic range finder, two MC33886 H-bridge controllers, voltage converters for all electronics on board, GPS receiver chip Venus634FLPx, some buttons and LEDs.
MAY27
Motion activated Super Mario thingy
We all remember good old Mario Bros game. Well, some of us still play it! John obviously can't get enough of it so he made a desk adornment in Mario Brothers mushroom candy tin in which he placed microcontroller, two LEDs, motion detector and a speaker.
After detecting the motion, mushroom device activates and starts playing Mario Bros game theme with LED blinking effect. Micocontroller used in this application is Attiny13A, motion detector is PIR sensor and it is all powered from USB port. What's interesting here is audio theme reproduction from microcontroller and that part is nicely described. Source code is available for download on project page.
Source: John
MAY25
Quick and funny solderless robots
Here is another version of bristle-bot but this time without heating up the soldering iron. With just two batteries, DC motor, few pieces of wire and brush head you can make a little robot that chaotically moves around.
This is not a very serious device and it has no specific purpose. Anyway, it would be very funny to watch few dozen of these crazy devices moving around and hitting each other in a condemned space.
Source: laxap
MAY21
Color detection with RGB LED
For color detection you usually need a color sensor. Here you will see that it is possible to detect a color by using only RGB LED and a photo-resistor.
The idea is that the amount of light reflected from an object is of maximum value when the object is the same color as the light source. That means that with RGB LED and a photo-resistor it is possible to detect a full color spectrum. Microchip PIC16F887 microcontroller is used in this project only because of that. If it is necessary to detect only one color than the microcontroller is not needed, only the circuit with fixed values. This is a very good explanation of a simple color sensor and it could be used in robotic sorting.
Source: Kyri
