EEG driven Magic Ears

This is a project designed by the people of Cornell University which reads user’s excitement degree and controls the ears to show different gestures. It uses electroencephalography (EEG) with the AVR microcontroller. The EEG sensor comprises of both low pass as well as high pass filter along with amplifiers. The design is built around a ATMEGA controller along with a pair of EEG electrodes and some basic analog electronics. The amplifier is built around a AD620 amplifier chip which has a very high input impedance and hence is an ideal choice for EEC detection.  The analog circuit is mainly used to filter the alpha band of the brain wave and the microcontroller controls the two motor based on the level of the EEG signal. However the problem that arise is… Continue reading

Easy to build proximity sensor

Whoa! This project seems really interesting and many of you will agree after reading the post. All the people are familiar with ultrasonic sensor. There are some cheaply available sensor that comes in less than 10$ while some are costly but provides greater range. Why buy a readymade sensor, when you can make your own at a low cost and a considerable range. In an ultrasonic sensor, a short ultrasonic wave is shot out which gets reflected back from the object, and the time after it’s received is noted down. Since we have the time and the speed of ultrasonic we can easily find the distance. In the design, there is a separate transducer for transmitter and receiver to avoid complexity. He used a 24KHZ transducer which are readymade and… Continue reading

Wind Indicator

Every other person has some fantasy towards weather. They really like to be updated about the weather very frequently. The author of the project was one of the same kind of person. The author of the project designed a LED based Wind indicator which displays the wind direction, its force and a prediction for the next day. Since the project is still in the developing mode, the data which the wind indicator has to be connected to the PC using a USB to serial interface. If your PC has a serial port unlike a laptop, you can directly hook up a serial cable instead of using the converter. For the project all you need are LED’s, resistors, buttons, screw terminals, Atmega, its ISP programmer and python v2.6. The project has… Continue reading

Smart AVR based color sensor

avr based rgb color sensor

If you ever used image editing software, you probably tried color picker tool. It allows pointing to any place (pixel) of image or digital photo and it returns its RGB value. This is handy way of determining digital color value. Well this is easy when you have image stored in computer. But what about real world objects. How can we pick the color? You can get RGB values by taking photos and then using software packages like GIMP to find its RGB value. Or you can try building a color sensor circuit that would allow pick colors by putting it close to color object and pick its color. Sounds cool, isn’t it? As matter of fact the science behind such device is simple, and everyone can build it with few… Continue reading

One button PS/2 keyboard on AVR microcontroller

It is practically hard to find a keyboard with PS/2 interfaces. All is taken by USB. Anyway owners of older computers still use them (including myself). I see no problem with that. It is reliable and works with no problem. It happens that some older systems aren’t so much robust with USB keyboards. Joonas has discovered that his newest keyboard didn’t work using PS/2 to USB adapter. Problem was that motherboard needs a spacebar key click in order to power up. Instead of looking for new keyboard he decided to solve this problem with DIY minimal keyboard built around Attiny2313. Generating keystroke commands and sending them using PS/2 protocol isn’t that complex and small micro can deal with this. Especially when single key press is needed. AVR generates spacebar command… Continue reading

Building precise temperature meter

Temperature sensor devices are common around us. They differ in their precision and measuring method. What interests us is MCU based temperature meter that gives reliable readings. For instance cheap room thermometers aren’t that precise. They can be have error about 1 degree. This might not be acceptable in some situations. So what to do if you want really precise measurements? Scott Harden has been working on new projects where he wants to control crystal oven with high precision. As sensor he chooses LM335 linear temperature sensor. In order to get high resolution, he built LM324 op-amp based based circuit which expands smaller temperature interval to Atmega8 microcontroller ADC range and thus he gets about 0.01F resolution. Since he uses cheap and available components like LM324 operation amplifier, this project… Continue reading