Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Writing on dot matrix display with phototransistor pen

This technique is rather simple, but probably not many are using it. Kathy Yang shared his experiments where LED matrix is turned in to drawing board. Arduino UNO and 74LS138 ic’s take care of addressing each pixel on LED matrix. Phototransistor is used to read pixel coordinates and so the light corresponding LED. Whole trick lies upon scanning matrix lines with LEDs dimmed so it wouldn’t be looking as lit, but enough to be detected by phototransistor with comparator circuit. With a bit more polishing it could be really fun project to do with kids or even great learning kit to teach writing letters or numbers. Another use could be user interface, where one’s could change settings directly on display. Continue reading

The Coolest LED Sensor Piano Keyboard

Piano, one of the most popular musical instruments, no matter from the past and recently, have been set a high reputation for its on class. Most of the pianist has to go through a very tough examination, from the absolute beginner (Grade 1) to advanced (Grade 8). Honestly, it’s not an easy task, but you can quit whenever you want. By the way, for those who interested on the piano, but you don’t have the budget to purchase it, then this coolest sensor piano keyboard can be a very good option for you! Basically, the project utilizes an array of LEDs, which is working as light sensors. It helps to generate a musical tone and simulating a piano keyboard. For this project, the LEDs are being used as both emitters and sensors. Hence, you need to use 63 LEDs, where nine of the LEDs for each of the seven natural keys! For your information, when the key was pressed, the middle LED served as photodetector. It absorbs light from the other LEDs that reflected from the finger. An audio amplifier… Continue reading