A-Z Of Electronics – Capacitors


[Jeri Ellsworth] recently released another video in her “A-Z of Electronics” series – this time Capacitors are the subject. As a penance for my boneheaded AC Capacitor suggestion yesterday (I swear it was lack of sleep talking), [Caleb] suggested that I be the one to write this article. Since I’m not an electrical engineer (I majored in Comp Sci), I enjoy watching these videos, and I share them with individuals who are new to electronics. [Jeri] always presents the subject matter in a clear and concise manner, so the subjects do not seem daunting or intimidating.

She briefly discusses the early development of capacitors, including Leyden Jars, then focuses on modern capacitors and their usage. She covers wiring capacitors in circuits, demonstrating the difference between series and parallel configurations, as well as how electrode distance affects capacitance.

If you have a spare minute, be sure to check out her current video as well as those she has previously released.


[Andrew] is showing off his latest creation, an LED matrix clock, which he is calling “DOTKLOK”. The clock is powered by an atmega328 micro controller with a real time clock module keeping the time. The display is made out of a grid of 8×8 LED matrices giving it a resolution of 24×16, and is all housed in an attractive acrylic housing.

The clock animations are inspired by classic video games such as Pong, Tetris, Pacman, and Space Invaders. Since the software is open, it is easy to jump into the Arduino source and add or modify animations to suit your taste, or even use the clock as a custom display for non clock related applications.

Available as a kit or fully assembled if youre needing a gift for that special nerdy someone. If you would like to go it alone, source, schematics, pcb, and enclosure files are available along with a bill of materials.

Join us after the break to see a short video of this fun clock in action

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Screamer Doll Prank Toy


While it is only the middle of February, it might be a good time to start thinking about your plans for April Fool’s day. [Dino’s] Screamer Doll is his submission to the upcoming 555 Contest.  This fun little circuit can be used to easily annoy your cube or house mates and is perfect for all of the April Fool’s day pranksters out there. He fit all the components into a small plastic toy, replacing the eyes and mouth of the doll with three photo cells, and swapping the nose out for a bright LED. When light hits the photo cells, a loud high-pitched squeal is emitted, and the LED blinks furiously until the light source is removed. Shielding the device from light will cause both the sound and LED to slow down, but the brightness of the LED ensures that the toy still makes noise when covered.

It would be great to see a version of this project that is completely silent in the dark, allowing it to be hidden at night, greeting its victims come morning.

If you want to see video of the device in action, read on – just be sure to keep your speaker volume at a reasonable level!

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Learn To Debug Msp430 Chips Using IAR

If you haven’t done any debugging with microcontroller programs [Kphlight] posted a follow-along guide for debugging MSP430 chips. You can see above that he’s using the TI Launchpad and has chosen the free (but code limited) IAR Embedded Workbench that is one of the IDE’s that TI provides for the kit. The example builds a Pomodoro timer with just five LEDs and one resistor. You’ll flash the code to the chip, step through each line of the firmware, and learn how to manipulate register data during code execution.

It’s a great primer for the uninitiated, and we’d love to see one using open-source tools like DDD and GDB. If you do write one, don’t forget to send us a tip about it. If you want to give open source a try with this hardware check out our own tutorial.

Nimbus, The Wall-following Robot


[Johannes] sent in the latest iteration of an ongoing project – Nimbus, the wall-follwing robot. Originally operating on a cardboard frame, the robot has undergone several revisions as you can see by reading through his blog. Nimbus started out as a simple, Arduino-powered robot, but the project has progressed nicely over time. The last revision simply avoided walls, using a Sharp IR proximity sensor to detect, then avoid obstacles. The most recent model sports a nice polycarbonate frame as well as two additional IR proximity sensors, allowing Nimbus to navigate quite well, following walls and avoiding obstacles with ease. It does get caught up from time to time on carpets and wires, but overall Nimbus is a great little robot. [Johannes] even added a small RGB status LED for the bottom of the bot, communicating its navigation status to the operator at all times. This is done by flashing various colors when objects have been discovered or have moved out of sight – it’s a really novel addition.

Keep reading for a video of Nimbus navigating his way around, and don’t forget to check out the Nimbus photo stream.

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WWII’s Top Cryptography Comes To A Child’s Toy

This toy has some upgraded internals that turn it into an Enigma machine. We absolutely love the idea, as it takes a toy that your child may have grown out of, and uses it to provide teachable moments dealing with both history and mathematics. But who are we kidding? We want to make one just because it’s a fun project.

[Sketch] grabbed this toy from a thrift store because it has a full keyboard that he can use to make his own machine. It’s powered by an Arduino, with a four-line character LCD display taking the place of the original. His post covers the methods he used to figure out the keyboard wiring, and also contains a cursory overview of how the Enigma Machine functions. See a video of the finished project after the break.

If this wet your appetite, also check out the paper Enigma Machine we covered during Hackaday’s first year.

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Inexpensive Robot Platform Combines Mass-produced Parts

Meet Bilibot, a modular robot that aims to lower the cost of entry for robotic tinkerers. It combines the Kinect, the iRobot Create, and an Ubuntu box running ROS using some laser cut mounting brackets. These are relatively inexpensive components but the most exciting thing is that there’s already a slew of example out there that use this hardware. For instance, we looked in on ROS body tracking in January that can be directly plucked and used with this hardware. You’ll recognize the base as the iRobot create which was used in video chat robot from last week. The brains of the operation come in a choice of three Linux boxes – two headless and one laptop – which have ROS pre-installed. Watch the open-source autonomy as it tools around the office in the video after the break.

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