by Francois AUGER & Philippe Fretaud:
Many previous Design Ideas [1, 2] have shown how to use the Charlieplexing technique  to drive as many LEDs as possible with a minimum number of I/O lines. This Design Idea shows how you can drive three LEDs and scan three switches with only three I/O lines instead of six. Using the same principle, it will also be possible to manage four switches and two LEDs, or five LEDs and one switch. It works well with Atmel ATmega microcontrollers including the Arduino, and could be of particular interest for any eight-pin devices, or when you’ve simply run out of I/O.
3 pins, 3 LEDs, 3 buttons - [Link]
Johannes’ Numitron GeekWatch features Numitron tubes housed in a hideous 3D printed case:
Numitron tubes are cut-down version of Nixie tubes, but instead of having a wire-mesh anode with a cold-cathode display, uses a seven-segmented indicator commonly found on digital meters and clocks.
Old School Tube Watch - [Link]
Alan Parekh of Hacked Gadgets writes:
Thanks to GearBest for sending in this Opus BT-C3100 V2.0 Intelligent Battery Charger for review. at a quick glance this charger might look like any other charger that you see at the grocery store. Your generic store bought brand probably also has 4 charging bays for AA and AAA batteries, it probably has 2 charging circuits which places 2 cells in series to charge them, it most likely has 2 charging lights which just turns off when charging is done. If you leave the batteries in your generic charger you will most likely have batteries that have been overcharging or running down. Also your generic charger can probably just charge one chemistry of battery.
When you have a closer look at the Opus BT-C3100 V2.0 Intelligent Battery Charger you can see how this system differs from your every day generic battery charger. It can auto detect and charge NiCd, NiMH and Li-ion batteries. It charges each cell independently preventing bad cells from interfering from other cells from charging properly. Forget charging lights, this has a full LCD display that provides tons of status. It will monitor batteries that are left in the charger and keep them topped up and ready to go. From here the features go on and on. Don’t let the small package fool you, there is a ton of smarts and features built into this small package.
Have a look at the pictures below and in the video for a look inside the charger. The construction is a dual sided SMD load, the construction looks very professional. The battery contact spring tensioners work well and the connection to the PCB has been beefed up with a thick metal bar…
BT-C3100 intelligent battery charger teardown - [Link]
TechBitar shared his latest project the BridgeDuino with boards from DirtyPCBs:
BridgeDuino is a Swiss army knife PCB for rapid networking of inexpensive wireless communication modules. Breadboards are super for one-off experiments. But after prototyping half a dozen wireless prototypes involving more than just two Arduinos, the wiring mistakes and associated debugging grew more time consuming.
I also wanted a PCB that can act as a shield to Arduino Uno as well as work with the inexpensive and low-power Arduino ProMini.
As of this release, BridgeDuino supports the following wireless technologies/modules:
IR Transmiter LED 940nm
IR Receive 38Khz
RF433Mhz FS1000A Transmitter
Bluetooth HC-06 & HC-05
BridgeDuino: A wireless Arduino HUB and shield - [Link]
Rugged, great sounding boomboxes for all of life’s adventures.
DemerBox is a rugged, great sounding, water-resistant boombox that you can put things inside. The Bang is our single speaker model. Its about the size of a lunchbox but don’t let its svelte size fool you. The Bang gets loud, has tight punchy bass, and pleasing mids and highs. The Big Bang is our two speaker model. Its about the size of a soccer ball. The Big Bang gets louder than The Bang, and because it has two speakers, you get stereo separation and a little more detail in the music.
DEMERBOX – Rugged Wireless Boomboxes - [Link]
Bastl3r wrote this instructable detailing the build of his guitar booster pedal project:
I chose an overdrive pedal design off of generalguitargadets.com (Schematic) and modified it like this:
added a simple positive/middle/negative supply
added a noise filter I found on beavisaudio.com right after the DC Jack (Huminator)
took away the clipping diodes on the output
connected the diodes in the feedback path directly
added the switch to change the resistance of the feedback path (10k <->30k)
Guitar booster pedal (MPX-1) - [Link]
If you have an application, where you work with kilovolts and you need a suitable diode, we have a solution for you.
It´s not a quite common thing, to find a diode with a reverse voltage of more than 1000V in your “home-drawer stock”. But you develop a device, requiring a diode with a substantially higher reverse voltage and nothing suitable is by a hand …
The help is simple – use the DD1000 diode or in case of higher currents, choose a suitable type from the portfolio of High-voltage types from Diotec and send us your requirement. DD1000 features VRRM up to 10 000V, but in respect to its small dimensions and a construction, it´s suitable only for currents up to 20mA. This is sufficient for construction of various testers, voltage multipliers and similar. Should you require higher currents, many suitable types are available, which still maintain compact dimensions. For more powerful designs, it´s possible to use for example a cylinder type SI-A („hockey puck“) with a screw connection allowing for simple series connection (eventually also with RC cell).
Direct 10 000V where ever you need - [Link]
Here’s a proximity-sensing LEDs project by Will_W_76. He writes a complete step-by-step instructions:
So how does this all work? What makes it proximity-sensing? Remember in the explanation above that the photo-transistor acts like a switch. So when the photo-transistor is off, no current is flowing across it to our blue LED and the LED is off as well. Now look at the other side of our circuit. That’s where the IR LED is connected, and it is connected such that it is always on and emitting 880nm infrared waves. Remember that I also mentioned the photo-transistor is set to respond best to wavelengths of 880nm? That’s how the proximity-sensing works! When an object (such as your hand) goes over this little “cluster”, IR light of 880nm is emitted from the IR LED. This light reflects off of your hand and back to the circuit. When the photo-transistor picks it up, it turns on allowing current to flow through from the source to our blue LED lighting it up!
Proximity sensing LEDs - [Link]
App note (PDF) on NXP’s Agile I/O expander, discussing its capabilities and how to use it efficiently.
I2C-bus GPIO devices are widely used and expand a control processor’s pins to 8-, 16- or 24- bits of general-purpose input or output. The characteristic of these I/O needs to be accurately known to efficiently use them in a system. This application note will explore the actual electrical characteristics of Agile I/O GPIO pins.
App note: Low Voltage Agile I/O GPIO Input/Output Characteristics - [Link]
Any microcontroller must have I/O pins for taking inputs and providing outputs. The ATXMega32A4U just like any other micro has 34 programmable I/O pins divided unevenly amongst six IO ports. Most I/O ports are 8 bit wide. XMega I/Os have digital, analog and special purpose functions. Some I/O pins have more than one use. A quick view of the XMega I/O pins reveals the purpose of these pins.
XMega I/O Ports - [Link]