Foldable array of solar cells printed on a sheet of paper

 

The sheet of paper looks like any other document that might have just come spitting out of an office printer, with an array of colored rectangles printed over much of its surface. But then a researcher picks it up, clips a couple of wires to one end, and shines a light on the paper. Instantly an LCD clock display at the other end of the wires starts to display the time.

Almost as cheaply and easily as printing a photo on your inkjet, an inexpensive, simple solar cell has been created on that flimsy sheet, formed from special “inks

Quick and Easy Wireless system

pyroelectro.com writes:

One frustrating moment in do-it-yourself electronics is when you hit the limit of using ‘wired’ electronics and need to go to wireless. Wireless electronics are frustrating because typically unless you are very knowledgeable you cannot easily build them yourself. This means you either need to study until your eyes bleed or you have to use pre-made modules.
This tutorial will explore how to add and use common remote control car transmitter and receiver pairs in your microcontroller projects. Specifically the received protocol will be translated into information the pic can use to create some output from the remote control’s input.

Quick and Easy Wireless system – [Link]

How to send data from Arduino to Google Docs Spreadsheet

open-electronics.org writes:

A very interesting feature of Arduino is the great avalaibility of library that make the developer work very simple and fast.Make a Web Server, a Web Client or post a Tweet haven’t difficulty. Try to do the same application with the Microchip’s Stack TCP/IP…. It’s not impossible but for beginner developpers is of course hard. With the Ethernet shield or WiFi shield you can connect your application to the internet world, get information, send email, post data…

Post data? But where? Some site host your data with graphics like the famous Pachube, I also use this service for my projects. But in some case could be useful have the data in a spreadsheet to do operations and evaluate numbers. In this post I want explain the best way to send data on Google Spreadsheet.

How to send data from Arduino to Google Docs Spreadsheet – [Link]

Sound Card Microcontroller / PC Communication

swharden.com writes:

I developed a nifty way to send data from any microcontroller to any PC running any operating system with zero components and hardware you probably already have sitting in front of you.  Traditional interface methods (namely serial port and usb port, both have been referenced on Electronics-Lab) have drawbacks. For serial, you need a level converter IC (like a max232) and an archaic PC with a serial port, or a USB serial port adapter (many of which don’t run on Linux or newer versions of windows), and a crystal specifically chosen for transfer at a certain bit rate. FTDI makes a series of USB/serial interfaces, but they’re expensive and SMT only I don’t feel like paying even more for a breakout board just to communicate with a $1 microcontroller. Also, many ATMEL chips (most of the ATTiny series) don’t have rs232 capability built in, so you have to bit bang it in software (not fun). USB is another option, but requires a crystal and some level conversion circuitry, and isn’t supported by most small/cheap ATMEL chips. It’s built in some simple PICs (like some of the 18F series) but I don’t want to switch architecture just to send a few bytes to a PC! The V-USB project helps ATMEL chips bit-bang the USB protocol, and I’ve gotten it to work, but it’s not easy (their hello world program is hundreds of lines of code), and you have to mess with writing USB drivers or interfacing pre-made USB drivers with OS-specific solutions, it’s not fun either.

I’ve long wished there were an easier way! In this post, I demonstrate a simple way to send data from a microcontroller to a PC (and a more advanced second example showing bidirectional communication) using PC a sound card! Although the one built in most PCs would work, I decided to do it with $1.30 sound cards that are all over eBay. The chip sends pulses of data to the PC and a Python script (which can be run on virtually any OS) listens to the sound card with the pyAudio library and waits for data. When it’s received, it measures distances between pulses and dumps data values to the screen (optionally logging them to a CSV file ready for graphing by Excel or some other program).  A series of calibration pulses precede the data stream allowing the PC to adapt to incoming data at any speed (no specific clock speed or crystal is required).

Although it’s not a refined method suitable for consumer applications, it sure is a useful hack for anyone looking to quickly exchange data between a microcontroller and a PC!

Sound Card Microcontroller / PC Communication – [Link]

TiDiGino Contest

Open-electronics.org puts a PERSONAL SCOPE HPS50 by Velleman as a prize to the first person that writes a sketch for TiDiGino: the New GSM remote control Arduino based. TiDiGino mount a ATMEGA2560 chip and can be programmed by the Arduino IDE. The TiDiGino library manages the GSM of TDGINO to write easy a sketch.

TiDiGino Contest – [Link]

OpenPiCUS integration with ThingSpeak and hibernation mode

openPICUS is an open source wireless platform that uses Wi-Fi and freeRTOS to connect things to the web. The guys from openpicus released some new applications: One new feature is hibernation mode for lower energy use with battery-powered applications. The other new feature is integration with ThingSpeak. All you have to do is download the ThingSpeak.com Library from openPICUS and use it with your FlyPort Wi-fi device. Now, you can sensors connected to ThingSpeak for data logging, visualizations, and access to all of the ThingSpeak apps, such as ThingTweet and ThingHTTP.

Here’s the video

Voltage monitor for car's battery and its charging system

Car battery and charging system monitor

This project is about making a simple electronic voltage monitor system for car’s battery and its charging system. It plugs into the car’s cigarette lighter receptacle and displays the instantaneous output voltage across the battery terminals on a 4-digit seven segment LED display. This helps you to get early warnings for possible battery and its charging system problems.

Voltage monitor for car’s battery and its charging system – [Link]

Voltage monitor for car’s battery and its charging system

Car battery and charging system monitor

This project is about making a simple electronic voltage monitor system for car’s battery and its charging system. It plugs into the car’s cigarette lighter receptacle and displays the instantaneous output voltage across the battery terminals on a 4-digit seven segment LED display. This helps you to get early warnings for possible battery and its charging system problems.

Voltage monitor for car’s battery and its charging system – [Link]

JFET Phono (RIAA) Preamplifier Kit

There is no doubt that Long-playing (LP) record albums are not for everyone. Some just don’t like the clicks and pops (more so with old vinyl records than new ones). Others don’t like the fact that you have to get out of your seat to turn them over or that you need a turntable and cartridge. Luckily turntables and cartridges, even very good ones, are not expensive these days. Then there is the requirement of an RIAA phono preamplifier.

With the phonograph cartridges only delivering a few millivolts an additional high-gain preamplifier stage will be required. Also when LP record masters are produced the bass is removed from the music to make cutting the master easier and the grooves smaller. The phono preamp has two jobs then: to amplify the small voltages coming from the cartridge and to re-balance the bass against the other frequencies (RIAA equalization). Both tasks are not hard and a few dollars of simple electronic parts is all the required to build a good sounding phono preamp. Or you can take the consumer approach and purchase an inexpensive preamp or pay $10k for a top of the line model.

JFET Phono (RIAA) Preamplifier Kit – [Link]

Single-Ended (SE) 6550 Tube Amplifier Schematic

This single-Ended (SE) 6550 design is based on a minimonitor constructed by Lars Ohlsson of ElektroAkustik & Music.

The single-ended amplifier circuit uses a 6550 high power tetrode vacuum tube in the output stage. A 12DW7 or 7247 is used to drive the output stage. The 12DW7 / 7247 is a dual section triode, the first section has a gain factor of 20 and the second section a gain of 100. You can think of it as one-half of a 12AX7 and one-half of a 12AU7 in the same envelope. New production JJ ECC832 tubes are a suitable replacement for the 12DW7 and 7247 which are no longer in production. C2 and C3 should be good quality film capacitors. The cathode bypass capacitors C1 and C4 will also have some impact on the sound and good quality low ESR capacitors are suggested.

Single-Ended (SE) 6550 Tube Amplifier Schematic – [Link]