Archive for the ‘diy’ Category

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Convert a SIM to a MicroSIM

Thursday, November 10th, 2011

Apple iPad uses a MicroSIM instead of normal SIM card. And many operators can just give you a normal SIM. So what’s the solution? How To Convert a SIM to a MicroSIM with a Meat Cleaver! article tells that you can do the conversion from normal SIM to MicroSIM with a chopping board, a meat cleaver and a pair of scissors – simple! There is a good series of pictures and description how to do the job.

IMG_0129

If you don’t to do the cutting manually, there are commercially made MicroSIM cutters like Fuj:tech microSIM-leikkuri.

Posted in Mobile, diy | 2 Comments »

Open Hardware Journal

Wednesday, November 2nd, 2011

I just saw Slashdot posting mentioning Open Hardware Journal. Open Hardware Journal is a new open technical journal on designs for physical or electronic objects that are shared as if they were Open Source software. It’s an open journal under a Creative Commons license. You can download the magazine in pdf file format and redistribute it for free.

The first issue opens with words “There’s a lot of excellent Open Hardware that you might not have heard of”. It contains articles on many subjects. ‘Producing Lenses With 3D Printers’ explorers the techniques for producing optical quality lenses with 3D printers. Low-quality lenses are produced, and the causes of failure are discussed.

‘Teaching with Open Hardware Submarines’ tells about the MIT Sea Grant College Program that recognizes a need to encourage students of all ages to develop skills in marine science and ocean engineering. MIT Sea Grant transformed the basic outline of a PVC-pipe-based vehicle into a full-fledged build process, and began offering teacher trainings. The open, publicly available build instructions are central to the success of the program.

‘An Open Hardware Platform for USB Firmware Updates and General USB Development’ tells about project that provides the hardware design and software library to implement firmware upgrades and general USB access, as a serial port or a human interface device (HID). The solution, including the USB port, currently fits on a thumbnail-sized section of a PCB, and has component costs of about $4. It is currently in use in the Lightuino LED-driver circuit board and can also connect to the Arduino ICSP port, SPI, i2c, or GPIOs. It can therefore be used to “USB-enable” other simple hardware designs. This project is hosted on github at https://github.com/gandrewstone/toastedCypressUsb.

The Open Hardware Journal needs more stories for next issues. The magazine is also constructing a global catalog of Open Hardware projects at http://wiki.openhardware.org/Catalog.

Posted in Arduino, Computers, Electronics Design, diy | 1 Comment »

Measure with soundcard

Friday, October 21st, 2011

Unless you add a measurement instrument to your computer, you have only the sound card as an analog I/O port. You can use the sound card to digitize ac analog voltages but only within a limited range. You can, however, add some signal processing and measure a wider variety of signals, even those that produce dc or low-frequency outputs. Here some links to sound card measurement projects:

Sound card based multimeter

HOW TO – Modify a PC sound card to allow D.C. voltage measurements

CheapChop: measuring DC with a sound card

Measuring DC with a Sound Card

Measure resistance and temperature with a sound card

Sound card thermometer/ohmmeter

“2-Pound RLC Meter impedance measurement using a sound card,” Elektor, June 2008, pg 64.

ftsoundcard

Posted in Computers, Electronics Design, diy | 1 Comment »

Replacing flashlight bulbs with LEDs

Sunday, October 2nd, 2011

One day I had an old flashlight that had burned light bulb on it. It was a small cheap model powered with two AA batteries. I could fix it with new light bulb, but going through the trouble of trying to find exactly suitable replacement light bulb felt like more than the value of the flashlight.

If I need to replace the bulb with new one, why not convert the lamp to use LED instead.The lamp runs on two AA batteries in series. They give out around 3V voltage. That’s about the same voltage drop many white LEDs have (typically 2.8-3.5V or so). I had earlier found out that some white LEDs can be directly powered with 3V battery without any current limiting electronics. You just need to find out suitable LED. Some small LED lamps are driving white LED with 3V lithium button cells without a resistor! There are LEDs out there with internal resistors. And there are some LED that just work.

The general advice is that DO NOT use LEDS without a current limiting resistor in series with the LED. The forward voltage rating is TYPICAL and can vary from part to part, so while some LEDs may work fine just connected to a battery of the proper voltage, others will be easily over-driven and be destroyed.

Driving an LED with or without a resistor article on the other hand says that if you are able to run your complete circuit with the same voltage as forward voltage of the LED, perfect. No resistor needed. If you try to run run a 3.2 /3.4 volt warm white of a 3 volt power supply, you will get light but not the maximum amount. But usually enough for small flashlight application anyways. I had even used this idea on my LED light ring for macro photography project, so I was pretty comfortable with this idea.

Now all I need was to find suitable LED from my electronics junk box. I could check the datasheet or do measurements to verify suitability of the LED. It seemed that quite many white LEDs can be run from 3V battery without limiting resistor. But it is best to verify with measurement that things work well. I took a random white LED and put it to Kemo M087 LED testing box. I tested the voltage drop of the LED and different currents from 5 mA to 20 mA (and very quicly with 50 mA). The LED seemed to take somewhat less than 3V at 5 mA and 10 mA. At 20 mA the voltage drop was around 3.2V. At 50 mA the voltage drop was around 3.4V. With this data I could expect that with two new AA batteries in series (gives around 1.6V each) the LED would take around 20 mA current and the current would drop from that when batteries wear out. With this data it seems that this LED would work here.

The next step was just building the LED bulb replacement. Here is a small DIY flashlight bulb LED replacement. It consists of the lamp base (small edison base from old broken bulb), 5mm white LED, solder tin and hot glue. The LED anode goes to the center of the light bulb base.

ledbulb

Here is picture of my LED bulb in the flashlight in use.

ledlamp

Now I have a nice working flashlight that is not very bright, but that has a very long battery life.

If this modification looks interesting, then you might wonder how to convert lamps with different number of batteries to LED lamps. With flashlights that use three batteries or mode, the standard method to use would a white LED + suitable current limiting electronics does job. A resistor will work nut switch mode current source is better. For 20 mA LED and 4.5V operation voltage a 75 ohms or 82 ohms resistor will do. For other operating voltages and LED currents, do your own LED resistor calculations.

If your flashlight uses just one 1.5V battery, you will need a switch mode power supply that boosts the battery voltage to over 3V and limits the current. Joule Thief is a nickname for a minimalist self-oscillating voltage booster that is small, low-cost, and easy-to-build. It can use nearly all of the energy in an electric battery, even far below the voltage where other circuits consider the battery fully discharged (or “dead”). The energy is converter to current and voltage suitable for driving white LED. Make a joule thief if you want to drive white LED from one 1.5V battery.

Posted in LEDs, diy | 1 Comment »

Arduino Goes ARM

Tuesday, September 20th, 2011

The whole world seems to be going in ARM’s direction. ARM has practically taken the mobile phone and tablet markets. The latest version of Windows 8 will also run on ARM processors, Raspberry Pi is a $25 ARM based machine etc..

Slashdot tells that now the open source Arduino platform has a new member — the ARM-based Arduino Due announced at the Maker Faire in New York.

Due-300x300

The Due makes use of Atmel’s SAM3U ARM-based processor, which supports 32-bit Cortex-M3 ARM instructions. The SAM3U processor from ATMEL is running at 96MHz with 256Kb of Flash, 50Kb of Sram, 5 SPI buses, 2 I2C interfaces, 5 UARTS, 16 Analog Inputs at 12Bit resolution and much more. This is much more powerful than the current Uno or Mega.

Unfortunately the 3.3V operating voltage and the different I/O ports are going to create some compatibility problems. Arduino boards have been traditionally with 5V I/O, although 3.3V seems to become more and more popular. Adafruit has a tutorial on converting Arduino Unos over to 3.3v, from 5v. It’s becoming popular. The usefulness of 5V is diminishing.

I don’t see this new Due board as a direct replacement for the 8-bit ATmega based Arduinos, but more as a step up up for those looking for more processing power. A port to ARM for the user friendly Arduino toolkit had been long talked, but this is an official ARM-Arduino board with official support in the arduino toolchain.

To connect this board to Internet you will need to have some additional hardware, because Due does not have any built-in network interface. For Arduino use there has been long time Ethernet Shields (different models) and now also official Arduino Wifi Shield.

Posted in Arduino, Computers, Electronics Design, Mobile, Products, diy | 1 Comment »

Circuit board material uses

Thursday, August 25th, 2011

What else can you do with our ubiquitous PC-board material?

We’re all familiar with printed circuit board material, also called PC board or PCB. The most common type is FR-4, with glass-epoxy substrate (see here), but there are other materials available, such as low-cost, easily punchable phenolic.

FR4 is a strong, stiff, hard-to cut, tool-dulling, and very useful material which engineers use in many product roles besides its primary purpose of provide real estate and interconnect circuits, of course.

It’s a quick and effective way to build a shielded box around a sensitive sub-circuit, since you can quickly solder the edges and get very good RFI/EMI attenuation.

But the real beauty of this PCB material is its many non-circuit uses.

smd_soldering

Posted in diy | No Comments »

Ruggeduino

Tuesday, August 23rd, 2011

There are many Arduino-compatible microcontroller boards nowadays. The Ruggeduino is a ruggedized Arduino-compatible microcontroller board. Features include overcurrent and overvoltage protection on all I/O pins and 5V/3.3V outputs, ESD protection on all I/O pins and USB port, total microcontroller overcurrent protection, and operation at up to 24V.

There are some things a regular Arduino will tolerate; other actions will destroy it immediately. The Ruggeduino designers took all the common mistakes that people make with their Arduinos and designed the Ruggeduino to protect against them. The Ruggeduino web page has lots of technical details how the protection is implemented.

am010_iopinmodel

I have not personal experience in this The Ruggeduino product, but looks interesting. And the technical details how protection is implemented could be useful in some other application some day.

Posted in Arduino, Electronics Design, Products, diy | No Comments »

Bad electrolytics now in my PC

Wednesday, August 17th, 2011

Why modern high tech electronics fail? Too often the reason for that is electrolytic capacitor failure. I have had a quite high number of electronics that has failed by this reason after few years of service. I have had a quite number of devices failed by capacitor: PC motherboard, PC graphics card, set-top-box, DVD player.

Last device that had it’s electrolytic capacitors failing was the graphics card of my Fujitsu-Siemens PC. Was the failure due bad quality capacitors or due bad design I can’t say for sure, but I expect both have had their influence in this. It is not a good idea to place the capacitors to place where the hot air coming from the GPU heat sink cooks them…

graffakortti

Four capacitors capacitors on the picture have “exploded” with noticeable “bang”. It was quite amazing that even after this incident the graphics card almost worked well for some time (showed some errors in picture and sometimes crashed the computer). After replacing the capacitors with new high quality low ESR electrolytic capacitors the graphics card worked again flawlessly. Again components that cost few Euros and some soldering work gave the life back to this computer.

My earlier Electrolytic capacitor failures posting gives more details on this too common failed capacitors problem.

Posted in Computers, Electronics Design, diy | 4 Comments »

Arduino UNO review

Monday, August 8th, 2011

I have participated in Free Product Road Testing program by Farnell. Farnell indentified my blog to road test some of their products. I was willing to participate, because what’s more fun than free high tech products to test. The first product i got was Arduino UNO.

arduino_uno

Arduino Uno is a a microcontroller board based on the ATmega328. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. Something I am already used to see on Arduino boards. And looks what I expect from Arduino board.

The Uno is the latest in a series of USB Arduino boards, and the reference model for the Arduino platform. The Uno differs from all preceding Arduino boards with USB connection in that it does not use the FTDI USB-to-serial driver chip (like Arduino Dueminanove board I already own).

An ATmega8U2 on the board channels serial communication from ATmega328 main CPU UART (digital pins 0 and 1) over USB and appears as a virtual com port to software on the computer. Arduino Uno USB connection is designed operate in exactly the same way as a Duemilanove and maintain perfect backward compatibility with the previous model. The new Arduino Uno: what are the implications? article tells that having ATmega8U2 on the board for USB connection also means the Uno can do new things that are a problem for previous Arduino boards.

Having a dedicated ATmega8U2 to take care of the connection allows the Arduino to provide both traditional USB-serial and HID support on the same port, depending on the firmware running in the 8U2. Interesting side-note: Tiny ATmega8U2 used for the Uno USB connection is pretty much the same as the MCU used on the very first Arduino, but with hardware USB support baked in. The ATmega8U2 chip sits on the board next to he USB connector.

ArduinoUnoFront240

I only played with traditional USB-serial connection on my tests. The ‘8U2 firmware is designed to use the standard USB COM drivers, and no external driver should be needed. So in theory using should be easy. I was waiting for a painless installation. However, on Windows, things too often just don’t work “plug&play”. The problem lies in fact that Arduino Uno is being issued its own USB vendor ID, and Windows (Vista in my case) does not know about it. To make the board to work correctly on Windows the installation of ArduinoUNO.inf file from open-source Arduino environment driver directory is needed. There are some manual installation tricks that needs to be done to get things to work, but fortunately Getting Started w/ Arduino on Windows document gives the needed instructions. I was expecting to get easier installation than with previous board, but this “no driver needed” driver installation process is actually somewhat harder than driver installation for older Arduino boards. Anyway when it is once done things run smoothly.

The Arduino Uno can be powered via the USB connection or with an external power supply. I used USB power on my first tests. The Arduino Uno has a resettable polyfuse that protects your computer’s USB ports from shorts and overcurrent (mistakes can happen when you prototype and play with electronics ideas). That’s a good idea although most computers provide their own internal protection (I think USB specs ask for that). In any case the on-board fuse provides an extra layer of protection.

After some testing with Arduino environment version 2.2 I got things to work. I needed to select right serial port and right board type.

First test was to upload StandardFirmata to the board and control the Arduino UNO board with toolduino.

toolduino_uno

My opinion overall is that the Uno is a very nice board. It maintains backward compatibility while adding the potential for interesting new functionality. This is a great board for prototyping and all kinds of microcontroller hacks.

If you want to buy Arduino UNO you can get it from Farnell. Their list price seems to be 24,35 € without taxes.

Posted in Arduino, Computers, Electronics Design, Products, diy | 4 Comments »

Technique: Carbon Fiber Primer

Tuesday, August 2nd, 2011

It seems as though nearly everything “high performance” these days boasts some amount of carbon fiber in its construction. Originally used in aerospace, carbon fiber has moved into the mainstream.

Technique: Carbon Fiber Primer article from MAKE Magazine discusses some of the basics of carbon fiber construction and explains how to create a carbon fiber iPod case. Could carbon fibers to be useful construction material for the box for your next electronics project? Looks promising.

Posted in diy | 1 Comment »

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