Electronics-Lab.com Blog

Clayton Grantham writes:

Some years ago, one of the fundamental electronic instruments was the laboratory curve tracer. A CRT display would sweep out terminal behavior (current versus voltage) from which you could derive mathematical models. Classic presentations of diodes, transistors, and other devices enlightened designers about linear and nonlinear operation. From the displays, you could determine the bias points for optimum design performance. Today, however, you rarely find the classic curve tracers in the lab. Instead, you find design-simulation software, such as Spice, that’s removed from hands-on, empirical analysis. Spice models now exist for almost all electronic components. Characterization analyzers still make the voltage-current measurements but not at the design-engineer level. Rather, departments are dedicated to characterizing processes and components and incorporating these characteristics into the simulated models. The low-cost circuit in Figure 1 allows you to return to the hands-on approach by using your PC as a limited curve tracer.

Trace voltage-current curves on your PC - [Link]

DUE ARM-powered Arduino – [via]

Far removed from the legions of 3D printers featured at this year’s Maker Faire in New York was a much smaller, but far more impressive announcement: The ARM-powered Arduino DUE is going to be released later this month.

Instead of the 8-bit AVR microcontrollers usually found in Arduinos, the DUE is powered by an ATSAM3X8E microcontroller, itself based on the ARM Cortex-M3 platform. There are a few very neat features in the DUE, namely a USB On The Go port to allow makers and tinkerers to connect keyboards, mice, smartphones (hey, someone should port IOIO firmware to this thing), and maybe even standard desktop inkjet or laser printers.

ARM-powered Arduino - [Link]

Raju Baddi writes:

A specialized test gadget that tests continuity quantitatively in both AC and DC modes could prove to be an indispensible bench test instrument. This article describes such a continuity test set up, which provides two different display options.

The meter (see Figure 1) can be used in AC mode to test/estimate capacitors, inductors, transformers etc. that are sensitive to AC current, while the LEDs can be used in AC/DC mode to test diodes, transistors, transformers, etc.

Method tests continuity in AC and DC - [Link]

drcurzon writes:

This version is much more secure and could easily be used across the internet with very few security concerns. A brief outline:

• A server program that runs on the Raspberry Pi to read variables
• A MySQL database to store the variables in
• An Apache2 served webpage to allow control of the variables

Web Control of Raspberry Pi GPIO - [Link]

tuomasnylund.fi writes:

There’s something fascinating about electromagnetic fields. Thanks to the modern world and the prevalence of electronics and electricity, they’re all around us these days. But because of the extremely limited array of senses that we humans have, we spend most of the time completely oblivious of them. Wouldn’t it be cool to make something simple that could not just detect them, but would allow you look at the waveforms on an oscilloscope. An EMF probe in other words.

A Simple EMF Probe - [Link]

LT series LED drivers with 10-100W power represent a complete solution with wide possibilities of control. Exceptionally narrow and slim design, remained even at high-power versions, provides a high flexibility of use.

Power supplies for LED lighting (so called drivers) are available from many producers, in a various qualitative level. Why to decide just for the LT series from German company Friwo? Here are few reasons:

• precise design, safe operation and a long lifetime
• voltage and current regulation in one device
• high efficiency and a possibility of dimming in a range of 0-100% directly via a CTRL pin
• modules are available in 10-100W power, with a possibility of customization by laser directly at production also available a module for dimming – so called DIMMbox, further expanding possibilities of control (switch, 1-10V, DALI) and with a possibility of synchronization with up to 1000 slave units
• very small cross section of modules (21x30mm, resp. 24x30mm at LT100) – applicable even in very tiny conditions

Wide control possibilities of LT series modules are perhaps the most interesting. Modules contain a galvanically isolated CTRL input, by which it is possible to switch on/ off the module without disconnecting from 230V mains. CTRL pin also serves for regulation of an output current. For this purpose, only one resistor (or a potentiometer) is necessary – connected between SEC+ and CTRL pins, with a value counted by a simple formula in the datasheet. The output current can also be controlled by an external voltage in the range of 0-1,8V connected to SEC- and CTRL, as well as by means of a PWM TTL (0/5V).

Further possibilities of control are provided by a standalone additional module DIMMbox. DIMMbox operates as an (almost) lossless PWM regulator with a MOSFET switched at f=600Hz. DIMM-BOX connected to any series LT driver enables to regulate an output current in a range of 10-100% or 0% (OFF) via a usual switch (switch-dimm“ mode), via a linear voltage 1-10V and also a DALI interface. DIMMbox tests after switching on, which of three methods of control is used and consequently accepts only signals from a given input – until switching off the module. DIMMboxes can be connected through SYNC inputs, ensuring the same level of dimming for all modules. Enclosed pictures will provide you the best idea about possibilities of connection.

Friwo drivers not only drive your LEDs but even control them - [Link]

lightnin9 writes:

Now everybody knows it’s way smarter to just pay someone to host your website. But what not everybody knows is that it’s way more punk rock to Do it Yourself. So what follows are some tips / pointers / instructions for setting up your own home webserver (which will burn a scant 2 watts) using all free, open source software, a Raspberry Pi, and your home internet connection.

The emphasis here is on lightweight, which fits well with the Raspberry Pi. Sure, you can setup a blog with wordpress or Django, and they will run (I’ve tried it, at least with Django). But they probably will run rather slowly. Why? The rPi doesn’t have a lot of memory or processing power, and a database / front end model requires a decent amount of that. If your site / blog ever gets much traffic, it’ll likely buckle under the load. The answer? Just serve up plain old static HTML pages. It’s fast, secure, simple, and easy on the rPi’s limited resources. But rather than painstakingly handcodeing each new blog entry, you can use a static html generator like Pelican to make it easy

Host your own blog from a $25 Raspberry Pi computer - [Link]

tuomasnylund.fi writes:

One tool that I’ve been missing at my lab at home is function generator. They tend to be a bit expensive, so I haven’t bought one. I thought this might be a good opportunity to try and make one myself. I found a pretty common DDS (direct digital synthesis) chip, called AD9833. Then just strap a USB-enabled AVR micro there and maybe some analog electronics.

This board doesn’t do any of the special analog magic to allow for variable amplitude or offset for the signal. The output is fixed to 0-4v. I’m planning to make another completely analog board for adjusting amplitude and offset.

AD9833 – based USB Function Generator - [Link]

Steven Keeping writes:

Lithium-ion (Li-ion) batteries have become popular for portable electronics such as laptop computers and smart phones because they boast the highest energy density (capacity per unit volume) of any commercial battery technology. Other benefits include thousands of recharges and no occurrence of the “memory effect” that plagued early nickel cadmium (NiCd) rechargeable cells.

However, it has been a tough design challenge to get the technology to where it is today. Lithium is a highly reactive material that can, for example, burst into flames if it comes into contact with water. Engineers and scientists have worked hard to develop novel compounds that can leverage the advantages of lithium while producing inexpensive, reliable, and safe batteries.

A Designer’s Guide to Lithium Battery Charging - [Link]

Introduction to Octopart – [via]

Here at Octopart, we put lots of effort into building new features to help you find electronic parts fast. Now we’re going to show you how to use those features. Below is our first Octopart tutorial video: an introduction of the site’s basic features. Let us know what you think in the comments!

Introduction to Octopart (video) - [Link]