Energy efficiency is a talked about a lot. The Department of Energy is offering a prize of as much as $10 million to create the first solid-state replacement for the 60W incandescent light bulb, so you know it’s a problem. Solving the LED-driver challenge for light-bulb replacement article offers some suggestions for how to address high-efficiency, power-factor, and phase-dimming-compatibility requirements.

When designing LED lamps you need to take into account the heat generated by the LED. Most of the electricity that goes to LED still gets converted to head instead of light, and you need to get rid of it in some way. Light-emitting diodes (LEDs) don’t like heat. Heat shortens their lifetimes. With LED power levels rising, engineers need to find new ways to dissipate heat or use the old ways better. Dealing with LED Heat discusses on the issues hot to get rid of the heat generated by high power LED. Incandescent bulbs eliminate their heat through radiation, whereas with LEDs it’s more of a mechanical issue.

The theremin is an early electronic musical instrument controlled without contact from the player. It is named after its Russian inventor, Professor Léon Theremin, who patented the device in 1928. Theremins are distinguished by the fact that they are played without the performer touching the instrument. The musician moves his or her hands in proximity to the theremin to control the tone of the sound. I was told that mastering the theremin requires skills and lots of practicing, but only a few instrument provide the unique visual appearance of performance. The sound is quite unique for that instrument. Even if you don’t know theremin by name, you might have heard the sound of it at The beach boys -good vibrations or on the sound offects of some old scifi/horror movies.

The electronics of the theremin consists of two high frequency oscillators connected to antennas. When the player moves hand near the antenna, that changes the frequency of the oscillators, and that changes the sound (frequency or amplitude depending on antenna). Here is a block diagram of theremin from www.thereminworld.com Fred Tells All article.

All DIY persons now interested in theremin instruments can also view Make a Theremin video and check ePanorama.net theremin links.

They carefully manipulated the operating voltage of the computer electronics (FPGA). This causes it to make small mistakes in its communications with other clients (if it would make big mistakes it would crash). These faults reveal small pieces of the private key, and enough faults allows the researchers reconstruct the key offline. It takes considerable amount of time (100 hours) and many servers (

For more details read the whole FaultBased Attack of RSA Authentication paper. It describes an end-to-end attack to a RSA authentication scheme on a complete FPGA-based SPARC computer system and demonstrates that a fault-based attack on the RSA algorithm is possible.

It is highly unlikely that a hacker could use this approach on a large institution, so the risk of this to you could be pretty low. The researches say that a common cryptographic technique called “salting” that changes the order of the digits in a random way every time the key is requested, can help to fix this problem. There could also be other solutions as well (maybe better hardware more immune to error).

Image source: http://www.eecs.umich.edu/~valeria/research/publications/DATE10RSA.pdf

Embedded systems are a different story. In many SOC (system-on-chip) applications, signal processing consumes the majority of the execution time. Using normal mathematical libraries for processing data is expensive in terms of both CPU time and memory usage. Acceleration of program execution article gives you information how to speed up the program execution beyond what you get with normal libraries. The article is written from an electrical engineer’s POV (point of view) and focus on the implementation in a given processor and the tradeoffs in implementation methodologies.

One popular technology to speed up the mathematics is to use look-up tables. Lookup tables trade between processing resources and execution time to speed up execution of computational processing. There is always tradeoff between execution time versus design time, and accuracy verses memory usage. Acceleration of program execution contains useful discussion and practical case studies that show that the lookup table method does accelerate program-execution speed considerably. In embedded applications the accelaration of program execution usully means that you can use a cheaper microprocessor and/or use less power than what would be the case with non-optimized program.

How low can 32 bits processors go? article tells you this and the fact, but also that this is not the whole story. 8-bit controller have their advantages still in applications where their processing power is enough. It is true that 32-bit cores are pushing everywhere (more capabilities and easier to program), but there are still applications where there is good place for 8-bit processors.

Many consumer HIFI equipment and other audio signal sources offer only unbalanced outputs. Unbalanced interconnections pick up easily all kinds of noise (especially ground loop noise), so you might want to avoid them everywhere you can.

You can convert the simple unbalanced preamp output to balanced circuit with one of the  following tricks:
- Use a DI box to convert unbalanced signal to balanced microphone level signal
- An audio transformer is a classic way to convert unbalanced to balanced
- Balanced opamp output circuit can convert unbalanced to balanced (more modern approach but more components)

In addition to those there is not so widely mentioned impedance-balanced output option:

1. Figure out the output impedance of your unbalanced signal source. Usually looking at the circuit diagram of the device will tell you that easily. If you don’t have that, you can always measure the output impedance.
2. Pick a resistor that has same resistance as the output impedance of your unbalanced output (as close as possible… preferably within 1% accuracy).
3. Wire the unbalanced output signal to XLR pin 2 (+).
4. Wire ground to XLR pin 1 (ground).
5. Wire that resistor you just selected between XLR pins3 (-) and pin 1 (ground).

Now you have a impedance-balanced output. It is not exactly as good as a real balanced output, but performs pretty close a real balanced output in normal applications. You can use the same idea also with 6.3 mm jacks: signal goes to tip and the resistor to ring. An impedance balanced output with 6.3 mm jacks works as well as an unbalanced output if that is what is needed (just plug in a cable with mono plug).

Impedance-balanced principle has been used some professional electret mics and on outputs of some “budget” mixers! Just by adding one resistor an unbalanced output is converted to impedance balanced output that works very well with all equipment that has balanced inputs.

More information on line balancing and theory can be found at great The Self Site Balanced Line Technology document.

To display manufacturers, this new panel technology is expected to be the next big thing (in addition to 3D). Display manufacturers have been talking about OLED televisions and monitors as “a couple years away” for at least the last half-decade.

Unfortunately, it seems that everything hasn’t worked out too well for OLED. Sony Kills Next-Gen 11″ Display; Manufacturers Hedge on OLED TVs article tells that Sony announced it would halt sales of its 11″ XEL-1 OLED in Japan, where the panel first debuted. Sony’s decision to kill the unit in its home market and reduce the rate at which it’s investing in future OLED TV development has been perceived in some corners as a judgment on the long-term feasibility of OLED technology. In the wake of Sony’s announcement, far too many online pundits have rushed to declare OLED panels dead, dying, moribund, or otherwise abandoned.

I think this case does not yer prove that. Sony OLED case was just proven that people currently don’t want to spend kilobucks on technology that’s not even ready from prime time because LCD LED and Plasma TVs are “good enough” for everyone. Sony XEL-1 is a sub-HD resolution small 11 inch (28 cm) television that cost thousands of dollars and looked pretty ugly, no wonder that it failed. If you are into electronics and want to see what electronics is inside that display, take a look at inside XEL-1 OLED TV display picture.

After this incident we’ll probably see development focus shift at least in short term from large panel sizes to smaller ones, particularly since the smartphone/handheld OLED market. OLED technology will evolve there and maybe some day it will be more ready for the prime time in larger displays. After smartphones the next step would be netbooks/notebook, then laptops and then computer monitors.

Product lifetime and product reliability are different things. Lifetime refers to the length of time an end user can expect a product to work. Reliability refers to how many products per thousand a user can expect to fail in normal use during their expected lifetime. LED component manufacturers often quote lifetimes of 50,000 hours or more for the LED itself, LED because the lighting unit comprises of also many other parts (LED driver/power supply), the actual lifetime of the unit can easily be considerably shorter than the lifetime of the LED itself.

Burn out: Weak links affect HB-LED lifetime article tells that proper selection of capacitors and other components, along with thermal management, can help you save your LED lighting product from an early demise.

Image source:

http://www.logitechsqueezebox.com/product_matrix.html