High color fidelity approaching an ideal is a common feature of „high CRI“ Osram LEDs with CRI up to 96.
When you recall to lessons of physics from your basic- or grammar-school, probably you´ve heard a term „black body radiation”. As we know, each object with a given temperature radiates in a wide range of wave lengths, while a maximum of a radiation depends on its temperature. We mention it because the Sun also operates on this “principle” and its spectrum (light) depends mainly on its surface temperature. Temperature of an object is also the most important factor influencing whether the light will be “warm” or “cold”, that´s why a term color (chromacity) temperature CCT is used.
Even though a portion of radiation (some wave lengths) is absorbed in atmosphere, it can be said that it is very near to a black body spectrum and it´s ideal for us in respect to a pleasant and true color perception.
There are several methods to evaluate color fidelity and one of the most important is so called CRI (color rendition index, maximum = 100). To an ideal light source with CRI =100 is very near a classic incandescent bulb, even though it´s spectrum is shifted towards warmer tones. Unfortunately a light spectrum gained from hot surfzce object also contains a large portion of thermal (infrared) radiation, what causes a low efficiency of incandescent bulbs. However LEDs deploy emission of photons on an other principle (change of electrons energy), so their surface is in fact “cold” in comparison to what temperature a black body radiator should have to gain a similar spectrum.
Modern LEDs have a high CRI, usually over 70. But among LEDs we can find types with even higher CRI (above 80) , as well as “color champions” with even higher CRI. To such champions also belong LEDs from the OSLON Square series, which we introduced to you in our article New LED OSRAM OSLON Square withstands up to 1.5A. Since then company Osram advanced in development and was able to make types with a typical CRI 96 (!), for example LCWCQAR.CC-MPMR-5J7K-1 (4500K).
Light fidelity of this LED is extremely high and such light is very suitable for lighting of areas with high requirements for a light quality, like for example: galleries, museums, shops, photographic ateliers as well as for an everyday work. Despite a high CRI, this particular type also features a considerable efficiency of 180-224 lm/700 mA and a max. current up to 1500 mA.
Among novelties from company Osram can also be found the Oslon Square 2nd generation with even betterthermal features increasing lifetime and efficiency at high temperatures. Moreover this new 2-nd version is sorted (binning) at 85°C, what ensures minimum color in a real operation.
Almost perfect light from the Oslon Square LED - [Link]
Lee Zhi Xian writes:
I was always fascinated with LED Matrix Display because it makes a good and clear display. I always saw LED display used as advertisement signboard. It can be programmed with variety of animations. So I decided to make myself a 48×8 LED Matrix Display. Of course, I start off with a smaller one by soldering LEDs on stripboard, making a 8×8 LED Matrix. I tried to understand how the LED Matrix works and how to deal with the programming part.
Development of 48×8 Led Matrix Display - [Link]
The PCA9508 is a CMOS integrated circuit that supports hot-swap with zero offset and provides level shifting between low voltage (down to 0.9 V) and higher voltage (2.7 V to 5.5 V) for I2C-bus or SMBus applications. While retaining all the operating modes and features of the I2C-bus system during the level shifts, it also permits extension of the I2C-bus by providing bidirectional buffering for both the data (SDA) and the clock (SCL) lines, thus enabling two buses of 400 pF. Using the PCA9508 enables the system designer to isolate two halves of a bus for both voltage and capacitance, and perform hot-swap and voltage level translation. Furthermore, the dual supply pins can be powered up in any sequence; when any of the supply pins are unpowered, the 5 V tolerant I/O are high-impedance.
PCA9508 has B-side and A-side bus drivers. The 2.7 V to 5.5 V bus B-side drivers behave much like the drivers on the PCA9515A device, while the adjustable voltage bus A side drivers drive more current and incur no static offset voltage. This results in a LOW on the B-side translating into a nearly 0 V LOW on the A side.
The hot swap feature allows an I/O card to be inserted into a live backplane without corrupting the data and clock buses. Control circuitry prevents the backplane from being connected to the card until a stop command or bus idle occurs on the backplane without bus contention on the card. Zero offset output voltage allows multiple PCA9508s to be put in series and still maintains an excellent noise margin.
- PCA9508D CMOS integrated circuit (3 units)
- BUS Master
- Slave 400kHz (3 units)
- 10kΩ Resistor (6 units)
- Ground Source
Hot swap level translating I2C repeater - [Link]
The LT8301 is a monolithic flyback regulator that significantly simplifies the design of isolated DC/DC converters. By sampling the isolated output voltage directly from the primary-side flyback waveform, the part requires no opto-isolator or third winding for regulation. The LT8301 operates over a 2.7V to 42V input voltage range, has a 1.2A/65V power switch and delivers up to 6 watts of output power, making it well suited for a wide variety of industrial, medical, datacom, military and automotive applications. The LT8301 is available in a small TSOT-23 package. Extended and industrial versions operate over a junction temperature range of -40°C to 125°C. A high temperature automotive grade operates from -40°C to 150°C and a military grade operates from -55°C to 150°C.
LT8301 – 42VIN Micropower No-Opto Isolated Flyback Converter with 65V/1.2A Switch - [Link]
Raj Bhatt from Embedded-Lab has posted a detail review of mikroElektronika’s EasyPIC v7 development board (http://www.newark.com/mikroelektronika/mikroe-798/development-system-easypic-v7/dp/63W4082) on his website. EasyPIC v7 supports over 350 PIC microcontrollers including PIC10F, 12F, 16F, and 18F, and contains an onboard fast USB programmer and real-time debugger. The board also features two mikroBUS sockets for tons of other add-on boards, thus expanding its capabilities.
[via the contact form]
Review of EasyPIC v7 - [Link]
ajoyraman @ instructables.com writes:
PC sound cards form a readily available Signal Generator for testing electronic circuits. The utility of these signal generators is limited because the outputs are AC coupled and limited to ±2V.
Taking advantage of the two channels provided by the sound card this Instructable shows a scheme which uses one channel to output the Sin/Square/Triangle waveform with a fixed gain, while setting up a 441 Hz PWM square wave on the second channel. This PWM waveform is converted to ±8V averaged and summed with the first channel to provide a DC offset controllable by the duty-cycle setting.
PC Sound Card Signal Generator Interface - [Link]
bgyroscope @ www.instructables.com writes:
This instructable will show you how to build your own stopwatch to record multiple splits using an ATmega328 programmable microcontroller. When one presses the start button (or slaps the metal band in my watch), the screen displays the last lap for a second then continues the time on the next lap. It’s great for all you runners out there doing an interval workout.
Lap Stopwatch with ATmega328 Microcontroller - [Link]
Evilthingamabober @ instructables.com writes:
Microcontrollers are, without a doubt, amazing little things. They are versatile, powerful, and extremely tiny. Unfortunately, the latter trait is also shared by both my wallet and my programming skills. My understanding of C is poor, and I can hardly afford to buy something like an Arduino or a decent ISP. And in any case, the Arduino would be overkill for many of my projects, which only need simple IC’s.
But as many of you know, DIY always finds a way. This tutorial is meant for those among us with no budgets or programming experience who want to start using these little machines. It is not based around the ATmega328 (the Arduino Uno chip), but rather the Attiny line of chips (the Atiny85 and Attiny2313, to be specific). The total cost of this project can go as lower than $15 if you know where to buy from, and you can still use the original Arduino IDE and language to program your projects in the end. Keep in mind that you will need some soldering skills to get this project done.
The Idiot’s Guide to Programming AVR’s on the Cheap - [Link]
ARPix has posted this instructable on constructing an external serial monitor device using the Atmega328 MCU and a graphic LCD. It allows a user interface to set the serial baud rate and start/stop functions using tact switches.
Sometimes I needed an external serial monitor like the Serial Monitor in the Arduino Editor, to see what is going on. So I made one. For the ESM I used an Atmel Atmega328 because it have an internal SRAM with 2KBytes. It’s necessary for the big data processing. So you need more than 1KByte SRAM.
Constructing an external serial monitor - [Link]
This is a 1-wire absolute pressure sensor based around the Motorola MPX4115A:
The 1-wire weather group is always looking for new sensors and ideas that will allow them to monitor more and more elements, the 1-wire barometer is just one of these sensors. Based around the Motorola MPX4115A absolute pressure sensor, the group has been trying to design / decide on a good interface circuit for quite a long time.
The most commonly used and my personal preference is the Bray series. Both the version 1,2 and 3 designs use the same amplifier with adjustable offset and gain presets, the main difference between the three versions is that the second two versions have dual voltages, 5v and 10v with the amplifier being powered from the 10v rail, this way the amplifier has a greater output range which uses the full input range of the DS2438 ADC, subsequently giving better resolution capabilities.
1-Wire Barometer Project - [Link]