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6 May 2014

NewImage60

Phys.org has the story on the latest in photovoltaics.

Northwestern University researchers are the first to develop a new solar cell with good efficiency that uses tin instead of lead perovskite as the harvester of light. The low-cost, environmentally friendly solar cell can be made easily using “bench” chemistry—no fancy equipment or hazardous materials.

“This is a breakthrough in taking the lead out of a very promising type of solar cell, called a perovskite,” said Mercouri G. Kanatzidis, an inorganic chemist with expertise in dealing with tin. “Tin is a very viable material, and we have shown the material does work as an efficient solar cell.”

Kanatzidis, who led the research, is the Charles E. and Emma H. Morrison Professor of Chemistry in the Weinberg College of Arts and Sciences.

The new solar cell uses a structure called a perovskite but with tin instead of lead as the light-absorbing material. Lead perovskite has achieved 15 percent efficiency, and tin perovskite should be able to match—and possibly surpass—that. Perovskite solar cells are being touted as the “next big thing in photovoltaics” and have reenergized the field.

Kanatzidis developed, synthesized and analyzed the material. He then turned to Northwestern collaborator and nanoscientist Robert P. H. Chang to help him engineer a solar cell that worked well.

“Our tin-based perovskite layer acts as an efficient sunlight absorber that is sandwiched between two electric charge transport layers for conducting electricity to the outside world,” said Chang, a professor of materials science and engineering at the McCormick School of Engineering and Applied Science.

Environmentally friendly solar cell pushes forward the ‘next big thing in photovoltanics - [Link]

6 May 2014

DI5454f1

by Roy McCammon:

The traditional three op-amp differential amplifier’s signal to noise ratio can be improved by 6dB by adding a resistor and slightly changing the connections. There is a trade-off though: The traditional topology has a high input impedance, whereas the low-noise version has a lower input impedance.

Differential amp has 6dB lower noise, twice the bandwidth - [Link]

6 May 2014

BLDC-600x412

Nich Fugalfrom @ Makeatronics is working on a BLDC motor controller.

Icall it a smart BLDC commutator. In a nutshell it’s a dedicated atmega328 that monitors the hall effect sensors on a brushless DC motor and takes care of the commutating and driver circuitry.

It’s smart because it has the ability to extract and keep track of motor position while monitoring the hall sensors. There’s also an option to plug in a quadrature encoder for higher resolution. The position can be sampled via a sample and hold input and communicated to a host controller via SPI.

I designed it to be an easy to use black box for interfacing with BLDC motors. All the host controller has to do is feed it direction (high/low) and PWM and the rest is done for you.

[via]

BLDC motor control using Atmega328 - [Link]

6 May 2014

MC_AN18.15

Design your PCB involving QFN or DQFN packages with this App note from Microchip.

Successful implementation of QFN and DQFN packages requires special consideration for printed circuit board (PCB) layout and solderpaste stencil production. This application note describes the important items to consider.

QFN packages are physically robust, thermally efficient, and occupy much less PCB space than equivalent QFP packages. They generally have superior lead inductance characteristics. They also present some particular design constraints. QFN packages generally have a row (QFN) or two (DQFN) of perimeter pads (“pads”) around a larger central pad (“flag” or “Epad”) encapsulated in a plastic body. These packages are surface-mounted to the target system PCB by a solder reflow process.

[via]

App note: PCB Design Guidelines for QFN and DQFN Packages - [Link]


5 May 2014

3114-1

The LTC®3114-1 is a versatile, wide operating voltage range synchronous monolithic buck-boost DC/DC converter with programmable average output current. The LTC3114-1’s proprietary buck-boost PWM control circuitry delivers low noise operation across the entire operating voltage range. Current mode control ensures exceptional line and load transient responses.

LTC3114-1 – 40V, 1A Synchronous Buck-Boost DC/DC Converter with Programmable Output Current - [Link]

5 May 2014

2338

The LTC2338 fully differential 1Msps SAR ADC family offers a wide ±10.24V true bipolar input range for high voltage industrial applications. The proprietary internal reference buffer maintains less than 1LSB error during sudden bursts of conversions, enabling true one-shot operation after lengthy idle periods. The internal reference can be overdriven to interface to a range of signal levels that swing above and below ground. The LTC2338 family eliminates complicated circuitry required to interface true bipolar signals to ADCs, and provides a compact solution for easy interfacing to 1.8V to 5V serial logic. The LTC2328 offers similar performance with a pseudo-differential input.

LTC2338-18 – 18-Bit, 1Msps, ±10.24V True Bipolar, Fully Differential Input ADC with 100dB SNR - [Link]

5 May 2014

This device is a receiver circuit for a Digital Remote Thermometer. The thermometer operates by converting the sensor’s output voltage, which is calibrated and proportional to the measured temperature, to output cycles. The output cycles are transmitted in the supply cables and the receiver section counts the cycles from the transmitter; the calibrated counting are then displayed in the 7-segment LED displays.

The receiver circuit uses the 4093 Quad two input Schmitt NAND Gate IC as one of the logic components. Another component used is the 74HCT4520 dual 4-bit synchronous binary counter which is a high-speed Si-gate CMOS device. It has a dual 4-bit internally synchronous binary counters with an active high clock input and an active low clock input and buffered outputs. In this circuit, only two output levels from each of the binary counters, are utilized and the rest are connected to ground.  The 74HCT4520 is coupled to the 74HCT4017 5‑stage Johnson decade counter for synchronized clocking. The MC14553B 3-digit BCD counter is also used in this circuit. The MC14553B consists of three negative edge triggered BCD Counters that are cascaded synchronously. In this circuit, the MC14553B controls the most significant (leftmost) value of the thermometer display. Lastly, the HEF4511B  BCD to 7-segment BCD decoder is coupled to the MC14553BCP 7-segment displays. The HEF4511B decoder controls each of the displays to indicate the calibrated temperature.

The circuit is ideal for room temperature measurement. It displays the temperature in centigrade within the range of 00.0 to 99.9 degrees centigrade. Adjustments in the circuit are necessary to change the temperature ranges that can be accommodated by the circuit. Read the rest of this entry »

5 May 2014

What’s inside a $13K Agilent Source Measure Unit capable of 15fA and 100nV resolution?

EEVblog #607 – Agilent B2912A Source Measure Unit SMU Teardown - [Link]

5 May 2014

dds_gen_output_board

by Kalle Hyvönen:

Every once in a while I’d have needed a function generator but since I didn’t have one I always had to resort to some sort of quick and poor 555 kludge or something similar. I spotted a nice looking DDS (Direct Digital Synthesis) kit meant for the Juma RX-1 receiver that uses the AD9833 DDS chip. I figured I should be able to use it as a function generator because the frequency range looked pretty nice (0-8MHz in 10Hz, 100Hz, 1kHz or 100kHz steps) for my needs.

I ordered and built the kit and got it running easily, next thing I had to do was to design and build an output amplifier for the DDS board because the output was just around 250mV peak-to-peak. I wanted around 5V peak-to-peak (p-p) out so for the first revision I just built a simple non-inverting op-amp amplifier with an AD847 op-amp and +-5V supplies and a gain of 25. The +-5V supplies were generated with a 78L05 regulator and a ICL7660 charge pump from a single supply. It did not work too well because the opamp was too slow for a gain of 25, so I got massive attenuation at higher frequencies.

DDS Function Generator - [Link]

4 May 2014

devicecouldb

(Phys.org) —A device created by UCLA researchers could lead to a significant leap in the quality of images on smartphones, computer displays, TVs and inkjet printers.

The new material, and a new manufacturing process developed at UCLA, are used to produce semiconductors that are essential to liquid crystal displays and organic light-emitting diode, or OLED, displays.

Led by Yang Yang, the Carol and Lawrence E. Tannas Jr. Professor of Engineering at the UCLA Henry Samueli School of Engineering and Applied Science, the team created a high-performance device that can be produced without requiring a clean room or the expensive equipment now commonly in use.

Device could boost image quality for phones, computers and TVs - [Link]



 
 
 

 

 

 

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