Guidelines for reading an optocoupler datasheet

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by Markus Appel @ edn.com:

Optocouplers, also known as opto-isolators, are components that transfer electrical signals between two isolated circuits by using infrared light. As an isolator, an optocoupler can prevent high voltages from affecting the side of the circuit receiving the signal. Transferring signals over a light barrier by using an infrared light-emitting diode and a light-sensitive product, such as a phototransistor, is the main structure of an optocoupler. On the first page, datasheets provide the main product description, its features, suggested areas of applications, ordering information, and agency approvals, as shown in Figure 1 for the VO617A optocoupler with phototransistor output. Following pages provide key technical specifications, operating conditions, and graphs showing the behavior of the product.

Guidelines for reading an optocoupler datasheet – [Link]

Waffle implant supplies drugs

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by Rob Matheson @ MIT News Office:

An implantable, microchip-based device may soon replace the injections and pills now needed to treat chronic diseases: Earlier this month, MIT spinout Microchips Biotech partnered with a pharmaceutical giant to commercialize its wirelessly controlled, implantable, microchip-based devices that store and release drugs inside the body over many years.

Invented by Microchips Biotech co-founders Michael Cima, the David H. Koch Professor of Engineering, and Robert Langer, the David H. Koch Institute Professor, the microchips consist of hundreds of pinhead-sized reservoirs, each capped with a metal membrane, that store tiny doses of therapeutics or chemicals. An electric current delivered by the device removes the membrane, releasing a single dose. The device can be programmed wirelessly to release individual doses for up to 16 years to treat, for example, diabetes, cancer, multiple sclerosis, and osteoporosis.

Waffle implant supplies drugs – [Link]

MOVI, a standalone speech recognizer shield for Arduino

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MOVI is an offline speech recognizer and voice synthesizer that adds voice control functionality to any Arduino project

MOVI stands for My Own Voice Interface! It is the first standalone speech recognizer and voice synthesizer for Arduino with full English sentence capability:
Up to 200 customizable English sentences.
Speaker independent
Standalone, cloudless and private
Very easy to program

MOVI provides an alternative to buttons, remote controls, or cell phones by letting you use full-sentence voice commands for tasks such as turning devices on and off, entering alarm codes, and carrying on programmed conversations with projects.

MOVI is plug and play! Connect the shield to your Arduino Uno or compatible board, connect an optional speaker, and you’re ready to go.

MOVI, a standalone speech recognizer shield for Arduino – [Link]

The Best NiMh Charger

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Paul Allen build a great NiMh charger that connects to PC for controlling full aspects of charging process. He writes:

It’s been a long time since I posted an update on my battery charger project (in fact it has been a long time since I have posted anything!). I have been Very Busy with projects for my work and when I am not working for work, I am working on battery chargers. When I am not working on battery chargers I am trying to be a good husband and father as well as find time to do things like mow the lawn or fix the handle my son broke off the faucet.

“The Best NiMh Charger” Some may say that is quite the claim, but wait until you see all it can do (mostly thanks to the software Mark my programming friend wrote for it).

The Best NiMh Charger – [Link]

Designing a PIC24 development board

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Brian Dorey has designed and built a PIC24 development board, that is available at GitHub:

One problem we found was trying to prototype code using this microcontroller as unlike Arduino and any ARM microcontrollers there isn’t a small easy to use prototyping board available for the PIC24 chip. Microchip make an Explorer 16 Development Board which is designed to work with the PIC24 microcontrollers but it is large and fairly expensive and is designed to work best with other Microchip addon cards.

With this problem in mind we decided to design and build a small prototyping board that would work with the PIC24FJ128GC006 as well as one of Microchips DSPIC33EP256MU806 dsPIC series microcontrollers. The prototyping board was designed with removable daughter boards for the microcontroller.

Designing a PIC24 development board – [Link]

Optimized Solar Tracking System

The solar energy collection is not that easy compared to the different types of power generation system because it has the lowest capacity factor. It has 5 out of 24 hours in a day that it can generate electricity from its solar collection. The only solution to this is by optimizing the 5 hours solar energy collection. This design features a solar tracker with Light-Dependent Resistor (LDR). The system is managed by a S08 MCU of Freescale. It has flash and RAM access protection that can be used in embedded development security. The system has its own protection such as illegal opcode detection with reset and illegal address detection with reset. It has also power-saving modes in which a peripheral clock-enable-register can disable the clocks of unused modules.

The design is comprised of a MC9S08PA16AVLC 8-bit MCU, S08 core, 16KB Flash that serves as the main controller of the system. It directs the movement of the servo motor with respect to the data gathered by the LDRs. It has four LDRs that will be able to locate accurately the solar radiation at its optimum point while behind these LDRs is the movable solar panel. The solar panel movement is handled by the servo motor that is also controlled by the MCU. The vertical servo is used to adjust the inclination of the panel while horizontal servo is used to adjust the horizontal position of the panel. The smart battery serves as the energy storage of the solar module that can trip off the supplies produced by the solar panel preventing it from overcharging.

The design is applicable to different types of solar module that will be able to optimize their solar energy application. It can be used in a basic robotic arm development since it features the minor movement capability of a robot or use it as a reference in the development of more sophisticated system.

Optimized Solar Tracking System – [Link]

Arduino DCF77 Master Wall Clock

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by oliverb @ instructables.com:

Time displayed on large 1″ (26mm) 7 segment displays with secondary 4×20 LCD information display. The clock can be used stand alone or provides the following pulses to drive slave clocks 1 sec alternating, 30 sec, 1 min , 1 hour, 24 hr, 15 min chime of quarter hours, hourly chime of hours.

An Arduino 328 Microprocessor is used to decode and display time & date from the DCF77 “Atomic” Clock in Mainflingen near Frankfurt Germany.
The DCF77 signal is decoded using the fantastic new DCF77 library written by Udo Klein meaning the clock stays in sync and keeps perfect time even with a massive amount of noise on the received DCF77 signal. Udo Klein’s DCF77 library also continually “Auto Tunes” the quartz crystal so in the rare event the signal can’t be decoded the clock remains accurate within 1 sec over many days.

Arduino DCF77 Master Wall Clock – [Link]

Read multiple switches using ADC

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by Les Hughson @ edn.com:

The ATMega168 is a great general purpose 8-bit AVR microcontroller from Atmel. It has 23 GPIO pins, but sometimes (as I have found) you can run out of I/O pins as your design grows. This happened to me recently when, of the 23 GPIO pins available, 2 were taken up by an external ceramic resonator, 1 for the reset line, 3 for serial coms, 14 for the LCD, and 3 for RGB LED control. This used all 23 GPIO pins, with none left for the four buttons I needed. What to do? This Design Idea has the solution.

A close look at the ATMega168 data sheet revealed that the I/O pins available on the 28-pin DIP package and on the 32-pin TQFP package are not all the same. On the TQFP package, there are an additional pair of VCC & GND pins and an additional two ADC input pins on top of the advertised 23 GPIOs. So if I could read my 4 buttons with these extra ADC inputs, all would be OK and the design would be saved.

Read multiple switches using ADC – [Link]

Samsung Researchers Nearly Double Lithium-ion Battery Capacity

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by GardenState @ element14.com:

Silicon is receiving considerable attention as an active material for next- generation lithium-ion battery anodes because of its gravimetric capacity–a measure in mAh/g of the total charge capacity stored by the cell or battery, per gram of the battery’s weight.

Unfortunately, the large volume change of silicon during charge–discharge cycles has in the past weakened its competitiveness. Recently, however, a research group from Samsung reported in the publication Nature Communications that using direct graphene growth over silicon nanoparticles without silicon carbide formation resulted in a near doubling of run-time by expanding energy density– the amount of stored power in a given area — to 1.8 times that of current batteries.

Samsung Researchers Nearly Double Lithium-ion Battery Capacity – [Link]

Rohde & Schwarz HMC8043 PSU: Review and Teardown

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by Martin Cooke @ elektormagazine.com:

Bench power supplies aren’t really pieces of kit that get your pulse racing, they just sit there doing their job, in some cases giving gentle background heating to keep the lab warm in the winter and providing enough ballast to stop your bench wobbling about too much. The traditional bench top power supply always came with a sturdy handle on the top to give you a clue that inside is some serious ironwork and that this beast is going to be heavy. But that was all yesterday; buy a power supply today and it doesn’t look much different from any other piece of test gear; covered in buttons with a TFT display and the chances are you can wrap your hand around it and pick it up one-handed. That’s true of the HMC8043 three channel 100-watt bench power supply from Rohde & Schwarz I received for reviewing.

Rohde & Schwarz HMC8043 PSU: Review and Teardown – [Link]