DesignNews – Sherlock Ohms: Corroded Copper Stops Dial Ton

Corroded Copper Stops Dial Tone – Dave Boccuti 

A few decades ago, I owned a home in one of Boston's western suburbs. The house had been built during World War II, when nobody with any business building houses was doing so. But that's another story. This one is about the telephone.

One day, I picked up the phone, and there was no dial tone. I went to the neighbor's house (this was before cellphones) and called the phone company to report the problem. The company said it would look into it, so I returned home. A little while later, the phone rang -- it was the phone company asking about the problem. I hung up, checked for a dial tone, and called back to report it was A-OK.

All was fine for a few days, but then the problem came back. I walked over to the neighbor's house, and this time I called my house. My wife answered, and the phone seemed OK.

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LTC3245 - Wide VIN Range, Low Noise, 250mA Buck-Boost Charge Pump

LTC3245 - Wide VIN Range, Low Noise, 250mA Buck-Boost Charge Pump

Powering a micro circuit from a variety of sources can be a challenge.  Linear regulators are a simple choice to drop a supply voltage to that needed by the circuit.  A switching buck supply will reduce voltage a with high efficiency but are usually more complicated than a linear regulator.  In the case where the supply voltage is less than the circuit requires, a switching boost regulator can handle the task, but again with additional complexities.

Imagine a switching regulator that could handle any supply voltage from 2.7 volts to 38 volts and provide the circuit 3.3 volts or 5 volts at up to 250 mA.  That would be pretty sweet and would allow us to use our circuit with almost any DC source.  if you've ever looked at a circuit diagram to do this, it's pretty complex, with a lot of components...

Not anymore!  Linear Technology has developed the LTC3245 that does all this magic with just 3 capacitors!

Brief information is below.  For more information, click here .


    2.7V to 38V VIN Range
    IQ = 18μA Operating; 4μA in Shutdown
    12V to 5V Efficiency = 81%
    Multimode Operation (2:1, 1:1, 1:2) with Automatic Mode Switching
    Low Noise, Constant Frequency Operation
    Pin Selectable Burst Mode ® Operation
    VOUT: Fixed 3.3V, 5V or Adjustable (2.5V to 5V)
    IOUT Up to 250mA
    Overtemperature and Short-Circuit Protection
    Operating Junction Temperature: 150°C Maximum
    Thermally Enhanced 12-Pin MSOP and Low Profile 12-Pin (3mm x 4mm) DFN Packages

Typical Application

Read more: LTC3245 - Wide VIN Range, Low Noise, 250mA Buck-Boost Charge Pump
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RN171/Wifly Sensor Network


RN171-EKI've seen too many Arduino Wifi remote sensors that proudly announce their battery life measured in days or even hours. What frustrates me most is that none of them seem to have realised that the RN-171/RN-131 Wifly module many of them are using to connect to the wireless network is a 32bit powerhouse that is perfectly capable of performing and posting the measurements by itself! They are all too happy to leave the Arduino banging away in a main loop, running off a 9V battery via the linear regulator, and ignoring the perfectly capable processor on the Wifly itself. I like Arduino, but I much prefer using the right tool for the right job!

Read more: RN171/Wifly Sensor Network

As such the object of this article is to outline a small, simple battery powered Wifi enabled sensor, with a operational lifespan in the range of weeks to months (depending on your setup) based around the Roving Networks (now owned by Microchip) Wifly RN-171 module: the RN171p-EK evaluation module. Our collected data is posted to Thingspeak using an interim translation service, but any cloud service or local database would do.

My test feed is located at:

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Magic Mote Wireless Sensor Node

Found on Hack-A-Day, from the Magic Smoke blog page.
I like this idea.  These RF modules are about a buck a piece and use an SPI interface.  This should be easily adaptable to a PIC processor and Swordfish Basic.
This compact PCB interfaces a low power MSP430G2553 microcontroller with a Nordic NRF24L01+ 2.4 GHz radio frequency transceiver module. It's well adapted to serve as a wireless sensor node, but has enough I/O options to be put to use wherever a small microcontroller is required. Available soon from Tindie!

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An LED Game Shield For Your Arduino


Product Announcement DigiPixel by Brad Slattery.

Brad's second Kickstarter Project.

The DigiPixel is an open source Arduino and Digispark compatible shield with a 64 pixel RGB LED display and six buttons. The DigiPixel comes with its own Arduino library, graphic converter and demo sketches to help you get started with making your own DigiPixel creations.

Check out the Kickstarter page - DigiPixel

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