Measure small LCs with a scope

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Here is a simple way to measure an unknown inductance by forming a resonance LC circuit and measure it using an oscilloscope. Glen Chenier writes:

One of our technicians recently asked for help determining the value of an SMT inductor. It was unmarked, and was many turns of very fine wire on a ferrite core. The resistance measured 26Ω, which for some reason gave our ancient LCR bridge a conniption, and read 30mH along with a blinking error message. The tech rightfully felt that such a small inductor could not possibly be 30mH.

Measure small LCs with a scope – [Link]

Measure Stress Levels Using a Smartphone

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Researchers have developed a smartphone device that measures the cortisol concentration in saliva in order to define your stress levels. The new test is done in under 10 minutes and there is no need to send a salvina sample on a lab. The cost for each measurement is less than 5$ and the smartphone uses its camera and flash to take a picture of the saliva-coated strip and an algorithm converts the image’s pixel density to a cortisol value.

We have developed a method for measuring cortisol in saliva using a smartphone and a disposable test strip. This innovation enables anyone with a smartphone to measure their salivary cortisol level quickly, accurately, and affordably,

Measure Stress Levels Using a Smartphone – [Link]

A biometric sensor for wearables – LG Innotek

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LG Innotek has released an ultra-thin optical biometric sensor module designed to be used in wearables and smartphones to measure health parameters such as heartbeat, stress indicators and blood oxygen saturation level. The new sensor is more accurate than it’s predecessors achieving ±5 bpm range of error and consumes very little power to operate. At stable heartbeat rate an accuracy of ±2 bpm can be achieved, which is as good as conventional medical instruments. The module is just 1 mm thick and contains a photodiode, five LEDs and an IC.

A biometric sensor for wearables – LG Innotek – [Link]

SolarBoost – Make Your Own USB Solar Mobile Charger

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SolarBoost is an open source smart interface that allows you to build your own powerful and portable solar charger for your phone and other mobile devices. It has two USB ports and can provide 5V @ 2A at each of them and is controlled by a 8-bit 32MHz Microchip PIC microcontroller. It is also equipped with various protection features like soft-start, over-temperature, over-charge, over-discharge, short-circuit and current limiter.

SolarBoost is the first open-hardware and open-source smart interface designed to give you the freedom and flexibility to make your own battery- and solar-powered power bank for charging cellphones, tablets, MP3 players, speakers, GPS navigators, and much more. Use it to also power your DIY electronics projects!

SolarBoost – Make Your Own USB Solar Mobile Charger – [Link]

UP/DOWN counter with memory using PIC16F88

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Here is an up-down counter based on PIC16F88 and 7-segment display. The counter is using SMD components and features a RS-232 interface.

This is a simple digital counter with a serial rs-232 and a 7 segment display, i started this project to count items on some shelfs, but it can be used for anything, it is also, for the exception of the connectors, completely on SMD components.

UP/DOWN counter with memory using PIC16F88 – [Link]

Choose the right step-up/down voltage regulator for portable applications

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Reno Rossetti & Inyong Kim discuss about the power needs on portable devices and help us choose the right regulator.

A popular power source for portable devices is a single lithium-ion cell with 4.2V at full charge and 2.8V at end of discharge. However, some functions within portable electronics, such as a SIM card and DSP, require 2.8V and 3.3V. These are normally provided by low noise LDOs. The LDOs inputs (VCC) must be at a slightly higher voltage than the highest LDO output. Hence, VCC ends up right in the middle of the lithium-ion battery’s range of operation.

Choose the right step-up/down voltage regulator for portable applications – [Link]

LTC7813 – Low IQ, 60V Synchronous Boost+Buck Controller

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Linear Technology Corporation introduces the LTC7813, a dual output (boost + buck), low quiescent current synchronous DC/DC controller. When cascaded, its independent step-up (boost) and step-down (buck) controllers regulate the output voltage from an input voltage that can be above, below, or equal to the output voltage, including during an automotive load dump or cold crank. Unlike conventional single inductor buck-boost regulators, the LTC7813’s cascaded boost + buck solution provides fast transient response with continuous, non-pulsating input and output currents. It substantially reduces ripple voltage and EMI, ideal for automotive, industrial and high power battery operated systems.

LTC7813 – Low IQ, 60V Synchronous Boost+Buck Controller – [Link]

Open-source microprocessor

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Fabio Bergamin @ phys.org writes about PULPino which is an open source processor to be used on wearables and IoT.

In future, it will be easier and cheaper for developers at universities and SMEs to build wearable microelectronic devices and chips for the internet of things, thanks to the PULPino open-source processor, which has been developed at ETH Zurich and the University of Bologna.

Open-source microprocessor – [Link]

Nanocounter: Frequency Counter with an Android Interface

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Andy published his accurate and open source frequency counter that uses an Android phone as a display. It’s based on a high accuracy temperature compensated crystal oscillator (TCXO) fed into a phase locked loop (PLL) to create a high frequency reference clock. The reference clock along with the input signal is processed by a Xilinx FPGA and a STM32F072 mcu is reading the data.

Here we have a good example of how a requirement for a simple tool spirals out of control and spawns a project that takes months to complete and ends up dwarfing the project that it was originally expected to facilitate. You see, some time ago I was fiddling around with a project, something to do with data logging, probably, I’ve actually forgotten what I was up to.

Nanocounter: Frequency Counter with an Android Interface – [Link]