Using Low Cost Hardware to Enhance the User Experience

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Ken Boak discuss how to build a graphic user interface using cheap TFT toughscreen displays. This article is about using their lowcost graphics co-processor IC to provide a neat user interface for any low-end microcontroller.

These days, when you can buy a 7″ tablet for $50, there is all the more reason for makers and hackers to want to become more engaged with up to the minute 7″ touchscreen technology for their latest projects. Fortunately, recent developments in hardware have made this both affordable and easy to do – to the point where no project is too small, not have a neat touchscreen interface – and sound too!

Using Low Cost Hardware to Enhance the User Experience – [Link]

Generating Analog Voltage with Digital Circuit

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Maurizio show us how to generate an analog voltage using a microcontroller and some resistors.

The purpose of this article is how to generate analog voltage with digital circuit. Although the market provides today a very broad range of dedicated digital-to-analogue converters, putting such a device in the schematic has a negative impact on the overall cost of the system. There are however, cheap methods of creating the required voltage levels, and even of generating pseudo-analogue signals, using purely digital means.

Generating Analog Voltage with Digital Circuit – [Link]

Arduino Auto Power off. Make Arduino power off itself!

In this video educ8s.tv show us how to make Arduino power off itself with the help of a simple circuit!

If you have watched some of my previous videos you will know that I like my projects to have minimal power consumption so that we can use them with batteries for a long period of time. One of the biggest disadvantages of the Arduino boards is that they need a lot of current even when in idle state. This Arduino Uno board for example needs about 40mA when idle and about 20mA if we put the Atmega chip to sleep. That’s a lot of power, so, it will deplete any battery in a few days. So, I wanted a circuit that will let Arduino to turn off itself instead of putting it to sleep in order to conserve power. After a lot of experimentation and googling I finished a first basic version of this circuit. Let’s see it action.

Arduino Auto Power off. Make Arduino power off itself! – [Link]

An almost-GHz active differential oscilloscope probe

 

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Christer wanted to see how a 500MHz differential clock was behaving so he decided to build an active probe. To simulate the circuit he used TINA spice software and documented the process in three parts on his website.

What I really wanted was an active differential probe which should be able to look at a 500MHz signal at a couple of volts or so with decent fidelity. To do that I wanted a probe with about one GHz of usable bandwidth. I have an old Tektronix 11801B scope with two 20 GHz sampling heads with 50Ω single ended inputs that can handle signals which are 1.0V peak-to-peak so that’s what I wanted the probe output to be compatible with. The probe must attenuate the signal so to not overdrive the inputs and to make things easy to calculate I decided on letting the probe have a 1:10 attenuation.

An almost-GHz active differential oscilloscope probe – [Link]

Easy Arduino Menus for Rotary Encoders

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SimonM83 has posted a new tutorial on how to implement an Arduino menu using a rotary encoder. The tutorial goes through the hardware setup and sample code is provided.

Rotary encoders with centre-push buttons are cool input hardware for projects, especially if you want to be able to scroll through menus and select options. Hopefully this Instructable will give you the confidence to try a basic menu system out and combine it with a rotary encoder to give a professional feel to your next project!

Easy Arduino Menus for Rotary Encoders – [Link]

RELATED POSTS

Polyphonic Synth Cable

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Polyphonic MIDI Synth on an ATtiny2313:

This is the fourth synthesizer cable I’ve built, the first three being based on the ATtiny85. I have been looking into ARM chips but haven’t gotten to grips with them just yet. Instead, I decided go back to the ATtiny2313, which has a quarter of the memories of the tiny85, but a hardware UART port and more pins.

Polyphonic Synth Cable – [Link]

RELATED POSTS

Elektor 500ppm LCR meter case tips

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NopHead wrote a review of Elektor 500ppm LCR meter:

I recently bought a 500ppm LCR meter from Elektor because I didn’t have anything for measuring inductors or the ESR (equivalent series resistance) of capacitors, both of which are important for modern electronics, particularly switch mode regulators that have become ubiquitous. It is also more accurate than any of my multimeters and has wider measurement ranges.

Elektor 500ppm LCR meter case tips – [Link]

Android app turns smartphones into a seismic network

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Researchers at UC Berkeley (California) have developed an Android app that can detect vibrations from earthquakes using the standard sensors integrated into smartphones.

Android app turns smartphones into a seismic network – [Link]

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]