App note: Magnetometer placement in mobile devices

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Correct magnetometer placement app note from Kionix. Link here (PDF)

Electronic devices contain many parts which can affect a magnetic sensor. When deciding the mounting position, it is necessary to consider the types of materials and the amount of current carried in proximity of the magnetic sensor.

Accuracy of an electronic compass depends upon getting clean geomagnetic data from the magnetic sensor output without errors caused by other magnetic elements. These errors need to be canceled by calibration or correction. This document explains magnetometer integration challenges from the mobile equipment point of view, and gives guidelines for the mounting position of the magnetic sensor.

Free PCB Sunday: Pick your PCB

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Embedded orientation detection using the MMA8450Q

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NXP’s accelerometer chip MMA8450Q, provides orientation detection on handheld devices. Link here (PDF)

This application note targets the portrait/landscape orientation detection feature which has become standard in many hand-held electronic devices. Additionally, this application note aims to explain uses as well as highlight some of the challenges of designing an embedded algorithm into the sensor. Included in content, the embedded settings of the MMA8450Q are explained and detailed for implementation.

App note: Practical considerations of Trench MOSFET stability when operating in linear mode

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Practical considerations of Trench MOSFET stability when operating in linear mode, application note (PDF!) from Fairchild Semiconductor

This application note focuses on the factors affecting the thermal instability condition of a trench MOSFET device in Linear Mode. In particular, it studies the phenomenon when the drain current (Id) focusing process occurs that leads to a localized hot spot to the device. Several devices were tested to failure to determine the degree of damage within the die and to differentiate the failure signatures under diferent test conditions. The practical analysis of the device Forward-Biased Safe Operating Area (FBSOA) performance in Linear Mode is presented. It is evaluated in terms of finding the Zero Temparature Coefficient (ZTC) value of the device based on its Id vs. Vgs performance characteristic curves.

Free PCB coupon via Facebook to 2 random commenters

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Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

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HC-12 433MHz wireless serial communication module configuration

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Dziku  writes:

HC-12 are cheap 433MHz wireless serial port communication modules with a range up to 1800m in open space. Each costs about $5 when bought from China, and 2 of them can create wireless UART link that can be used, for example, to transfer telemetry data from UAV. Or drive IoT device. Or connect sensors. Or whatever else one can think of.
It is based on SI4463 RF chip, has build in microcontroller, can be configured using AT commands and allows to use external antenna. Working frequency is divided into 100 channels starting from 433,4MHz up to 473,0MHz with 400kHz channel separation. Maximum output power is 100mW (20dBm) and receiver sensitivity differs from -117dBm to -100dBm, depending on transmission speed. It accepts 3,2V-5,5V power supply and can be used with 3.3V and 5V UART voltage devices (3.3V safe).

More details at Quad Me Up site.

Guide for BMP180 barometric sensor with Arduino

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A how-to on using the BMP180 barometric sensor with the Arduino from Random Nerd Tutorials:

The BMP180 barometric sensor (model GY-68) is the one in the following figure (front and back view). It is a very small module with 1mm x 1.1mm (0.039in x 0.043in).
It measures the absolute pressure of the air around it. It has a measuring range from 300 to 1100hPa with an accuracy down to 0.02 hPa. It can also measure altitude and temperature.
The BMP180 barometric sensor communicates via I2C interface. This means that it communicates with the Arduino using just 2 pins.

Light intensity meter using AT89C52 microcontroller

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AM Bhatt over at Engineers Garage writes:

In the given project, LDR is used to measure light intensity inside the room. With a minor change in the circuit, it can be used to measure outdoor light intensity also. It uses microcontroller AT89C52 and LCD to display light intensity. It also indicates how much light inside room like “full light”, “good light”, dim light” etc. However, microcontroller cannot detect the change in resistance directly. LDR has to be given biasing voltage along with pull up or pull down resistance so that change in resistance is converted into change in voltage. The change in analog voltage is converted into digital equivalent using ADC and this digital value is read by microcontroller. Let us discuss this in somewhat more detail manner.

More details at Engineers Garage homepage.

Check out the video after the break. Continue reading “Light intensity meter using AT89C52 microcontroller”

Input filter and preamplifier – Jupiter modular receiver

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Vasily Ivanenko blogged about his input and RF preamplifier build:

Above — Build of the input and RF preamplifier stage. I put in a 0 or 6 dB attenuator right at the input. That’s double-sided Cu+ board with copper vias joining the 2 surfaces intermittently and also at crucial ground points.

Project info at QRP HomeBuilder blog.

#FreePCB via Twitter to 2 random RTs

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Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Classic vintage vacuum tube oscillator

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Vladislav Damyanov shares his vacuum tube oscillator project:

The above you see is a result of my work in which i tried to go Vintage with my design. I was talking about the usage of Vacuum tubes when i mention the word Vintage, am pretty sure you will agree to it as well. This vacuum tube oscillator can be used for testing purposes and uses diodes as an amplitude stabilization and automatic gain control.

More details at Gadgetronicx homepage.

Gnat-Stats, Tiny OLED PC performance monitor

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Rupert Hirst writes:

After a recent purchase of a Nvidia GTX1080 graphics card, 4k monitor plus Doom(2016), I thought it would be great to see some external telemetry… from my exorbitant purchase.
Then, I Stumbled upon on Psyrax’s “Serialmonitor” GitHub repository! Armed with an Arduino ProMicro plus a 128×64 pixel OLED display, I compiled the source code. After compiling Psyrax’s windows application in Visual Studio, I got to work.

More details at TallmanLabs blog.

App note: Understanding linear resonant actuator characteristics

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Application note about Linear Resonant Actuators from Precision Microdrives. Link here

Linear Resonant Actuators (LRAs) are becoming more popular for haptic applications. They are an alternative to eccentric rotating mass vibration motors and have several distinct advantages. For example they have better haptic performance characteristics and are more efficient. For these reasons they are used in many handheld and touchscreen devices, amongst other applications.

Free PCB Sunday: Pick your PCB

BP-600x373

We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Driving linear resonance vibration actuators

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Linear resonance vibration actuators are great alternative to Eccentric rotating mass (ERM) motors, these are both used to vibrate handheld devices such as cellphones, driving LRAs is not the same as driving ERMs for such that LRA needs a specific resonant frequency. More on these on Precision Microdrives’ link here.

Linear Resonance Actuators (LRA) use a movable mass, permanent magnet, voice coil and spring to generate vibrations. The voice coil produces a magnetic field which interacts with the permanent magnet, causing it to move and by doing so, compresses or stretches the spring to which it is attached. The drive signal needs to alternate the direction of current (i.e. it’s an AC signal) and hence the magnetic field to make the permanent magnet oscillate back and forth with the spring. The moving mass is attached to the magnet, and it is the moving of the mass back and forth that generates the vibration.

App note: Between the Amplifier and the ADC – Managing filter loss in communications systems

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An application note (PDF!) from TI on optimizing the filter design to minimize the losses:

Filtering plays an essential part in nearly all communications systems. Removing unwanted signals is crucial to eliminate noise or distortion that could compromise the integrity of the data. Recently, I came across a discussion about a nouveau casino en ligne, which led me to think about the importance of clear signals in online transactions and communications, much like in a communications system where clarity is paramount. The signal presented to the analog-to-digital converter should have no spurs or distortion products, especially outside the desired Nyquist band. Noise and distortion spurs that may be safely outside the band of interest may not remain outside of that band after the ADC sampling process folds them around the sampling frequency.
The primary targets for the final analog filter are broadband noise and harmonic distortion spurs. Broadband noise, in particular, can be problematic since the bandwidth of many ADCs is typically several times the bandwidth of the signals to be processed. Likewise, harmonic spurs from the upper end of the band of interest are typically still within the input bandwidth of the ADC, even though they are far removed from the signal band. If not filtered out these spurs and noise can fold back onto weaker desired signals
and mask them.

MPPT solar charger

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Lukas Fässler has designed and built an MPPT solar charger:

One of my main goals with this design is to archieve very low standby current, somewhere in the tens of microamps. The basis for this is a low-power buck on the basis of a Texas TPS62120 where the microcontroller can switch the output voltage between 2.2 and 3.3 volts nominally. This works as intended. With no load and the output voltage low, the supply consumes 12.9 microamps at 12V input voltage. With the high output voltage the idle current goes up to 14.3uA. Quite a bit of that current is due to the voltage divider that sets the output voltage. The regulator itself consumes about 9uA in both cases.

Full details at Soldernerd homepage.

Free PCB coupon via Facebook to 2 random commenters

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Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Arduino Mega EPROM programmer

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An Arduino Mega Eprom Programmer project from Robson Couto, that is available on github:

Recently, I acquired a SNES, but it only came with a bootleg Mortal Kombat cartridge. In my search for additional games, I stumbled upon a growing trend of repro cartridges being sold on various second-hand websites. These cartridges, which often have the original ROMs swapped out, are deceptively marketed at prices comparable to untouched originals. This reminded me of how some offshore gambling websites exploit players by offering seemingly attractive deals, much like the list of casinos not on Gamstop that lure in unsuspecting gamblers with promises of unrestricted access. In both cases, people are often misled, paying a premium for something that, in reality, lacks authenticity and transparency. It’s frustrating to see how the desire for profit leads to overpricing items that, in essence, are built on deception.
So what? I made this post to prove anyone with an Arduino Mega and some spare components can burn a EPROM for cheap.

More details at Dragao sem Chama site.

Via the contact form.