App note: Failure signature of electrical overstress on power MOSFETs

Nexperia app note about MOSFET’s destruction investigative hints that can be used for design improvements. Link here (PDF)

When Power MOSFETs fail, there is often extensive damage. Examination of the size and location of the burn mark, the failure signature, provides information about the type of fault condition which caused the failure. This document provides a catalogue of failure signatures from common electrical overstress failure modes. The catalogue can be used in forensic investigation of the underlying root cause of failure to improve module design and reliability.

App note: Designing in MOSFETs for safe and reliable gate-drive operation

This app note from Nexperia discuss’ gate drive designs for safe operation of MOSFET. link here (PDF)

The MOSFET gate-source threshold voltage (VGS-th) and maximum gate-source voltage (VGS-max) are key parameters that are critical to the reliable operation of MOSFETs. The threshold voltage represents the voltage at which the MOSFET starts to turn on, whilst the maximum gate-source voltage is the maximum gate-source voltage that the MOSFET can withstand safely. VGS-max ratings vary between suppliers and between MOSFETs, which can make it difficult to choose appropriate MOSFETs for the application.

24-bit stereo audio DAC for Raspberry Pi

Dilshan Jayakody has published a new build:

This project is about 24-bit stereo DAC, which we build for Raspberry Pi boards. This R-2R ladder DAC is developing around Intel / Altera EPM240T100C5N CPLD.
We developed this module after review the PT8211 DAC, which we tested a few months ago. Compare with PT8211 DAC, this module is capable to provide high-quality audio output with Raspbian OS.

See project details on Jayakody’s blog. Project files are available on GitHub.

Simple VU-meter circuit

VU-meter circuit built on a breadboard using transistors, diodes, resistors, and LEDs @ Build Electronic Circuits:

It’s basically a simple display for showing a value. It’s originally for showing signal level in audio circuits, but there’s no reason you can’t use it to show temperature, rain intensity, light level, or whatever other value you are measuring.

Check out the video after the break.

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App note: How to protect mobile devices from ‘USB Kill’ threats

Great read from Bourns about USB killer devices and port protection solutions. Link here (PDF)

Researchers have long warned about the security risks of inserting other users’ USB drives into your PC, even those from whom you trust. If the threat of malware infections isn’t cause enough for concern, there have been stories of malicious USB thumb drives that have “fried” laptops. Does this seem like a far-fetched occurrence? Hearing of the threats, PC World documented the work of an electronics engineer who set out to create a prototype that could actually kill a mobile device’s USB port.

App note: Protecting USB Type-C Cable connectors featuring higher power & tighter pin spacing

Bourns’ built-in thermal cut-off devices adds extra protection from faults directly on USB Type-C cables. Link here (PDF)

The now ubiquitous Universal Serial Bus (USB) standard was initially developed in 1994 with the intent of providing a communication standard to improve and simplify communication between the PC and peripheral devices. An updated version of the USB interface standard is the USB 3.1 Superspeed+, which doubles the data rate to 10 Gbps – a 2x improvement of the previous generation USB 3.0 Superspeed. USB 3.1 Superspeed+ is backwards compatible with USB 1.1, 2.0 and 3.0 with a power delivery projected at 100 W. This gives users enhanced data encoding for more efficient data transfer offering higher throughput and improved I/O power efficiency.

In addition to the increased power capability and bandwidth achieved in this updated USB standard, the connector has been changed. The original simple 4 pin D+/ D- Power and GND format has been upgraded and now combines multiple connector functions into one. The new USB Type-C connector features 24 pins in a smaller form factor.

A downside to this combination of increased power and the extremely tight pin spacing is heightened concern about potential safety and fire hazards due to the possibility of thermal runaway at the connector. To deal with these potential threats, it is recommended that electronic equipment manufacturers and connector and cable manufacturers integrate overcurrent and overtemperature protection into the Type-C connector.

FIREO – a low power SSB/CW tranceiver with its unique speech processing

Kang.K.P.S. writes:

“FIREO” (Pronounced FIRE-O), is basically a bit of non-conventional QRP (low power) SSB/CW transceiver design in which speech compression is implemented using FM limiter circuit. This unique approach of speech processing increases the effective average transmitted power and thus it improves on the signal strength reports at the receiving end. Consequently this technique also helps to cut through any man made or natural noise, very effectively.

See the full post on Small Wonder QRP blog.

Compact Si5351 based SDR

Ray Ring has written an article detailing the build of his mini SDR radio using FV-1 Audio processor and Si5351:

This is a revised version of my FV-1 based SDR. I replaced the CS2100 clk generator with the Si5351 clk generator. The Si5351 has some advantages over the CS2100, namely you can generate quadrature clks directly. This simplifies the hardware design and improves the quadrature accuracy. The sideband rejection in LSB/USB modes is impressive..somewhere around 60 db as best I can measure.

More details at circuitsalad.com.

Check the video after the break.

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An ATmega brushless sensored motor driver v02

David Gironi writes, “Brushless electric motor (BLDC motors) are synchronous motors that are powered by a DC electric source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor. Hall sensored motors uses hall effect sensors or a rotary encoder to directly measure the rotor’s position.

See the full post on David’s blog.

Check out the video after the break.

Continue reading “An ATmega brushless sensored motor driver v02”

App note: Offline non-isolated flyback converter protection

A white paper from Bourns about thermal protection PTCs on flyback converters. Link here (PDF)

This paper examines the use of resettable polymer fuses for protecting offline flyback converters. Using a thermal model of the resettable fuse surrounding solder pads and copper to optimize the trip time so that the converter is protected during overloads, there are two potential positions considered for polymer Positive Temperature Coefficient (PTC) resettable fuses in the circuit. One position is directly on the winding and the other position is beyond the control loop. Results are taken from the converter and compared with a simulation.

DIY cloud weather station with ESP32/ESP8266 (MySQL database and PHP)

A how-to on building cloud weather station with ESP32/ESP8266 @ Random Nerd Tutorials:

Build a cloud weather station dashboard to visualize your ESP32 or ESP8266 sensor readings from anywhere in the world. You’ll see your sensor data displayed on gauges and on a table. The ESP32 or ESP8266 will make an HTTP POST request to a PHP script to insert your data into a MySQL database.

See project details at randomnerdtutorials.com

Check out the video after the break.

Continue reading “DIY cloud weather station with ESP32/ESP8266 (MySQL database and PHP)”

Building an extremely high powered 1-12V lab power supply on the cheap

Matthew Millman has published a new build:

For a number of years now I’ve had a couple of high powered switching power supply units made by Power-One. They’re typically found in I.T. equipment and provide a single output rail of either 12 V or 48 V with a very high current rating. The other cool thing is that in the case of the 12 V model – the output voltage can be changed in software from 1 V to 12 V (12.45 V is the max). The 48 V model does not allow configuration of the output voltage frustratingly.

See the full project writeup on Matt’s Tech Pages.

Touch display with RGB silicone buttons for Bus Pirate Ultra

This is the prototype display board for the next, and possibly final, revision of Bus Pirate “Ultra” v1. We went a bit wild, but we’re thrilled at the possibilities:

  • 2.8″ IPS LCD with capacitive touch display. The capacitive touch sensor is I2C based, so we added an I2C bus and interrupt pin to the flex connector
  • 2 silicone buttons with an RGB LED under each. The buttons are read through a TCA9534 I2C IO expander, basically a 5volt tolerant PCF8574 at half the price. The TCA9534 uses the same I2C bus as the capacitive touch sensor, and gets a dedicated interrupt signal on the flex connector
  • SK9822 RGB LEDs share an SPI bus with the LCD. The SK9822 runs at 5volts and uses a two pin protocol that can be driven by an SPI peripheral, but it doesn’t have a chip select pin so it can’t share an SPI bus with other slaves. We use a 74HCT573 as a level converter (3.3->5volts), and the 573’s latch pin as a pseudo chip select
  • The board is now powered from VUSB (5volts) and has a 3.3volt regulator
  • 6 additional IOs (routing in progress) from the unused pins of the TCA9534

A few tweaks to the schematic before we send off the PCBs:
*MISO on SPI should be jumpered. This leaves a disconnected pin between VUSB (5volts) and the 3.3volt logic pins
*Route unused IO pins to a header
*Run LCD backlight from VUSB

v1e is nearly complete and we’ll make a small batch of them soon, but probably immediately after spring festival. Feels free to hit us up on Twitter or check out the latest in the forum.

App note: Layout recommendations for PCBs using a magnetometer sensor

Another app note from NXP on PCB design guidelines when using magnetic sensitive sensors. Link here (PDF)

Unlike accelerometer, pressure, and gyroscope MEMS sensors, which use mechanical sensing elements unaffected by electromagnetic components on the PCB, magnetometers are sensitive to the magnetic fields generated by other circuit components.
The most common magnetic field sources are:

• permanent ferromagnets (as found in speakers or buzzers)
• induced fields within any ferromagnetic material lacking a permanent field (such as sheet steel)
• fields generated by current flows (ranging from strong currents in power supply tracks to smaller currents within coils).

App note: Implement high-speed RS-485 application with i.MX RT based on NXP SDK

App note from NXP link here (PDF)

This application note describes how to implement RS-485 communication with NXP i.MX RT series EVK, and how to design software based on NXP MCUXpresso SDK. For high-speed RS-485 bus, normally the baud rate is up to 5 Mbps; the interrupt and software polling mode is not practical in such a scenario. DMA and other mechanisms must be adopted based on SDK API.

Automated weather satellite ground station

Here’s an automated weather satellite ground station project from Nootropicdesign, that is available on Github:

This project will show you how to create a fully automated ground station that will receive and decode NOAA weather satellite images and upload them to your own website served from an Amazon AWS S3 bucket. With this project you don’t need your own server or have to run your own website infrastructure. Have a look at my AWS site that is updated automatically all day long.

See the full project writeup on the Project Lab blog.