No SMD tools removal and soldering of QFP packages tutorial from Silicon labs. Link here (PDF)
This document is intended to help designers create their initial prototype systems using Silicon Lab’s TQFP and LQFP devices where surface mount assembly equipment is not readily available. This application note assumes that the reader has at least basic hand soldering skills for through-hole soldering. The example presented will be the removal, cleanup and replacement of a TQFP with 48 leads and 0.5 mm lead pitch.
There are different ways to ruin a Linux system. For the Raspberry Pi which uses a micro SD card as the storage device by default, it comes with two challenges:
1.Excessive writes to the SD card can wear it out
2.Sudden power failure during a SD card write can corrupt the file system
For problem one I do I have a mitigation strategy (see “Log2Ram: Extending SD Card Lifetime for Raspberry Pi LoRaWAN Gateway“). Problem two can occur by user error (“you shall not turn it off without a sudo poweroff!”) or with the event of a power outage or black out. So for that problem I wanted to build a UPS for the Raspberry Pi.
Johnson Davies shared detailed instructions of how to build an ATSAMD21-based computer on a prototyping board using a 32-pin ATSAMD21E:
If you’re looking for something more powerful than the ATmega328 in the Arduino Uno a good choice is the ATSAMD21. This is an ARM Cortex M0+ processor with up to 256KB flash memory, 32KB RAM, and a 48MHz clock, so it’s substantially better equipped than the ATmega328. In addition it has a USB interface built in, so there’s no need for a separate chip to interface to the serial port.
Arduino have designed several excellent boards based on the ATSAMD21, such as the Arduino Zero or smaller-format MKRZERO. However, these boards are an expensive way to use an ATSAMD21 as the basis for your own project, and they probably include many features you don’t need.
Dilshan Jayakody writes, “I tested a couple of TFA9842AJ based amplifiers in the last couple of years. The main reason I liked TFA9842AJ is its simple, clean design, wide operating voltage, and high-quality bass-rich audio output. Thanks to it’s built-in DC volume control circuit this audio amplifier can easily interface with MCU. In this article, we provide a generic TFA9842AJ module which works with most of Arduino boards, MCUs and SOCs.”
Boosting DAC’s output to drive larger voltage tackled in this app note from MAXIM Integrated. Link here (PDF)
Many modern systems have the majority of their electronics powered by 3.3V or lower, but must drive external loads with ±10V, a range that is still very common in industrial applications. There are digital to analog converters (DACs) available that can drive loads with ±10V swings, but there are reasons to use a 3.3V DAC and amplify the output voltage up to ±10V.
NXP Semiconductor’s implementation of Tire pressure monitor (TPM) system. Link here (PDF)
The Tire Pressure Monitoring System Reference Design consists of five modules: four tire modules and a receiver module. The tire modules consist of the MPXY80xx, the RF2, a battery, several discrete components, and a printed antenna. The receiver module has the MC33954, the KX8, five LEDs to display the status, a battery, a power supply connection, and an RS-232 serial interface.
In this post I will present a new hardware version of my sensor, older versions are described in part I and part II. In comparison to the previous one, sensitivity is roughly x10 more sensitive.
In previous version, tin foil window for photodiodes was very close to the BNC sockets and because enclosure was small, it was hard to place a sample close enough. Not it’s better, however, if I would choosing again, I would use metal enclosure similar to those used in PC oscilloscopes and put BNCs on front panel, power socket on rear panel and tin foil window on top. This would allow me to easier access for debugging- now I have to desolder sockets to get to photodiodes or to bottom side of PCB.
First, I decided to upgrade from the Raspberry Pi Model B to a more recent Raspberry Pi Zero W that I had on hand. Wired Ethernet is so ~ 2013 after all, and wireless would be a lot more convenient. Next, I designed a 3D printed case for it, as my old laser-cut-acrylic-and-glue case also looked very dated. Finally, I replaced the software with a new program designed to poll the data from my octoprint server. In less than an afternoon, I had turned the old temperature/humidity display into something useful.
Eric Higgins has a nice build log on his Open Trickler project a bluetooth-enabled smart powder trickler from off-the-shelf parts for under $60:
Fundamentally, this is not a hard problem to solve. Read the value from the scale, run a motor that moves powder into the scale, turn off the motor when the scale reads the target weight. As with many projects, the devil’s in the details and there was plenty of trial-and-error during the development process to reach a working prototype.
In this project, a Raspberry Pi is used to read the weight from the scale and run a small vibration motor (like those in mobile phones) to trickle powder. An app on your phone or tablet connects to the Raspberry Pi over Bluetooth, and is used to set the target weight and start/stop the automatic trickling process.
I just picked up a LogiMetrics A300/S 2 GHz to 4 GHz (S band) traveling wave tube amplifier (TWTA) on eBay. I had done an extreme teardown of an HP 493A TWTA a while ago and it was quite fascinating to see what’s inside of a TWT. This LogiMetrics A300/S was made from the late 70’s and unlike the HP 493A it was made entirely using solid state devices (e.g. transistors and ICs), the TWT itself of course remains a vacuum tube.