A software only solution to the vexing beagle bone black PHY issue


Josh Levine has a nice write-up about a software only workaround for the Beagle Bone Black PHY issue:

Sometimes the Ethernet port on a Beagle Bone Black does not work on power up. It takes either a physical reset button press or a power cycle to fix it. This problem affects all BBB’s and until now could only be solved with hardware hacks.

The final official word from TI on this problem:
“There is no solution for this on the BB Black“

Full details at josh.com.

Tutorial: Setting up a low cost QRP (FT8, JT9, WSPR etc) monitoring station with an RTL-SDR v3 and Raspberry pi 3


A detailed tutorial on how to set up a cheap QRP monitoring station using an RTL-SDR V3 and a Raspberry Pi 3 from rtl-sdr.com

This tutorial is inspired by dg0opk’s videos and blog post on monitoring QRP with single board computers. We’ll show you how to set up a super cheap QRP monitoring station using an RTL-SDR V3 and a Raspberry Pi 3. The total cost should be about US $56 ($21 for the RTL-SDR V3, and $35 for the Pi 3).
With this setup you’ll be able to continuously monitor multiple modes within the same band simultaneously (e.g. monitor 20 meter FT8, JT65+JT9 and WSPR all on one dongle at the same time). The method for creating multiple channels in Linux may also be useful for other applications. If you happen to have an upconverter or a better SDR to dedicate to monitoring such as an SDRplay or an Airspy HF+, then this can substitute for the RTL-SDR V3 as well.

More details at rtl-sdr.com.

Bit-bang FTDI USB-to-serial converters to drive SPI devices


Scott W Harden writes , “The FT232 USB-to-serial converter is one of the most commonly-used methods of adding USB functionality to small projects, but recently I found that these chips are capable of sending more than just serial signals. With some creative programming, individual output pins can be big-banged to emulate a clock, data, and chip select line to control SPI devices.
This post shares some of the techniques I use to bit-bang SPI with FTDI devices, and some of perks (and quirks) of using FTDI chips to bit-bang data from a USB port. ”

See the full post on Scott Harden’s blog .

Check out the video after the break


An easy way to mount DS18B20 temperature sensors


Matt wrote an article describing a technique he used to mount DS18B20 temperature sensors:

One of the biggest advantage of these sensors over I2C sensors, is that you can mount them almost anywhere. That having been said, I’ve never quite managed to come up with an elegant solution, particularly when attaching to a heatsink (for cooling applications)

More details at Matt’s Tech Pages.



ETA Nixie tube clock

ETA Nixie Tube Clock-600

Mark Smith over at surfncircuits has a nice write-up about building an ETA Nixie Tube Clock:

This DIY project will combine the estimated time of arrival function with a Nixie tube display to create an estimated time of arrival (ETA) Nixie tube clock. It is all easily controlled by a Raspberry Pi Zero W that is connected to the internet through WiFi to provide the latest time and gets the ETA for any number of destinations. The travel time is provided by the free Google Directions API interface that includes traffic to give the best estimates on any particular day.   The goal is that with an ETA Nixie tube clock, no math is needed to add a rough, often optimistic travel time, to the actual time to determine if we are running late.   The clock does that for you and with the power of IOT, is much more accurate!    A motion sensor is also added to the clock to turn off the Nixie Tube Display when no one is around, saving power and increasing the Nixie tube lifetime.

Build log at www.surfncircuits.com. Project files are located at Github.

Arduino time attendance system with RFID


A how-to on building a time attendance system with MFRC522 RFID Reader and Arduino from Random Nerd Tutorials:

Before getting started it’s important to layout the project main features:
*It contains an RFID reader that reads RFID tags;
*Our setup has a real time clock module to keep track of time;
*When the RFID reader reads an RFID tag, it saves the current time and the UID of the tag in an SD card;
*The Arduino communicates with the SD card using an SD card module;
*You can set a check in time to compare if you are in time or late;
*If you are on time, a green LED lights up, if you are late, a red LED lights up;
*The system also has a buzzer that beeps when a tag is read.

More details at randomnerdtutorials.com.

Check out the video after the break.

How not to build a semiconductor lapping machine

electronupdate writes:

One area of silicon reverse engineering which has interested me is the delayering of a chip to see each layer which allows superior visibility into the circuitry. I know of two ways: chemical etch and mechanical means.
In this video I try to make a mechanical grinder which can take micron levels of material away: a partial success. Parts are ground but I was not able to keep the silicon absolutely flat. More study of the commercial units is warranted!

See the full post on electronupdate blog.

DIY Moteino guide


Felix writes, “I posted a short illustrated guide for making your own Moteino from SMD components. It also includes details how to burn the bootloader and fuses. Check it out here. Thanks and credit goes to forum user LukaQ for his contribution of the images and test sketches in this guide!

See the full post at LowPowerLab.

Negative impedance converters


An article discusses the negative resistance and negative impedance converter from Analog Zoo:

“Negative resistance” may seem like a purely academic concept, but can be easily realized in practice with a handful of common components. By adding a single resistor to a standard non-inverting op amp circuit, we can create a negative impedance converter, which has applications in load cancellation, oscillator circuits, and more.

More details at Analogzoo.com.

Check out the video after the break.

Why electrolytic capacitors are actually kinda shitty


Afroman writes, “Electrolytic capacitors are common, but knowledge of their limitations is uncommon. A demonstration is shown highlighting the difference in performance between electrolytic and ceramic capacitors in power supplies. Other topics discussed in the video: Electrolytic capacitor construction, ceramic capacitors, ESR, ESL, impedance curves, why “0.1uF”, and more.”

Via Afrotechmods.

Check out the video after the break.