So how to do CW on a homebrew SSB rig?


Pete Juliano, N6QW, has written an article on how to do CW on a homebrew SSB rig:

The Answer is Not a Flippant: Carefully!
Author’s note: A friend in VK4 land made an inquiry about CW operation. I find that 99.99% of my operating time is SSB. But others spend a greater time on the air using CW so why not share some info and data that I have stashed on my computer where a SSB rig can be made to work CW. This also open the possibility of filter switching for a more narrow pass band. With Arduino anything may be possible.

More details on Pete Juliano’s (N6QW) blog.

Tiny particle sensor node with decorative case


Lucky Resistor published a new build:

This article is about a small sensor node with a decorative case. It is based on the Raspberry Pi Zero W board with a custom sensor shield on top.
I publish all hardware files for a simple version of the sensor, so you should be able to build this kind of sensor nodes and use it to monitor anything you like. You can also extend/modify the design easily with additional sensors. Nevertheless, the case lid design is based around the Plantower PMSA003 particle sensor. It has all required air vents for this use.

More details on Lucky Resistor homepage.

App note: Linear regulator problem situations – Power supply does not start


App note from ROHM Semiconductor about various start up problem on 3 pins linear regulator. Link here (PDF)

Although linear regulators can be used to easily configure power supplies, the linear regulators may cause startup problems depending on the type of loads. This application note introduces cases where the power supplies do not start correctly in the linear regulators.

App note: Design considerations for a harsh industrial environment

Design Considerations for a Harsh Industrial Environment

This article discusses factors that influence the robustness of a circuit in a harsh environment, like you would find for industrial applications. The topics covered include ways to handle voltage transients and to protect against electrostatic discharge (ESD) and faults. Link here

Semiconductor (IC) robustness—what is the operating temperature range? How is high electrical noise handled? What about ESD and fault protection? These issues are not necessarily the first things that a design engineer thinks about when selecting an IC. Nonetheless, robustness is a key performance parameter for long-term operation and a reliable, reputable end product. This is especially true when designing a system for an industrial environment where harsh operating conditions are common. Industrial equipment can be exposed to a wide range of temperatures, high electrical noise on either the power-supply lines or data lines, and fault events like ESD or short circuits.

Remote debugging with USB based JTAG/SWD debug probes


Erich Styger wrote an article on how to turn a USB debug probe into a IP-based debug solution:

For some projects it is not possible to have the device under debug available on my desk: the board might be in another room, on another site or in a place where physical access is not possible or even dangerous. In that case an IP-based debug probe (see Debugging ARM Cores with IP based Debug Probes and Eclipse) is very useful: as long as I can access its IP address, that works fine. It is an excellent solution even if the board is moving or rotating: hook it up to a WLAN access point and I still can use it as it would be on my desk.

More details on MCU on Eclipse homepage.

Experiments with a Hydrogen Thyratron


Kerry Wong did some experiments with a TGI1-50/5 hydrogen thyratron:

The one I picked up is a TGI1-50/5 hydrogen thyratron. As the name suggests, it uses ionized hydrogen gas as the switching medium. Hydrogen thyratron typically utilizes titanium hydride in it’s reservoir and the hydrogen gas is released when the reservoir is heated and recombined into titanium hydride when the temperature cools down. Like many other hydrogen thyratrons, the TGI1-50/5 has a separate heater for the hydrogen reservoir.

More details on Kerry Wong’s blog.

Check out the video after the break.

Raspberry Pi based indoor air quality monitor


Dr. Scott M. Baker made this Pi-based environmental monitor and wrote a post on his blog detailing its assembly:

For years I’ve followed the “uRadMonitor”, a device that does air quality monitoring and radiation monitoring. I’ve played with geiger counter projects before and frankly found them to be not very interesting. However, the idea of monitoring air quality is something that seemed like it might yield interesting data. For example, as I’ve started to become involved in 3D printing, it would be useful to see whether or not 3D printing affected the air quality. It would also be useful to correlate my results with what my region reports for outdoor air quality.

Check out the video after the break.

App note: MUX-friendly precision operational amplifiers


Another App note from Texas Instruments on op-amp input safety from breakdown voltages during source switch-over. Link here (PDF)

Multiplexing is a frequently used technique to perform data acquisition in multichannel systems with minimal signal-chain requirements. In this context, the role of the multiplexer (MUX) in an acquisition system is to switch between channels, and send each signal as quickly as possible to a single data converter, thus maximizing system throughput and minimizing delay. To provide accurate processing, a precision amplifier is placed downstream from the multiplexer to precisely drive the analog-to-digital converter (ADC).

App note: Precision current measurements on high-voltage powersupply rails


Two methods for measuring current and what sense amplifier used are tackled in this app note from Texas Instruments. Link here (PDF)

Current is a signal that can provide valuable insight into how a system is operating. Under defined conditions, the amount of current required to perform a task is consistent, making the current information a useful indicator to determine if the system is operating within expectations. There are multiple measurement methods and locations where current is measured to evaluate this informative signal.