Monthly Archives: February 2021

Homebrew Hakko 907 digital soldering station

via Arduino Blog

If you want to upgrade your soldering setup without spending a lot of money, then be sure to check out Angelo AKA TechBuilder’s DIY Hakko 907 station

This low-cost device features an Arduino Nano to read the iron temperature via an LM358 op-amp, and regulates power to the handle and tip under PWM control using an IRFZ44N MOSFET. A potentiometer is implemented as a variable temperature knob, with the actual and preset temperature displayed on a 16×2 LCD screen, while an LED indicates whether the heating element is active. 

Everything is encased in a nicely printed and painted enclosure, which forms a brilliant little station that one could be proud to use. Full build instructions can be found here, including the PCB, code, and print files.

App note: Virtually increasing the number of serial communication peripherals in STM32 applications

via Dangerous Prototypes

App note from STMicroelectronics on possible alternate switching of channels to cater multiple communication routes. Link here (PDF)

Application engineers often face the problem of limited number of serial communication peripherals of a microcontroller that, on the other hand fulfills all the other application requirements thanks to its features and performance. Sometimes they obviate by switching to a higher level microcontroller with sufficient number of communication peripherals. This migration brings with it additional (often unused) performance and functionality, in most cases unneeded and not used by application, in addition to increased costs and PCB complexity.
A frequent case is when full (or specific) functionality is not required for each and every channel, in this case the communication flow and its control can be simplified radically (e.g. communication is required at specific modes or time slots only, communication speed can be lower, correct timing is not strictly required for all the signals, simplified protocol or flow is acceptable). In these specific cases the user would really benefit from methods on how to supplement the missing channel(s) with current HW, to avoid needless migrations.

Name that Ware, February 2021

via Hacking – bunnie's blog

The Ware for February 2021 is shown below.

This one’s a bit tougher, since it’s just a small section of the complete circuit board; but I think there’s enough visible to have a stab at what the core function might be of the circuits highlighted here! Should be an interesting stumper.

Thanks again to Don Straney for contributing these wonderful wares!

Winner, Name that Ware January 2021

via Hacking – bunnie's blog

The Ware for January 2021 is a LogiMetrics 921A RF signal generator. Or at least, that’s what the caption says on the picture that was sent to me; the insides don’t quite match up with other photos on the Internet, but it also seems there were a few revisions of the equipment over time, plus various enthusiasts have taken it upon themselves to overhaul their devices before passing them on to a new owner.

I’ll give the prize to Allen Smith for being the first to roughly identify the gear category and vintage. Congrats, email me for your prize!

I really love the classic, air-gap variable capacitor on this device. It’s exactly what I would want on hand to illustrate how capacitors work in an entry-level electronics class…if I had an infinite budget.

App note: Power transistor safe operating area – special considerations for switching power supplies

via Dangerous Prototypes

App note from ON Semiconductors about less common transistors stresses when used on switching power supplies. Link here (PDF)

The power transistor, in today’s switching power supply, exists in an environment which is quite hostile to semiconductors. Large currents, large voltages, high temperature, high frequency, and low impedance sources add up to something close to the worst of all possible worlds for the transistor.
Given this type of environment, it is not surprising to find that keeping transistor stresses within acceptable limits can be quite a challenge. Transistors designed and specified specifically for switching power supplies help, but do not in themselves guarantee a reliable design. Very often, reliability is determined by the more subtle aspects of how stress imposed by the power supply relates to transistor safe operating area.

Monitor your hoverboard’s power draw with this Arduino-based meter/logger

via Arduino Blog

If you look at your car’s dashboard, there’s a good chance you’ll find an efficiency rating for how you’re driving. However, what if you instead ride a hoverboard? This functionality is certainly not stock equipment, yet Niklas Roy wanted to understand the power consumption of his transporter during different riding situations. For that reason, he decided to develop a power monitor that not only graphs his stats when scooting around, but records the data for later viewing and analysis.

Roy’s handheld device is controlled by an Arduino Nano and utilizes a Hall effect ammeter for current sensing. The measurements are shown as numbers and as oscillograms on a 1.8” TFT screen, which can also be logged to the display’s built-in SD card. An RTC module provides timestamp information for these readings, which can be produced using Processing and overlaid on video.

More details can be found on Roy’s GitHub page.