This is a development of this prototype: The goal was to turn the prototype into a highly reproducible device that could be tested in a real ham shack by operators who wouldn’t have to change their radio setup (or their aesthetic taste) to accommodate the new gadget. It is also expected to serve as a…
This project is based on my original schematic from the year 2005, when I also built and tested a perfboard prototype. I didn’t think much of it then, but, at least on the Internet, it has since become an exemplary circuit for the “passive Ethernet hub” in general. I’ve seen it featured in the prior…
What this device does: as soon as you change the band on your HF radio, the antenna is automatically changed accordingly. Since there are more HF bands than available antennas, the antenna layout – which antenna to use on each HF band – is determined by DIP switches. I did consider developing a simple Android…
I have been using a talking multimeter for years, almost every day, and I find it extremely convenient and useful. I am continually surprised that they are not in use everywhere. However, the Arduino part of my old design works with only a handful of multimeter models. This new prototype uses the SCPI communication protocol,…
Any beginner can build this from components that can be found in an electronics scrap heap or are at least inexpensive. Yet, this device is both an interesting demonstration piece and a practical tool because it relies on cool physical principles to provide a useful function. When used with a radio receiver, it can determine…
A weekend experiment… I have never worked with Arduino Zero or its derivatives before. This SAMD21 board is from Aliexpress. It has the native USB port only and in at least one instance its PCB layout seems to be at odds with the Arduino IDE files describing Arduino Zero (see program comments). Still – it…
After you finish reading this article, please also read the sequel: This real-time Morse decoder uses the Goertzel algorithm to detect a CW tone of 708 Hz. In order to better isolate the useful signal, the program introduces comparing the magnitudes for three frequency bins – the central one and two adjacent ones on both…
Ovaj štit omogućava da se na Arduino Uno (ili Arduino Mega) lako povežu Bluetooth modul za serijsku komunikaciju i OLED displej. Na sam štit mogu se direktno umetnuti displeji širine do 27,4 mm (1,08 inča). Bluetooth modul može biti klasični HC-05, HC-06, ili noviji JDY-31, JDY-33, DX-BT04-E itd, već u skladu s potrebama projekta. Sami…
This shield was designed with no particular project in mind. It aims to be useful for both automatic and keypad-operated antenna selectors in general. This is just hardware, providing slightly more than a set of ten relay drivers, but there are many projects/sketches on the Internet (including this blog) that could be easily adapted to…
An interesting find on Aliexpress: a slightly larger Arduino Nano board with an in-built 0.91″ OLED display, 128×32, I2C. The driver chip is the SSD1306. Three libraries were needed to set it up and test it with a new sketch, but it works OK now. It could come handy for debugging comms or for monitoring…