Devices I’ve Built
Here I put the descriptions of the devices I have built. Some of my software projects are on GitHub.
There are 19 articles in this section:
The HF transceiver I couldn't finish
As a teenager, I attempted to build a 0–30 MHz transceiver from scratch, going through three design iterations. None were completed; design errors and the lack of more advanced RF measurement equipment overwhelmed me. Still, I include the description here as a monument to that fascination.
Isolated power supply and 230 V testing station
I describe the design and construction of an isolated AC/DC power supply and testing station built from a salvaged East German variac. It features variable AC output (0–330 V) and DC output (0–450 V) and integrates digital meters and safety features.
Server resetter from Waveshare Ethernet Relay module
A quick project connecting a Waveshare Modbus Ethernet relay module to a motherboard's reset pin to have an emergency remote reset button.
Octoglow VFD - Fallout-inspired post-apocalyptic display
The project mixes modern technologies with obsolete ones like vacuum tubes and germanium transistors. Basically, it is an informational display heavily inspired by Fallout games that you can put on your desktop. I describe the solutions in detail.
28/29″ unicycle with handlebars and a brake
I modified a cheap 20-inch unicycle to fit a 29-inch wheel. I also added handlebars and a brake. This way, I created a contraption that you can ride quite comfortably for several kilometers.
Modernizing Belkin KVM console with HDMI and USB
I modified the 17″ Belkin OmniView 1U Rack-Mount Console to have USB and HDMI inputs instead of traditional VGA and PS/2.
UPS setup with APC Smart-UPS and car batteries
I connected a server-grade UPS to four car batteries to create a low-cost solution that keeps a server rack cabinet running for over 12 hours in the event of a power outage.
Automatic USB mains switch for power strip
Almost all available USB-controlled power strips simply use 5 V from USB to drive the relay. This is of no use with recent PCs, which keep 5 V enabled during sleep mode. I wrote alternative firmware for the popular DCT Tech USB relay module available from AliExpress, which detects bus inactivity and shuts the relay down when the PC is in sleep mode.
Hijacking Microlab speaker IR remote
I use Digispark module to inject NEC infrared protocol commands to start Microlab 6C speakers and select sound source automatically at startup.
Paramotor helmet with headset
Skateboard helmet, accompanied by Peltor earmuffs and communication equipment, is a legitimate alternative to expensive off-the-shelf paramotor helmets, which are, in fact, built on the same principle. I use a military-grade differential dynamic microphone to achieve superior speech intelligibility.
Cheap flight computer with Kobo Mini and BlueFly Vario
Using e-book reader Kobo Mini with BlueFly Vario is a cost-effective alternative to off-the-shelf paragliding variometers. I built one with a custom 3D-printed case.
Car radio shutoff delay
A simple circuit to keep the radio on for a few seconds after the ignition is turned off. This prevents the radio from shutting down when you want to restart the car.
Quick and dirty build of an SP6SYV antenna tuner
When the opportunity to get into amateur radio arrived, I built a variant of the Z-match antenna tuner, known in Poland as the SP6SYV antenna tuner.
High voltage generator 2.0
A high voltage generator built from two salvaged car ignition coils connected in antiparallel, driven by a CMOS 4011 pulse generator and an IRF740 MOSFET switching 30 V DC. Produces sparks up to 4 cm.
Small mobile robot controlled by IR TV remote
A three-wheel robot controlled by an IR TV remote controller and optionally, an RS-232 port. The motors are taken from old 5.25″ floppy drives.
Analog signal recorder for serial port
Single-channel signal recorder based on analog-to-digital converter TLC549, connected to the computer using serial port (RS-232).
Simple single-stage coilgun
An experimental Gauss gun I built during my teenage years that uses a magnetic field generated by the coil to accelerate the projectile.
Blasting machine made from an old military field phone
Pyrotechnic blasting machine made of an old military field phone for safe launching rockets and fireworks.
Linux PC-controlled model crane
A model crane with two stepper-motor axes and an electromagnet, driven from a PC parallel port. Comes with a text-mode controller written in C and a Tcl/Tk network client.