An analogue frontend is available on https://store.fhdm.xyz/dso-500k

Badger 2040 is a programmable E Paper/eInk/EPD badge, powered by RP2040. Badger 2040 W is a programmable E Paper/eInk/EPD badge with 2.4GHz wireless connectivity, powered by Raspberry Pi Pico W. Both can go into a deep sleep mode between updates to preserve battery.

Hardware to emulate the SPI memory in PCs to speed up the development of free BIOS firmware.
Found on the Oberon mailing list.
See also the articles about retrocomputing and security, e.g. https://trmm.net/Cosign/

Controlling NeoPixel LEDs with a Raspberry pi Pico and Circuit Python.

The websites of the manufacturer Holux are no longer accessible. Holux users will not find any information, downloads (drivers, software etc.) or support at holux.com.
A former technician of Holux Germany and a former Holux specialist dealer are designing this free project. Holux users continue to receive detailed information about Holux GPS devices and support with questions or problems.

With UPS and RTC features, PiSugar2 makes your rpi ready for fast prototyping and product development.

The best compromise between sensitivity and portability
by Luca Feletti and Renato Romero. PCB layout by Jochen Richert.

Detailed description of a shielded magnetic loop antenna for VLF signals

The tinyPFA is a Phase Frequency Analyzer, it is a portable, battery operated, two input device with a 4 inch display that can measure very precise frequency and phase differences between the signals applied to both inputs. The input frequency can be any frequency between 1 MHz and 300 MHz. Typical use is to measure the differences between two 10 MHz clocks. The tinyPFA can numerically display the phase and frequency difference, show the measurement in a graph versus time, store the measurements on a SD card inserted into an SD card slot, or send the phase measurements over USB to a PC, running a program such as TimeLab, for further display and processing. Phase and Frequency measurement accuracy is better then 1e-12 divided by the measurement time in seconds with decimation set to 1 Be aware the maximum frequency difference that can be display depends on the measurement time (Tau) and is approximately 0.4 / (Tau in s) so for Tau is 1 s it is 0.4 Hz maximum difference.

Found on https://soldersmoke.blogspot.com/2017/05/indonesian-bitx-check-out-britx.html

Found on http://www.aaronsplace.co.uk/blog/2018-04-03-gpib-arduino.html