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

Just one of the many interesting articles written by Ken Shiriff, who also has chip photos together with detailed information about the corresponding circuit, e.g.
https://www.righto.com/2022/04/reverse-engineering-lm185-voltage.html

Mostly chip photographs. Found on Bunnie H's blog https://www.bunniestudios.com/blog/?p=6656

The MakerLisp Machine is a portable, modular computer system, designed to recapture the feel of classic computing, with modern hardware. The CPU is a Zilog eZ80 running at 50 MHz, which supports up to 16 MB of zero wait state RAM. The system software is 'MakerLisp', a 'Lisp on Bare Metal' system that allows direct access to system hardware, while providing the concise expressive power of a functionally complete Lisp environment. The machine is also an ideal platform for an extended CP/M. A full system configuration is pictured here, with CPU, expansion board, USB keyboard, and VGA display, in the laser-cut wood 'MakerStation' enclosure.
Found via the TUHS mailing list https://www.tuhs.org/pipermail/tuhs/2022-December/027035.html

Discussion about calibration of the local oscillator frequency of the bullseye LNB
https://github.com/g4eml/Bullseye-Calibrator

Open source hardware design for a Hardware Attached on Top (HAT) GNSS receiver based on Septentrio Mosaic modules.
Nice description of some circuit and layout details.

Spresense consists of a Arduino compatible board with Sony’s high performance CXD5602 micro-controller. The CXD5602 has built-in GNSS and high-resolution audio capabilities.

See also https://www.seeedstudio.com/re_computer