Category: Hardware

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Keyboard converter between a Zbrojovka Consul 262.5 terminal keyboard and a Videoton VDX 52600 terminal.

This is a multi-purpose converter that enables the two vintage devices to be used on their own (1. USB keyboard adapter, 2. keyboard emulator over serial) or together to form an honest VT52 terminal.

Status: Semi-finished.
Reading from the keyboard works. Writing to the terminal works. Though it is unreliable and I haven’t discovered all the keycodes that the terminal accepts.

Project page: https://git.dejvino.cz/dejvino/consul-vdx-term-keyboard-converter

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Replace the old electronics of your tapedeck with an mp3 player, all while keeping the retro controls working!

A conversion project that takes a beautiful piece of obsolete hardware and gives it a new life. The aim is to retain as much of the look and the controls as possible. Buttons still control the playback, turning the knobs impacts the sound. Yet there is a tiny MP3 player board that loads the music from a microSD card and the turning cassette reels are just for show.

Status: Finished.

Project page: https://git.dejvino.cz/dejvino/tapedeck-player

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Powering on many devices at once might trip a circuit breaker due to the initial surge. A slow-start power socket avoids this by introducing a delay for the grid to stabilize.

The device uses an MCU to gradually energize a strip of power sockets using relays. This way, the startup is more gentle and there is no need to manually connect and disconnect devices.

Status: Finished.

Project page: https://git.dejvino.cz/dejvino/slow-start-power-socket

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3D printable case for a Geiger Counter kit packing a battery, ON/OFF switches and a servo motor to display the measurement.

Enclosed is a “RadiationD-v1.1 (CAJOE)” Geiger Counter kit that does all the work. A standard power bank for an 18650 battery cell provides the power. An Arduino reads the radiation ticks and drives a servo motor to display a time-windowed value. Switches enable or disable 1) the whole system 2) the clicking sound 3) the servo display. The case is modeled in OpenSCAD with the battery and the servo parts of the case being optional.

Status: Finished.

Project page: https://git.dejvino.cz/dejvino/GeigerCounterEnclosure

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VT100 terminal using an ESP32, LK201 keyboard and a TV.

This is a conversion of a black & white mini TV into a serial terminal that can be hooked up to e.g. a Linux host computer. ESP32 generates the TV signal, emulates a VT100 terminal and interfaces with the keyboard. It uses an LK201 terminal keyboard (which is otherwise not suitable for modern computers anyway).

Status: Finished.

Project page: https://git.dejvino.cz/dejvino/video-terminal-revival

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Linux box with a loudspeaker and an emergency light to be used for TTS announcements and notifications.

If you want to set up very loud notifications for events or reminders, this is a great solution. Announcements can be submitted via MQTT or scheduled over SSH. They are then read out loud via TTS. The Human-Activity-Sensor (PIR module) makes sure the speaker is extra loud only when there are no humans around.

Status: Finished. Out of regular service.

Project page: https://git.dejvino.cz/dejvino/announcement-box

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OS for the PINE64’s PineTime smartwatch and a companion app for a phone.

Development unit connected to a PC

The PineTime smartwatch OS is built on Zephyr in C/C++. The companion app (for Linux, Android) is used to sync data to the smartwatch over Bluetooth.

Status: Incomplete. Abandoned.

Turns out building a whole ecosystem is quite challenging!

Project page:
– https://github.com/Dejvino/pinetime-hermes-firmware :: PineTime OS
– https://github.com/Dejvino/pinetime-hermes-companion :: Companion App
– https://github.com/Dejvino/pinetime-zephyr :: Zephyr for PineTime
– https://github.com/Dejvino/zephyr :: core Zephyr modifications

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Ebook reader firmware designed for LilyGO T5 v2.4 (ESP32 with 2.9″ eInk display).

LilyBook prototype

The goal was to create an ebook reader that would be very small, last a very long time on a single charge and you could read it while walking, without having your vision obstructed that much (to avoid bumping into stuff!). Given the small display can only show around 4 lines of text, it is easy to keep track of where you are in the book; no need to re-read paragraphs every time your eyes move back and forth between the reader and your surroundings.

I’ve successfully tested this on my commutes to work where I managed to read through e.g. the story of Dr. Jekyll and Mr. Hyde, using it in a public transport and while moving through (or rather with?) a crowd on some of our busy streets.

Status: Beta version done and working. Possible improvements could come in the future.

Project page: https://github.com/Dejvino/lilybook