DIY Electronics and Hardware

If you’ve got an old black and white TV, it’s probably not useful for much. There are precious few analog broadcasters left in the world and black and white isn’t that fun to watch, anyway. However, with a little work, you could repurpose that old tube as a clock, as [mircemk] demonstrates.

The build is based around an Arduino Nano R3. This isn’t a particularly powerful microcontroller board, but it’s good enough to run the classic TVOut library. This library lets you generate composite video on an Atmel AVR microcontroller with an absolute minimum of supporting circuitry. [mircemk] paired the Arduino with a DS3231 real-time clock, and whipped up code to display the time and date on the composite video output. He then also demonstrates how to hack the signal into an old TV that doesn’t have a specific input for composite signals.

Instructables link

Designed by Nova Radio Labs in the US, the Novaduino Environmental Sensor Kit is an Arduino-programmable air quality and weather monitoring solution built around the company’s own Novaduino Display Module. It provides VOCs, eCO₂, temperature, humidity, and barometric pressure data in real time, making it ideal for Smart Home experiments, classroom projects, or hobby weather-station builds.

The kit integrates a Sciosense ENS160 air-quality sensor and Bosch BME280 environmental sensor connected via Qwiic, which measures TVOCs, eCO₂, temperature, humidity, and pressure with an on-device AQI indicator. It includes the Novaduino display PCBA, 2.4-inch IPS touchscreen, buttons, rotary encoder, Feather M0 Express or RP2040 module support, headers, mechanical hardware, and optional 3D-printable enclosures (STL/F3D/STP). Designed for learning soldering, assembly, and Arduino programming, the kit is uncalibrated and intended for educational and experimental use only.

A project I keep thinking about for my kitchen when I get it done up is an approximate clock display, so an eink display showing something like

https://kenlim.github.io/pyWordyClock/

Or similar. I guess the latter running on a Pi of some description.

I would be new to most of this, can anyone point me to a good way of getting started?

Over on YouTube [DENKI OTAKU] runs us through how a 4-pin MOSFET works and what the extra Kelvin source pin does.

A typical MOSFET might come in a 3-pin TO-247 package, but there are 4-pin variants which include an extra pin for the Kelvin source, also known as source sense. These 4-pin packages are known as TO-247-4. The fourth pin provides an additional source for gate current return which can in turn lessen the effect of parasitic inductance on the gate-source when switching current, particularly at high speed.

cross-posted from: https://programming.dev/post/38688621

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I'm a very impatient man. I want my tea at a drinkable temperature immediately.

It's a Panasonic BQ-390 AA charger, which used to be renowned as the best "smartest" AA charger.

The addon is an ESP32C3 with a 96x64 color OLED display, and an ADS1115 ADC.

The flashing dots indicate which cell is currently charging, as the charger only gives 0.5A to one cell at a time. The delay in voltage display is due to smoothing and filtering out stray voltage readings.

It can be powered either from the 5v regulator coming from the AA charger itself, or external USB power using a switch - the regulator in the charger isn't strong enough for the ESP32C3 to connect to wifi, so if I want to track charging status over wifi, I have to give it the extra USB power.

I got a lot of help from this ancient Japanese blog post I found of someone else who did a similar thing to the same charger:

http://act-ele.c.ooco.jp/jisaku/BQ390/bq390.htm