RRDtool - quick tutorial

RRDtool is both a database and a graphing tool that is well-suited to visualize time-varying data like temperature, pressure and all kinds of telemetry.

There are many tutorials available, but they dig too much into the details (like the official one). Since I use RRDtool only for storing and graphing …

Banana Pi on battery power

The Banana Pi is a great alternative to the well-known Raspberry Pi. It is not a clone, nor a knock-off, rather a completely different, open single-board computer of a very similar size and good price. Most important features (compared to Raspi) to me are the 3 UARTs (one for the …

Small, cheap power supply modules from Aliexpress

I have recently bought a BananaPi with the intent of making a automotive datalogger. I needed a simple power supply that would work reliably in my car. I found some nice looking modules in "The Thick Electronic" store on Aliexpress.

This shop has many different DC/DC modules that can …

Universal antenna rotator controller

This is one of my older projects. I designed it for a friend of mine when he became fed up with his Rot1prog controller going bonkers all the time. I wanted it to be something as simple as possible, but still doing its job, easy to use and easy to …

NodeMCU as a standalone thermometer

I finally completed work on my networked thermometer. I got some old 7Ah 5-cell NiCd battery packs from emergency lighting fixtures that will power the device. I wonder how long can they last. NiCd batteries suffer from high self-discharge rates, on the other hand the NodeMCU will sleep most of …

B6AC battery charger teardown

I recently got some discarded NiCd batteries from emergency lighting fixtures (5 cells, 7 Ah) and I started looking for a way to check if they might still work. While searching for chargers I found model B6AC that charges automatically almost any battery chemistry (various lithium, NiCd, NiMH, lead-acid), can …

NodeMCU networked thermometer

In the last post I made a short introduction on development using the NodeMCU platform with a simple reading of a 1-wire thermometer. This time I will show how to make a basic networked application for the NodeMCU and the server part for a computer to gather some useful data …

First steps with NodeMCU

NodeMCU is a versatile board with the WiFi-enabled ESP8266 system-on-chip, USB to UART bridge, voltage regulator and some auxiliary components. With a price tag of about $9 on Aliexpress it allows you develop your own Internet "things" literally in minutes.

The killer part is a build-in Lua interpreter, so no …