I had obtained three samples of a DDM18SD DIN rail mounted energy meter unit. I got mine from a UK supplier on eBay, but they are available here at AliExpress and in many different places. The unit I obtained was a single phase unit for directly measuring up to 5A and 240V AC, but up … more
I have built an environmental monitoring unit for my workshop. This measures: Air Temperature, Humidity & Pressure PM2.5 and PM10 Particulate values Radiation levels It shows the data on a small OLED screen. There is a large LED RGB display which changes colour if data goes above warning levels. This unit sends data to AdafruitIO via MQTT messages. This … more
I’ve been designing a breakout board for the ACS758 hall-effect current sensor. The first few prototype boards came in and I decided to give them a quick test. The results were not quite as I expected so I thought I’d put write about them here, for others that might be using this IC. These current … more
Following on from my previous post on measuring humidity, I decided to test another couple of humidity sensors I had lying around. These were the DHT11 and the DYPTH01B. These are both low-cost capacitive sensors and both had been obtained when I put in an order with a Chinese supply website (Sun Tek Store). Neither … more
For a new project I am looking at measuring weather data in remote locations. This is for a low-cost, low-power wind data logging unit. The main parameter to record is, of course, the wind speed and I am doing this with ten minute averages from a pulse-output anemometer. While this data is useful, it would … more
Accurately monitoring lead-acid battery state-of-charge would help with the long-term sustainability of off-grid renewable energy systems. There are a number of ready-built products already available, mainly for the recreational vehicle market (eg. boats) and are relatively high cost (too high to include within a small off-grid power supply system). There are also a number of … more
I’ve been trying to accurately measure voltage for my open-source charge controller project. This project relies upon accurate measurement of voltage as this is used to control the regulator. I have been having some difficulty getting reliable and accurate voltage measurement, so I wanted to figure out why that was. I am using a simple … more
A number of the projects we are involved with require accurate monitoring of DC currents. Here we explain the numerous techniques for measuring DC current flowing in a line, highlight some of the multitude of integrated circuits available and list the pros and cons of various techniques. This is an on-going work – please post … more
For a recent project I was asked to measure the current from a solar photovoltaic (PV) system. This is a typical request as knowing the current is useful for control systems and for measuring power and energy. This blog post highlights some issues and ideas for measuring current. … more
While working on a wind/PV system in a remote area of the Philippines the need for a voltmeter which showed the system (battery) voltage in detail arose. Only analogue V and A meters were available in the local town. This simple design explains in detail how to convert a low range ammeter into a voltmeter … more