How Italians Got Their Power

May 18, 2024 by Jenny List 28 Comments

We take for granted that electrical power standards are generally unified across countries and territories. Europe for instance has a standard at 230 volts AC, with a wide enough voltage acceptance band to accommodate places still running at 220 or 240 volts. Even the sockets maintain a level of compatibility across territories, with a few notable exceptions.

It was not always this way though, and to illustrate this we have [Sam], who’s provided us with a potted history of mains power in Italy. The complex twists and turns of power delivery in that country reflect the diversity of the power industry in the late 19th and early 20th century as the technology spread across the continent.

Starting with a table showing the impressive range of voltages found across the country from differing power countries, it delves into the taxation of power in Italy which led to two entirely different plug standards, and their 110/220 volt system. Nationalization may have ironed out some of the kinks and unified 220 volts across the country, but the two plugs remain.

Altogether it’s a fascinating read, and one which brings to mind that where this is being written you could still find a few years ago some houses with three sizes of the archaic British round-pin socket. Interested in the diversity of plugs? We have a link for that.

Building An ESP32 Smart Power Strip From Scratch

June 10, 2020 by Tom Nardi 33 Comments

Surely the most straightforward way of creating a smart power strip would be to take an existing model and hack in some relays that you could fire with a WiFi-enabled microcontroller. But where’s the fun in that? Instead of repurposing a commercial power strip for his recent project, [Md Raz] decided to just build the whole thing himself.

The project started with a 3D printed enclosure that could hold the electronics and three panel mount sockets. The use of heat-set inserts makes it a bit more robust for future upgrade work, but otherwise it’s a fairly simple rectangular design. Nobody ever said a power strip had to be pretty, right? In addition to the panel mount sockets, there’s also a AC-DC converter to step mains voltage down to 5 VDC for the ESP32.

In addition to the microcontroller, the custom PCB in the power strip holds a trio of MOSFETs connected to AQH2223 solid state relay (SSR) chips. Once the ESP32 toggles the line attached to each MOSFET, the indicator LED above the outlet goes on and the appropriate SSR is thrown to turn on the power. With a simple web interface running on the microcontroller, all three outlets can be independently controlled from any device with a web browser.

If you’d like to limit your interaction with mains voltages, then we’ve seen some projects that commandeer the low-voltage side of a commercial smart power strip. But remember, putting a Raspberry Pi inside of a power strip might seem suspicious to some folks.

Lethal LED Lantern Leaks Lotsa ‘Leccy

July 19, 2017 by Jenny List 39 Comments

When you take an item with you on a camping trip and it fails, you are not normally in a position to replace it immediately, thus you have the choice of fixing it there and then, or doing without it. When his LED camping lantern failed, [Mark Smith] was in the lucky position of camping at a friend’s compound equipped with all the tools, so of course he set about fixing it. What he found shocked him metaphorically, but anyone who handles it while it is charging can expect the more literal variation.

The lamp was an LED lantern with built-in mains and solar chargers for its Ni-Cd battery pack, and a USB charger circuit that provided a 5 volt output for charging phones and the like. The problem [Mark] discovered was that the mains charger circuit did not have any mains isolation, being a simple capacitive voltage dropper feeding a rectifier. These circuits are very common because they are extremely cheap, and are perfectly safe when concealed within insulated mains-powered products with no external connections. In the case of [Mark]’s lantern though the USB charging socket provided that external connection, and thus access to a potential 120 VAC shock for anyone touching it while charging.

Plainly this lamp doesn’t conform to any of the required safety standards for mains-powered equipment, and we’re guessing that its design might have come about by an existing safe lamp being manufactured with an upgrade in the form of the USB charger. The write-up gives it a full examination, and includes a modification to safely charge it from a wall-wart or similar safe power supply. Definitely one to watch out for!

If you were wondering what the fault was with Mark’s lamp, it was those cheap NiCd batteries failing. He replaced them, but there are plenty of techniques to rejuvenate old NiCds, both backyard, and refined.