Electrical power

The shocking power supplies

Transformerless power supplies are showing up a lot, especially in inexpensive products where the cost of a transformer would add significantly to the BOM. But transformerless power supplies are a double-edged sword. You can get yourself easily electrocuted if you don’t understand them and take proper safety precautions. Poking around in a transformerless-powered device can

Electromechanical thermostat

Here is teardown of Stego FZK 011 thermostat. Thar is an electronechanical thermostat that can control heating resistor and/or cooling fan. The thermostat is based on bimetal strip that bends based on temperature. To get sharp transition and some hysteresis there is also magnet near silver calibration adjustment screw and electrical contacts. Components on board

Car heating on freezing winter

When weather gets freezing cold car windows start to freeze and engine can have problem to start. For this reason in countries where there is freezing cold weather on winter time, people use heaters to help up starting their cars during winter time. In Finland it is common to use engine preheater and interior heater.

European mains power

This post is about European mains power. Electricity in EU countries conforms to the European standard, coming out of the wall socket at 230 volts alternating at 50 cycles per second. While the voltage and frequency are fixed, the mains connectors and wiring practices can vary between different countries in Europe. One thing to note

Mains LED waveform

I saw a quite interesting looking waveform from a 10W LED floodlight powered from 230V AC. It looks like when AC voltage waveform instantaneous voltage lower than some voltage, it takes practucally no current and above it it looks like a constant current load. This is picture of the light. This looks like this uses

Coiled mains cable heating and inductance

What is the problem of using a coiled extension cord? When the power cable passes a considerable load current, it will definitely heat up noticeably. As the load current increases, the temperature of the cable surface will be higher. A cable loaded near it’s rated current can feel that it is warm to the touch,

Origin of Schuko®

“Schuko” is a short form of the German term Schutzkontakt (literally: protective contact),[1] which indicates that plug and socket are equipped with protective-earth contacts (in the form of clips). https://en.m.wikipedia.org/wiki/Schuko It is very commonly used throughout Europe for 230V 50 Hz AC power up to 16A. Origin of Schuko® https://www.plugsocketmuseum.nl/Schuko-origin.html

USB C vs US outlet

Have you noticed that the size of the USB C plug is such that it is possible to insert it to an US outlet. The USB C connector just fits to the wider prong hole in the US connector (slightly too big for thinner prong hole). It is even possible to make the USB connector

CEEFORM Connectors

The CEE form, also known as CEEFORM, is an abbreviation of Certification of Electrotechnical Equipment. Ceeform is a certificate for electrical equipment. It was formerly published by a European body called Commission internationale de réglementation en vue de l’approbation de l’équipement électrique, which is now superseded by IECEE. The “cee” in ceeform socket and ceeform