Category Archives: General Electronics

Video update! Cables and connectors have been installed, I also started some testing.

This video below will show the cabling, the circuits boards, servos and controlling software working. As you will see this is not exactly the finished product, but a test setup to see that everything works as it should. I do not show this too well in this video, but the temperature sensors, motion and a couple other sensors are wired up and working as well.

This was filmed in July, which means the cabin is now a lot closer to being finished. I will upload some newer photos soon. Due to work I have been located in South-Korea for the last 2 months and won’t be going home until end of October – this is why I haven’t been able to work with the project for a while.

I can’t wait to get back home and finish this project and eventually post video/pictures of everything properly installed :-)

Alexander Midteide’s Electronics Blog featured as “Site of the Day” on

As a regulare reader of the site I was flattered to be offered the opportunity to have my blog featured as the “Site of the Day”. It was unexpected to say the least, which is why I took a couple of screenshots to prove that it’s true.

The ClapClap Switch

This is just a weekend project I decided to make just because I wanted to prove how easily it could be done. The idea of course came from Hollywood where all the rich people often seem to have installed clap switches.

As explained in the video, this is accomplished using two opamps, one as a comparator and one to amplify the electret microphone signals. There is also a cap in series and a resistor in parallel to ground in order to detect and hold the peaks. The comparator outputs a nice square wave which makes it heaps easier to process the signals in the microcontroller.

Anyway, if anyone has further question feel free to ask them and I will answer them in the comments field.

CabinControl PCBs has arrived!

Luckily PCBcart had my card made before the lunar new year, and I just got them today! I’m very excited about it, they turned out nicely. People are wondering how the PCBcart quality is, so here are a couple of pictures of the bare boards. I’ll start soldering components as soon as I have time.

Of course I will post pictures when the board is assembled completely.

CabinControl PCBs on their way!

January 17th I sent the gerber files over to for production. They have great specs, and extras like Immersion Gold plating and blue coloured solder mask was pretty cheap. They sent me an email telling me that production may be delayed to until after Chinese new year, which would mean the cards wouldn’t get sent until February 12th… Luckily though, they came through – today I received an email from them telling me that the cards have been shipped!

Packets containing electrical components are coming in from everywhere these days too, it’s great! From Sparkfun, Elfa (Norwegian equivalent of Digikey, only 1% of their articles to 10x the price), Ebay and dealextreme. It’s amazing how cheap components can be when ordering from Hong Kong.

I’ll be sure to post images of the PCBs as they arrive so you can make your own mind up whether PCBCart is worth using for your next project or not. By the way, the board dimensions are 60mm x 85mm (2.35 x 3.3 inches for you empirical people).

Proof of concept video

The C# program is in the very early stage but has enough to display the webcam images and communicate with the microcontroller through USART interface. Even though the microcontroller software is very far from finished too, it still controls the two servos where the webcam is mounted(you can hear them moving in the background as I control them from the computer). The video doesnt show the actual servo/webcam rig, so I added some pictures of that too.

Cabin Control Schematic & PCB Layout

Here are the full schematic as well as the current PCB layout for my CabinControl project. I have not yet sent the boards for manufacturing, so there may still come adjustments. If so I will post them here.

I haven’t really given an in-depth explanation of the system overview nor the schematic simply because I don’t know if anybody would be interested. If I get questions in the comments I will answer them to the best of my ability :-)

EDIT: I added an Eagle3D output version of the board. It’s not exactly flawless in its 3D representation, but nevertheless.


CabinControl System Overview

One of my current projects is what I’ve decided to call CabinControl. This is a circuit that will be installed on a cabin (hence the name) in order to remotely control webcam, cabin temperature etc, as well as observe sensor inputs like temperatures, motion around the cabin, snow depth, daylight brightness and so on. See the figure below for a complete list of interfaces. Currently I am working mostly on the HW side of things, trying to get the PCB design completed and get the board manufactured. I guess I will upload the current PCB design some time soon. When I finish the circuit and board layout I have a lot of coding to do both for the microcontroller (C) as well as for the PC (C#).

Which capacitor to use where?

The electrolytic cap

A lot of people don’t seem to know the difference between a ceramic and tantalum type capacitor. It’s important to learn the pros and cons of all capacitor types in order to choose the right one for that specific application. Instead of going through all the different types myself; here’s a link to a good explanation!