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Visar inlägg från 2015

Guide: Get more distortion from an HCM65R amp

I got my hands on an HCM65R guitar amplifier. It's an okay amp I guess, if anything it's loud enough to rise a mob against you even if you live off in a rural area. But, something that's been bothering me and many fellow reviewers it is that it lacks distortion. For me it's usually enough for blues but some palm muted metal, like Into the void with Black Sabbath, comes out a bit soft.

As both of the volumeknobs were broken I took the amplifier apart and started thinking about a way how to get this loudly purring kitty to growl like a beast. When taking it apart I saw that the PCB is really old school with large components placed with a lot of space between them. So, hack friendly! I found out what to change and how, tried and it worked. Check the video below to hear how different it got.

Demonstration I play some random stuff with and without the modification and I think that the difference in tone is very clear.

How to do it This is for you who knows how to solder and…

Visiting Itaipu

Itaipu dam has the second largest rated capacity of all hydropower plants in the world, next after Three Gorges Dam in China. However, as the Paraná river has a more even flow throughout the year, the Itaipu dam in the end is the hydropower plant in the world that supplies the most energy.
A normal year, this plant alone supplies more than 150% of the nuclear plants in Sweden together.

The dam was built and is operated within a binational co-operation between Paraguay and Brazil, that then divide the energy in between them, The ground where it stands has a somewhat international status.

Traveling in Brazil, I off course had to see this dam with my own eyes. Let's see some pictures I took. 
I photographed this overview picture of the dam for a start. 
The dam seen from the side. It doesn't look to vast here, but it's 7235 meters long in total. The turbines outlets are underneath the water surface and cannot be seen here.
 This is the outlet of cooling water from the generato…

What "extremely hot" means in Sweden

Last summer in Sweden 2014 we had like five days straight with temperatures around 28 celsius (82 fahrenheit) during the day. Such temperature is considered more or less extreme and during such circumstances things go bad for some of us frozen swedes. Yeah, you read correctly, that is extreme for many of us. You're laughing right? Come here when it's -5 celsius instead and see who has the last laugh ;) Alright, I'm exaggerating a little. bit Most people like temperatures as such. But I believe I found an exception here.

Most housings in Sweden don't feature a cooling system, which is reasonable. I mean, it would be sort of the same thing as opening a sand shop in the desert of Sahara. However, sometimes maybe there is a need for sand even in Sahara. Some fellow engineering student (I guess), suffering in his rented student housing in Gothenburg, found a remedy to his hardships. Down at the yard there was a storage room for solid waste were disposed fridges ocassionally…

Improvement of Skype

Being abroad I'm using Skype regularly. During calls with some people, the call starts just fine but is drenched in low frequent noise after a while.

From some instrumental recordings I've done using my laptops internal mic, I knew that it has quiet a lot of background noise. What if that noise is transferred to the other persons speaker, amplified, fed back into my speaker, fed back into my mic again and added to the background noise it produces already, back to the other persons speaker and back again creating an unstable positive feed-back loop?

The theory was easily proved in practice. By using head phones, the feedback loop was broken and the high levels of noise disappeared.

The software engineers at Skype could probably have good use of the noble teachings of Nyquist to get rid of this. I bet though that a simple noise gate could do the trick. There is one such avaliable online as a plugin but Skype hasn't incorporated that in to their software yet as standard.

[VAWT] Affordable wind measurements

The shop Clas Ohlsson in Sweden sells a spare anemometer for the  WH-1080 weather station for a hobbyist friendly price around 15 euros. This anemometer can probably be found in other countries too.

The WH-1080 spare anemometer

Here  you can read about how to use this anemometer together with an Arduino or any other embedded system.  As we couldn't find any data on the characteristics of this sensor, we did our own calibration in a wind tunnel and the results are presented in the report above. This anemometer was used in a Bachelors Thesis project related to the devlopment of optimization of the Savonius Turbine, here tagged [VAWT].

[VAWT] A DIY method for determining the BLDC machine constant

Not all manufacturers publish data of the machine constant for BLDC machines, relating the produces torque to current through the machine. This constant is usually called machine constant too. In the wind turbine project we used a hub-BLDC machine intended as a hub-motor for bicycles as a generator. Neither the manufacturer nor the supplier could provide this machine constant. We didn't have access too a dynamometer for testing it neither. Furthermore, the hub BLDC wouldn't likely fit into most dynamometers anyway.
Method overview 

Therefore I developed a method to determine this constant that is fairly economical and doesn't require much specialized equipment. I started to dig deeper and deeper into the grounds of knowledge, and the what started mostly as extensive self note became something more like a non-revised report.
Read the Step-by-step instruction summary hereRead the full report here Any comments or feedback regarding the report content is appreciated. Here is a c…

[VAWT] Awarded!

So I wrote applications for a competition for bachelors thesises at Chalmers University of Technology, called Bachelors Challenge.  After passing two steps of selection, we got to present our concept in front of a public audience and a jury consisting of representants from Chalmers and various companies, including the internationally famous Ångpanneföreningen. We competed in the category "Green Initiative and Sustainable Development".

Madeleine, another person from our six person team and I held the presentation. Competition was hard. One of the competitors for instance presented a concept for converting plant matter that is wasted today into useful plastics.

To our help Jens and Madeleine, from our  group consisting of six persons, built a model of the windturbine. As we couldn't find a suitable source of wind we decided to spin the turbine with a DC motor instead. Then we used my previously designed software to make an onscreen live demonstration of the performance, w…