Mat's DIY electronics

1 year old but not forgotten 2010-04-08 16:30:44 Yes, I know it has been a looong while... I have been so busy with my projects that I did not find the time to document them all on the web. Well, I want to change this and update my blog more frequently.... Starting .... NOW! I will be adding an rss link, enabling comments and adding sections, searches, tags, and a lot more really soon. Before I do all that (or maybe at the same time), I will be adding some posts on the fantastic projects I made/tried during the last year, such as:

A 3-axis CNC machine made of wood. The cnc does wood, metal, plastic and ... pcbs. Engraving, cutting, drilling and more.
Plans of my newest speaker designs.
Some thoughts on the latest linux distribution.
My ongoing efforts to create a g-code exporter for PCB (the linux EDA software).
A couple of simple, yet unique circuits.
Some metal folding attempts.
And a much needed update on my completed gainclone amplifier.

We will have all that and probably more in the incoming weeks. LM3886 or the search for a footprint 2009-05-25 09:37:22 Chip-amps have become more popular recently due to the sudden interest generated in the HI-FI and the audiophile domains by the (now famous) gainclone amplifiers. The concept of the gainclone is pretty simple: you put together a simple power supply to power up a nice big fat op-amp. This design is the perfect easy project for hobbyists looking for week-end projects, since it has a very small parts count. And to top it off, the result is usually quite impressive! There's a lot of kits available from multiple sources, BUT as a true DIYer, where would be the fun in buying a kit when I can do every part of the building process by myself! (And learn a lot at the same time.) With that in mind, I proceeded to purchase my first pair of LM3886 chips. I looked at my local electronics surplus store for a suitable transformer to power them up on the cheap. The transformer is, obviously, the most expensive part in a gainclone project, since the little chips cost less than $10 each. After building the power supply on my breadboard, I had 2 options for the chips.

Bend the pins on the chips to make them fit on my breadboard.
Solder some wires to every pin.

Option 2 was the easy way to go: much simpler and less hurtful for the chips. I was able to test and tweak my circuit and enjoy a nice stereo amplifier very quickly. I even made an enclosure for it... out of wood! I did not have the time to make a printed circuit board, only point-to-point wiring, but it still worked! Nonetheless, I wanted a board for my amplifier. So, I loaded my favorite EDA: PCB (running on Linux, of course!), but realized it did not have a symbol for a TO-220 chip with 11 pins. Therefore, I searched the web for one, but the only thing that came up was a pdf document (found here) explaining how to create footprints for the program.

It's only recently, though, that I took a good look at the document and made my footprint. All the dimensions needed got confusing at one point. I would print my result and find that the pins did not align correctly and that the copper circle for a pin was too small or too big. I did find the right dimensions. (with great help from National Semiconductor's datasheet of the LM3886) I am now, finally, working on board layouts, and you can do so as well with my TO-220-11 footprint! Mat's DIY electronics 2009-05-18 05:46:13 Hi everyone, I have just finished programming this website. I'll post about electronics projects I am doing and those I hope to do really soon. I'm going to start slowly and add more content on a (hopefully) regular basis. Hope you'll all enjoy it! -Mat.