The Calculator is dead, long live the Calculator...

My eyesight problem triggered a new blog motto... I must stay away from the computer when I'm "dedicated" to my home projects (or at least reduce the time to a minimum).
Here it comes "Never again use a Spreadsheet for designing power electronics"! I must admit that for work it is the best thing available,test scenarios, test components, circuit configurations everything numerical at a touch of a "button". But I don't need that, this is supposed to be for fun. I don't need speed of calculus, I want to keep learning the "Art". From now on calculations will be displayed scanned from the squared paper (I still have to find a scanner though)... And these two will have a bit more work...

Thinking back, how many times did I use a graphics calculator for a graphics problem? I don't remember, but not many...
I did love my HP48 in the last two years of university (before that I had a TI 57 II), I had to work for a while to pay for it and my father helped out with 50%.
Once at an exam, the teacher that saw my Texas classified it as "a Grocer's calculator", that was really embarrassing and this was in 1997!(most of my colleagues had either an 48S, the 48SX or the Casio Computer 850??)...
The HP32S was bought recently in Epay, to get something a bit more "portable" and keep "playing" outside...

Pen Life - Rotring Quattro

When these pens came out I could not afford them, they costed about 50EUR (in today's money something like 80EUR) and they looked great... Geeky and Engineer like. As soon as I started working and received my first engineering salary I bought one. Recently I found one (new old stock) in Epay... here are the two, side by side, check the differences...


There's another difference that I didn't even remember... when I bought it the finishing was black matte and kind of "rough" or "sand" paint, with 15 years of use that is all gone.
One not so good side of the pen was that the main writing refill would not last long enough (during meetings I tended to write a lot, not anymore though) and the marker pen was "inconsistent" when you wanted it to write. (here's a product review for a product that does not exist)...

New Crops 2011

Spring is up, time for some new balcony crops! This year, broccoli, turnips and carrots.. They're already sprouting (due to the fantastic weather we've been having in The Hague...
These are my carrots for this year (the clay ball is 1cm diameter).

Just noticed that I need to clean the lens, probably the "little camera devil" touched it...
This is a beetroot that survived the winter.

Hopefully it will grow to "edible" size in these next few months.

SBC6120 - Power Supply Board

It had been planed for ages, but I never had the time or a technical "consideration" delayed me. I finally decided to just do it (after reading the "cult of done" manifesto), the board with the Laser Toner Transfer and HEMA inkjet photopaper, this was probably the biggest board and with the least detail I've ever done (160x120mm).

The board needed only to fix the connectors, the power switch and a switching power supply. I didn't have much space available on the top side, so I went through my "pile of components" and found a couple of single IC switching power supplies (the National LM2575-5V), I also had a SMD version of it (or so I thought) and some SMD Schottky diodes. The board is also used to mechanically fix the 3.5 inch Harddrive.


The schematic was simple, just the switch, the connectors and the switcher, I added a turn on delay to let everything power up slowly (see the LM2575 datasheet).


The power switch (and the lever) are from C&K, but I had to buy an "old lever" as the new levers are much wider than what I could "afford" in terms of space on the front panel (there's no bezel for this older one though).
For the PCB I had some problems, but mostly mechanical. You can only see them when I show the pictures of the completed unit. I had to fit a 10mm inductor in a 10mm space and a 3.5 inch harddrive in 3.5inch (minus 1mm space, there's a screw on the harddrive I had to remove, otherwise the top would not close.

This is probably the only reason why I'll do boards at home, it must be a big board (>160mmx100mm), few tracks and single side, if it misses one of the tests, I'll go for a Fab. board.
After assembly... it didn't work... A quick trouble shooting revealed the cause... poor eyesight.
I had a LM2595S not the original LM2795 with which I drew the schematic and PCB. The pinout is very different. Then I found out I had no LM2975 SMD version. I had to improvise, a through hole package with bent leads and plenty of flux later...


After that mishap, I mounted everything back up and it worked. I formatted the drive and downloaded a disk image and now my SBC6120 boots!



It was done in two weeks! I'll try to keep this "cult of done" thing going on (but some of the tasks need to be broken in more than a couple of weekends).