Savel brain dump in English!

I would like to introduce part of my workbench. It is computer side of my workbench. There is electronics workbench, but it is not described here. I’ve made some order here before making pictures- regularly there is a big mess here:

Small description of the stuff:

1. Very old, >20″ SGI (Silicon graphics) monitor. It is time to throw it away, but from time to time I need to connect so old unix box of some PC with nonstandard video timing. This monitor is capable to sync to very wide range of sync signals (or even without them- sync on green). The only problem is rare 3W10 connector. I’ve made some cables for it. Very heavy.
2. Some old unix boxes: SGI Indy, Sun Sparc Xterminal 1 and Sparcstation 5 (from recent blog entries you may understand were I found last one). And what is displayed on CRT screen.
3. My regular computer, every day it is getting older and weaker compared to new ones. It is P4, 3GHz, HT computer. (nor D, nor Duo). with some SATA drives and 2GB of RAM. I was sick of out-of-RAM messages and virtual memory performance. Now memory is cheap and I recommend to invest some money to RAM.
5. Two 14″ LCD monitors. I love Lot’s of desktop space.
6. some HDD.
7. Black keyboard. I love classic small keyboard. I hate “natural” keyboard and keyboard with “media keys”.
8. Classic Russian tea cup. Regularly I drink white coffee with lots of sugar.
9. Sun keyboard. It is only connected to test sparcstation.

And now backstage…
Continue reading →

From computer tomograph PSU, I removed battery of capacitors. It is 12 high power electrolytic capacitors. 6 x 12000μF and 6 x 8200μF. All caps working ant 400V (450V surge). Total 121200μF (0,12F). We can charge them to about 400V and store about 9696J of energy. Lots of energy. And lots of lethal energy. It can kill you.

More about capacitor calculations in older blog entry.

I achieved personal top record in braking electronics. Today (Nov 14th) I disassembled computer tomograph. As whole device was too big to fit in the van, I don’t have classic photos of the doughnut (donut). I have only partly disassembled device images.

Here is the images of “super computer” displaying human body slices:

In fact, it is very old, Sun Sparcstation 5 computer, with 256Mb RAM, some external CDROM and hard-disk. With SunOS and Philips software.

Here is the remains of donut. The device was ancient. It was made in 1995, but the design is much older. Main custom computer is made using DIP chips in 5V technology. The only identified CPU was MC68020 working at 16MHz, and several custom made or maybe MIPS CPU’s on several printed circuit boards.

It was X-ray tomograph. Images are produced using rotating x-ray tubes and 192 detectors. This whole bunch of heavy metal is rotating around human body. This system is powered from 380V 3 phase mains system. The power is converted to higher frequency, so all x-ray high voltage transformers are much smaller. But main PSU is very big, full of big capacitors and power IGBT transistors. Lots of power is used for such device- mains braker is 250A.

As device is very old, only few interesting components were found inside. It was great disappointment.

Some time ago, I tore a piece of cinema film from local cinema theatre. The movie was some dark work, about vampires or something. Recently, in wikipedia I found article about Dolby digital encoding on the film tape.

I found my film strip and checked it for digital data. Under microscope I found dolby digital data encoded in matrix bar-code between perforation. Also, I found three additional low rate digital data tracks. There is no data what is encoded here. In wikipedia example there must be analog channels…

I made the photo using small microscope with 25x magnification. Width between two graduations with numbers are one millimeter. You can see Dolby Digital logo in the center of dot matrix . Last image is borrowed from wikipedia:

HDTV, hdtv… whattheheck is that HDTV? Here is some screenshots to describe the size of unscaled HTDV image. You don’t need to know about pixels and lines, do not need to describe difference between 720p and 1080i… Just look to the image and find little windows start menu gadgets on the bottom of the image.

And some unscaled piece…

Oh, it is great treasure. I’ve made sweep generator, but I didn’t build any attenuation device for it. I’ve tested regular carbon variable resistor, but the output was too noisy. I’ve also tested high resistance wire wound variable resistor, but the inductance was too high and the attenuation in higher frequency was horrible.
By a chance I found very old (~1964) sweep generator made by some USA company. It was full tube design and not working and partially disassembled. But I was in luck and original attenuator was intact. Also, the device as build in stand alone version- two solid metal cans with BNC connectors. The only problem was t find some inch-based, American tools to unscrew all nuts. I live in normal world where metric system is used.

These two metal cans are stepped variable resistors. But they are calibrated and designed to work in wide frequency range. One attenuator is for tens of decibels and other for apiece (ones). Smaller one has 0, 10, 20, 30, 40 and 50 dB attenuation and bigger one is in full scale from 0 to 10 dB and one very useful position- open circuit.
The device is very solid, very well build and working without any glitch. And device is about 43 years old!