Just short demonstration of gyroscopic effects in high speed hard disks. I had some useless hard disks. It is old SCSI server disk ST39102LW. It is only 9Gb, but 10000 rpm (10K). This increase effect to noticible level. To feel effect you need just try to move working disk. I am not going to explain forces in this disk, lets give some words to wiki:
A gyroscope (from Greek γῦρος gûros, “circle” and σκοπέω skopéō, “to look”) is a spinning wheel or disc in which the axis of rotation is free to assume any orientation. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the conservation of angular momentum.
And look to this short movie in youtube:
Do not do this trick with good disk. And not effects with SSD ones
Yes, it was satellite transceiver. For receiving and sending information to satellite.
Sometime I post messages about items I dissasemble. This was quite a big device:
It is not compressor, it is satellite transceiver from Hughes Network System. Such device were mounted on big satellite dishes. There two “heads” here- on for receiving, another one- transmitter. Continue reading →
I had very short time to remove some Atmel (AT90SL2343T) chips from discarder NOKIA communication equipment boards using standard hot air gun. It was very high quality PCB boards so I made some experiments about self positioning of some SMD elements to solder pads. Main idea is, that good design board can help solder some bigger elements. In this video big transistor-like element (National semiconductors LM2937) moves to its landing place.
From young years I was interested in showwave (HAM) radio, but due to economical and political situation I never started (you know, the axis of evil- soviet union and etc.) Later I managed to listen some of the HAM radio stations using old JVC radio when I was out of the city. The radio itself is not designed to listen SSB or CW signals, but sometimes I can understand some of the voice talks. Especially Russian HAM users- they sometime are using all AM/FM moduliations and curses every second word.
But I never managed to understand CW (morse code)…
Now, when there are lots of software, there is no need to learn that code. Just dowload software, start it and connect to your radio. Continue reading →
It is some PCB from Adaptive Micro Systems LLC, USA. This comapny specializes in LED advert production. From simple single color static board to full RGB color outdoor monitor.
Mine LED board is 72 x 24 RBG LEDs. With dinamic connection and some FPGA control. The protocol of the matrix itself was unknow, so I reverse engineered all the connections between chips and programmed my own FPGA code.
As it is FPGA on board, all reverse engineering was quite interesting and “solder free”. I just connected newly populated programming connector with my byteblaster and started software…
And after some time…
After all FPGA pins were traced, the only thing was created whole dinamic display with normal video data.
Here is some random data from clock counters.
It was very interesting: Red and Green LED are powered from 3V source, meanwhile Blue LEDs are powered from 5V source, also all logic chips are powered from 5V (FPGA has it’s own regulator on board).
This is very logical- blue LEDs have higher threshold voltage, RED can work at much lower voltages. So, to keep board cool (regular linear regulators on board), multivoltage PSU is used.
Check original post in Lithuanian language. There is interesting information in comments section.
If you have some questions, take a note, that this post was originally posted in 2008.
This is starting post about very interesting project. Try to guess what it is?
This PCB is populated with serious stuff. Big square chip is Altera Cyclone EP1C6T144C8, 30 pcs of MBI5026CD, 8 pcs of HT04 (standard chips), 24 Fairchild power mosfets, 3 linear voltage regulators, one 18.432MHz oscilator, UTP connector with 4 LVDS lanes from FPGA. Byte blaster connector for FPGA programming and FPGA bitstream ROM. On other side there are 1728 components with total 5184 discrete active components.
I bought this item in ebay for $130. And it was very expensive for me.
When this post was posted, it was 2008 May. The exchange rate for USD was quite low compared to our local currency. Today (2015) we do not have local currency- we joined eurozone. And exchange rate for USD is quite high.
For my laser experiment I am using collimators from old laser printers and copie machines. Especially from copiers.
A collimator is a device that narrows a beam of particles or waves. To “narrow” can mean either to cause the directions of motion to become more aligned in a specific direction (i.e., make collimated light or parallel rays), or to cause the spatial cross section of the beam to become smaller (beam limiting device). (source- wiki)
These devices are adjusted for copying process and IR laser. Meanwhile I need to use other settings. It is quite difficult to do this, as everything is very stiff and glued with some warnish.
First of all, remove all the parts if it is possible. Especially all plastic parts. Continue reading →
The first version of harware had serious problem- big geometrical distortion. So I added additional mirrors to lift laser beam. Also, I moved voice coils as near each other as I can. The finished scanner is much more smaller:
I placed all optics as precise as I can- only 45 angles are allowed (this precise alligment was done using eyeballing only ). The result is much better, but still there is some other problems. Also, the voice coild have it own resonant frequency and in particular situations, the amplitude of the mirror angle is much higher. The main problem is my audio amplifier and Amiga computer emulation. I need low frequency amplifier working from DC to high pitch sound.
BTW, all laser mirror are “metal to front” type. They are salvaged from old copiers and laser printers. Regular mirrors have “glass in front” structure, so laser reflects not only from mirror side, but from the surface of the glass. Also, there is reflection in inner glass mass- the beam is reflected many times and lots of light power is lost.
For more information, google for “free space optics“.