Few words about me:From very childhood I loved computers, electronics, lasers, sulfuric acid and liquid nitrogen. I always wanted to be making microchips, UAVs and see nuclear explosion.
Now I am doing software engineering and in the spare time - some microelectronics and physics/chemistry experiments.
I live and work in Russia, Moscow.
Flickering LED reverse-engineering (+RGB)1.5 years ago there was an attempt to reverse engineer behavior of flickering LED as a black box. That time the results were that flickering does not repeat itself (so it's not something like LFSR pseudorandom generator), brightness is set by PWM and there is some distribution of brightness. Since then more results wereachieved, and I also got some time to dig in.
Previously it was discovered that there are multiple variants of die of flickering LEDs. You may see photos and read some clues on their inner workings here - siliconpr0n.org, cpldcpu.wordpress.com, hackaday.com. It is surprising that seemingly simple task of flickering LED is being solved numerous times by full custom ASIC, and there is even some competition/progress!
DIN modules and busbar solderingBefore: DIN circuit breakers were connected in soviet-electrician-style "it did the best with the stuff I had", consecutive using usual wire. Effectively all current goes through point contacts on first module. These places are the main reliability and safety concern - it could easily overheat and cause a fire. For example on the right see similar setup under 4.25kW power consumption (20А) via thermal imaging camera.
Amateur astronomy starts now!For quite some time I wanted to buy a telescope - but it was nowhere to store it in rented apartment. Here is my previous attempt. Finally this time has come - I ordered Sky-Watcher 10" DOB SynScan from famous German shop http://telescope-express.com. Even with delivery and customs taxes it was cheaper than in local stores. 10" was selected as largest diameter which could still be used at balcony.
Switzerland 2014In the summer of 2014 i've been on business trip to Switzerland. Finally got some time to share few photos.
The most iconic one is probably the cows eating grass in Alps, 2000 meters above the sea level:
Requiem for a winter 2015
Solar eclipse 2015Today there was 65% solar eclipse in Moscow. Probably the last time I am taking astronomy photos with Sony 500mm/F8 - my new telescope is already at the post office
AMOLED shenanigans and new microscope lens Olympus LUCPlanFl 20x/0.45Finally managed to break smart phone glass for the first time. FIrst 4 times it was hitting concrete just fine, and now it landed straight face-down: screen was shattered. Bought glass replacement kit on ebay including UV-curing glue. Old glue+glass is removed by heating to ~120-150 °C.
Unfortunately I managed to overheat 1 spot to 220 °C which lead to unexpected effect: black (organic?) contrast-boosting pigment has burned and revealed display internals in more details. Also, the most sensitive, blue subpixels stopped working in this spot. With my "new" (ebay again) microscope lens LUCPlanFl 20x/0.45 with cover glass thickness correction I managed to make photo of AMOLED internals with more details (for comparison see earlier photos):
PCB cross sectionEver seen PCB cross section? Total thickness is ~1.5mm, you can even see how glass fibers are interleaved.
Temperature stability of AirSpy SDR receiverRecently I got AirSpy SDR-receiver : it has 20Mhz/12bit ADC comparing to 2.4Mhz/8-bit one in RTL2832-based devices. Capture bandwidth is 9Mhz. Also, it uses TCXO with 1.5ppm frequency error spec. In this article I focus on it's frequency error vs temperature. More detailed review of AirSpy will follow in the nearest days...
BTW, for the first time in human history we have blueberry-cooled electronics:
Here are frequency errors. I was measuring 35-th harmonic of FE-5680A rubidium frequency standard generating 2^23 Hz, i.e. ideal frequency should have been 8192*1024*35=293'601'280 Hz.
|Hardware||Quartz (E4000+RTL2832)||AirSpy TCXO|
|After warm-up||293'627'555 Hz +89.49ppm||293'601'318 Hz +0.129ppm|
|Tcase ~0C||293'626'824 Hz +87.00ppm||293'601'185 Hz -0.324ppm|
|Tcase ~60С||293'628'227 Hz +91.78ppm||293'601'386 Hz +0.361ppm|