old CO2 laser to cut … meat

We were recycling some medical equipment in 2008. And I found broken CO2 laser tube. So here is abridged translation of old article about laser tubes. BTW, after several years I bough hobby level CO2 laser for plastic and wood cutting. But it is another story…

It was “open core” or stream laser, with missing gas preparation system. The only use for it was to open and look inside for details. Output of the laser was 70W, meanwhile power suply for it was … 5kW. Not very efficient.
CO2 laser to cut meat of the humans

Here is some warning stickers/decals:
waning laser radiation
It quite powerfull laser, so warning is about scattered radiation. Even partial reflection can damage you eyes or burn your skin. (I managed to put my hand in unfocused 40W laser beam for short pulse and it hurts!)

All laser element were damaged by watter. But some components maybe are usable:
laser mirror zinc selenide
It looks like zinc selenide mirror. Or maybe semi-mirror. Or maybe it is just window to pass infrared waves from laser body to external mirror system. ZnSe is insoluble in water, so the finishing of the optics is quite good. But all gold plated mirrors were damaged.

Here is mechanical device with mirror/window installed:
laser mirror holder with micrometric screws
This is piece of mechanical wonder- it is sealed, but adjustable with micrometric screws.

The end of laser tube:
open laser tube holder
It is visible connections for watter cooling, gas flow (It is open tube, flow laser) fitting and high voltage connection.

Laser tube was damaged and cracked. And without gas preparation system, flow laser are useless.

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Repairing Nokia N80

Yeap, it was cool to have Nokia N8 in 2008. And it was cool to repair it… Original post from spring 2008:

This is consequences of certified repair of Nokia N80. Old metal case was damaged and was replaced. First of all it was not original part. Second- phones lost image on LCD screen. The other phone was bought and this one was left in the drawer. After some time “they” forced me to repair the phone.

Nokia N80 ribbbon cable LCD problems
It looks like, that certified technician crushed original flat cable with case and after some time it broke.

Nokia LCD cable broken repair N80 selfmade phone
Red arrow show the damage. I bought new ribbon cable in eBay and replaced. It was very strange, that parcel came from USA, not China.

Big thanks for Mr. Rolf2 for being very lazy to repair this phone and sending me the link in youtube with instructions about this phone disassemble.

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Dekatron

Wiki:

Dekatron (or Decatron, or generically three-phase gas counting tube or glow-transfer counting tube or cold cathode tube) is a gas-filled decade counting tube. Dekatrons were used in computers, calculators and other counting-related products during the 1950s and 1960s. “Dekatron,” now a generic trademark, was the brand name used by the British Ericsson Telephones Limited (ETL), of Beeston, Nottingham (not to be confused with the Swedish TelefonAB Ericsson of Stockholm).

I have several old soviet tubes A106. It is high speed, hydrogen filled dekatron. It is special tube to count or divide impulses. This particular tube is “very soviet”- it is unstable, sometimes misses pulses or jump two segments from one pulse. Maybe this happened because of very simplified circuit I’ve used to test?

Dekatron tube in action
It glowing everywhere because of long exposure when making photo. It was fed by 50Hz mains current and tiny dot run around 5 times in a second. And the color of the tube is absolutely different.

Here is the animation:

And here is the circuit diagram to test the tube. Warning! High voltage abroad. Schematics are very typical- voltage multiplier and pulse shaper. The only problem with hydrogen filled tubes is high working voltage.
dekatron schematics

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Color LCD screens

This is another “filler” article from old blog posts. When I don’t have any fresh and interesting ideas, I just write short filler articles to show regular blog reader that I am still allive. For this English translation blog these articles are useless, but I need to translate everything as sometimes you can catch the system how my ideas are born.

Original article dated 11th of April, 2008.

trash mp4 player as source for components
All these player have same problem- dead lithium battery. Maybe not dead, but over discharged. Just recharge battery with external charger and you’ll have another useless gadget. I was using these devices as source for small lithium batteries, other small electronic components. It is pitty, but LCD screens are without any documentation and I throw them away.

I found 1G or 2G flash chips from Samsung inside, FM radio modules, small charging circuits and TD018THEJ6 LCD screens. Screen resolutions is very bad and now there is better alternatives.

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Infrared thermometer

Ometimes I need to desolder big chips from PCB- like motherboards controllers, GPUs and other “heavy equipment”. For this purpose I used big hot air gun without any thermocontrol. To check the temperature of the chip I need something simple. And this simple and cheap device was IR thermometer from some China seller.

Infrared thermometer
It is not accurate device- as all this type instruments, it give “aproximate” result for viewing area, so to check spot temperature you need to place detector as near as possible.

For testing and calibrating I measured temperature in my fridge- minus 16°C. Boiling water in the kettle is 99°C :) , inside my mouth 36° (if you are ill, it will show a bit more than regular thermometer. You must measure temperature inside human body, outside temperature is wrong).

Temperature reading are not very precise, especialy if you measure something glossy. I think that target must look more like “dark body” to prevent from reflections and wrong readings.

Temperature ranges for this cheap device are from minus 32° to +320°C.

There is useless laser to find target.

This article was written on 10th of April, 2008.

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Site status for 2015.03.11

I decided to “fast translate” my Lithuanian blog articles to English language. There is no special English posts here. This is done for English language readers- my Lithuanian language blog is almoust untranslatable by google translate- it is written in technical language and lots of slang words.

All articles are abridged. Also, there lots of interesting stuff in original comments section of Lithuanian version.

Sorry for grammar errors in English version. All translation is done “on the fly” without checking for grammar and spelling. Spelling error will lower google ratings, but this blog is not for google, but for people searching for information and ideas.

BTW, today is my coutry’s birthday! 25 years as we are from Russia… for second time. First time we run from them in 1918… I don’t want to get it for third time.

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Mess-up with Kynar wires

This is translation of old blog post from april 2008.

I am very happy, that exist such thing as Kynar wires… I used some other PCB for foreign software and messed up some port names in AVR ATMEGA controller. So I cut the traces and put Kynar wirewrap wires.

ATMEGA AVR capacitor measure with some kynar wires

Also, I forget to place ISP connector in my PCB design. Where I was looking?! But at least it works and it is quite good capacitor meter project. I works better with big capacitors compared to old LC meter (lithuanian blog link).

This project is “borrowed” from site pontoppidan.info/lars/index.php.

Circuit diagram:
capmeter AVR circuit schematics

Source code: AVR capmeter source code.

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Acer n35 GPS

This is abridged translation of old Lithuanian web blog article date from 2008.

I’ve sold several 5AR4 vacuum radio tubes in auction and received several virtual bucks. This was very small ammount of money, so I decided to buy somethis for fun. It was Acer n35 handheld computer, sold “as is”. As far I know, it is dead battery :)
So I payed about three vacuum tubes for this device:
ACER GPS n35

At first this device was completely dead. But this happens, when you depleat liion battery- it locs and do not accept charge unless you give it “kick start” with external power supply.
So I dissasembled this handheld device and removed battery. Using external power supply I kickstarted cell to charging mode and finished charging using selfmade Liion charger.

Handheld computer is very weak and primitive… and using windows operating system. I found several software sources and installed navigation software.

As far for 2015: this device was used for some navigation and games. After some years it was abandonend and still sits in the drawer. BTW, the battery is the same and never locks again. Just connect external USB cable and after few minutes device boots up.

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Logic analyser

Original post from 2008, now there are good alternatives to this experiment.

There is one very usefull and practical instrument for hobbyist- logic analyser. This is just instrument to collect variuos multichannel data to computer ant then analyse it offline.
Some analysers were connected to computer LPT port, others are more sophisticated.
Some of electronic events are very fast and to catch them we need to quantize data very fast. FPGA based systems are the only cheap way to do it, especially if you have spare FPGA board.

I found in the internet some third party firmware and software for Altera DE2 board. And now sampling frequence is 100MHz. All data is transfered from FPGA board to “big” computer via serial cable (using selfmade USB serial cable. BTW this selfmade cable is much more reliable than many Chinese made cables).

FPGA logic analyser
It is DE1 FPGA board with Cyclone EP1C20F400C7 chip. I connected to other device using 80 lines IDE cable. (every second line of the cable is grounded).

I’ve tested this design with ZicPlay media player screen. (as for 2015 I never used this screen and all players moved to trash) I just wanted to peek to data to find what data is screen bus.

FPGA logic analyser

It is Zicplay device boot moment snapshot.

More information and all software/firmware are in Lithuanian blog page.

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High power white LED and Liion battery from laptop

This is old post. Original post dated 2008.03. You can visit it at original page in Lithuanian blog. Also try to read comments to this blog post.

The old post is about LED light torch using lots of typical small LEDs to create light. But there are better LED diodes- high power ones. One of these diodes I bought in local shop. But seller could not tell me exact properties of the device- typical for our shops and for noname China products. The only thing I know about this device, that max current of the diode is 700mA (some other sources state something about 800mA).
Diode is mouted on a small heatsink, but this is only to spread heat to big real heatsink.
As it was quite expensive diode, I decided to use real LED driver chip for it. I decided to use TexasInstruments TPS61058/TPS61059 (SYNCHRONOUS BOOST CONVERTER WITH DOWN MODE HIGH POWER WHITE LED DRIVER). This chip, as stated in datasheet is usable with Liion battery and has all protections buil in.
Chip is very small, there is blog article in my web pages. Original Lithuaniain one and there is breef translation to English version.
Finished device looks like this:
Smart White LED torch

After power up everything works very fine, but heat sink is too small. I am using only 570mA current (and the voltage drop on the diode is 3.37V. So it give us only 2W of power).

Smart White LED torch

There was some problems in the design of this PCB. I did not managed to get higher current. There is quite complicated working current and voltage setting system using 5 resistors! I’ve set 0.7A current, but even using fancy startup schematics it didn’t start in full power. Maybe I used bad L component- it is critical.

Also, I’ve mae experiments with TPS61059 and it looks like that this chip is 0.5A max current… :)

Finished device is quite small and compact. As I used single side home made PCB it is a bit bigger. If I used double sided, everthing could be much better. (Check Lithuanian version and more recent articles- I am using professionally mande double side PCB and many of mu projects are rebuild using “real” PCBs)

Biggest devices are electrolitic capacitors (3x22uF) and inductor. Inductor is only 4.7uH but it must handle quite big currents. So it is not very small. I used thantalum and maybe alluminum polymer capacitors, few ceramic chips. Almoust all components are recycled.

LED is quite bright, but the light is not focused. The best way to get good torchlight is to used some optics to focus light to single spot.

Such focused light is way much better than older constructions.

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