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Curiosities: Inside a 1970s professional multimeter

2018-08-12 17:32:44,  In: Electronics, Curiosities

Mera V640 is a multimeter made by Polish Meratronik plant in 1970s. It is an analog meter, able to measure voltages (1.5mV - 1500V), currents (0.15uA - 1.5A) and resistance. With specialized probes it was possible to measure high frequencies and even temperature. In 1970s Poland started to make international deals, usually with licenses. Some licenses were bought, like from British ICL for their computer designs, German (western) Grundig (tape players), or Japanese Busicom for calculators, but Poland also manufactured their equipment for export. In 1972 the Masteranger 639 multimeter has been made for Conway, a Canadian electronics company, and manufactured purely for export. The design was successful enough that it was also manufactured for British Marconi company as TF 2650. Year later it was also sold in Poland, under V640 name, after some changes in range switch and adding temperature probe.
These times, export and import with eastern block country was very different than typical transaction,...

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Expanding Arduino UNO memory with 32kB static RAM chip

2018-07-04 17:42:04,  In: DIY, Electronics

Arduino Uno is a cheap microcontroller platform which can be used in lots of applications. If we prototype our solution using Arduino board, it is possible to dump the Arduino board and use single microcontroller instead which is even cheaper and looks more professional even on an universal solder-in PCB. However, ATMega328 chip used in Uno has a significant drawback - its memory which is only 2kB. If we want to make a small control device it's not a problem, but for some specific applications 2kB may be too small.
For example, since few weeks I have an idea to develop a BASIC computer using AVR chips. Implementation of Tiny BASIC uses some memory and has some code clutter which can be replaced with something more usable by the cost of e.g. moving storage code to external devices. Unfortunately Tiny BASIC leaves a very small memory for user's program and its variables.

So what are options to add RAM into Arduino?
- Use a larger Arduino module. This solution is present in Internet forums all...

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Debian Linux on a GPD Win

2018-01-05 22:09:17,  In: Linux, Debian

OK, so I bought a GPD Win. Small, Intel-powered computer with 4GB of RAM, Atom processor (2-core, 4-thread?) and 64GB of SSD. Unfortunately, with Windows 10 by default.
Because I found Windows 10 unbearable even when following the manuals to optimize and make it smaller, I decided to try with Debian.
Unfortunately this device is a completely closed UEFI machine so it doesn't allow much modification. However, I found Debian USB sticks, when not touched, bootable.
This is a set of notes which are based on Hans De Goede's blog entry about installing Fedora on GPD Win.

   What will be needed

Installation of Linux on GPD Win is quite specific and different than typical Debian installation. Many drivers for things like Wi-fi or sound chip are absent, improperly installed or misconfigured so it's needed to patch the system up. To do it, you need
- A GPD Win
- A 4GB USB stick or bigger
- USB hub. The faster the better.
- USB wi-fi adapter...

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About PC power supply units

2017-11-21 10:26:00,  In: Electronics, Curiosities, Other

Recently I acquired a few power supply units for PCs and I decided to share some knowledge about their quality. Because these units were defective I had to open them, fix if possible, and re-solder wires as they were from some e-junk wjere copper is valuable. Testing was simple: Load the power supply unit with an old, damaged IDE hard disk, turn it on, check voltages (they should not be well OK, as one old hard disk is not enough to keep regulated line), then load the unit on 5V line with 12V/21W light bulb and check regulation then. Most passed these tests after capacitor repairs.

   Tagan TG380-U01

Let's see the first example: The Tagan TG380-U01. Tagan is known as manufacturer of a good, high-end power supply units, and it looks like they made them really well. The unit is packed with technology, they put large heatsinks and thermal regulator on a separate, small board. Because packing is tight, two fans are pumping air through the unit.

Here is an example how the good power supply unit...

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Re-making a gear for tape memory

2017-09-24 01:47:52,  In: DIY, Electronics

A long time ago I acquired a microcomputer-grade tape recorder produced by Polish factory: MK-450. The problem with this device and a few other tape drives (like Mera one for large cassettes) and even consumer-grade decks (MK-250) was a poor quality of its gears prone to breakage. Usually, during seeking or playback, a loud crack is heard and tape is pulled into recorder or forward seeking stops working while motor is still heard. Recently I got a possibility to print something with 3D printer, so I decided to experiment with it. In this post I'll show how to re-produce the existing, physical gear into computer model. To quickly show things, the result is nice:

   But... why does it fail?

The plastic used to make these two specific gears (in MK450) is different than polymer used in other gears. It degrades into white, crumbling powder with atmospheric contact and probably...

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Installing adNauseam on PaleMoon and the new malware problem

2017-09-02 13:30:12,  In: Hack, Other

Recently PaleMoon developer decided to blacklist adNauseam extension, so here is a quick method of re-enabling it:
1. Go to about:config
2. Set extensions.blocklist.level to 3.
3. Install addon, go to Tools -> Extensions and turn it on there. Remember that it takes the function of adblocker so will collide with most Adblocks.
4. Watch your addons as this may allow to install uncertain ones in the future (currently only adNauseam has this level). If you want to know, the list is online-updated and is maintained in blocklist.xml in your profile directory. Configuring adNauseam, if your workflow involves visiting only a set of trusted sites you should turn on exception for non-tracking ads.
And small explanation what is it.
The add-on fights with unfair malware-delivering companies (today re-defined as "advertisement") by hitting their collaborators - website authors. Then, according to ideology called "free market", authors should change malware...

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Curiosities: Inside a lab-grade power supply from 1970s

2017-08-22 01:17:11,  In: Electronics, Curiosities

Some time ago I was looking for an used adjustable power supply unit. Finally I had a possibility to purchase a 300W adjustable (0.1-30V, 10A max) power supply unit for a relatively lower price. The only thing about it was that it was a unit from early 1970s, transformer-based, 25kg of hardware. I finally got it, brought home and decided to restore it.

It is a ZTR-1/71 power suply unit made by Inco in Poland. In 70s and 80s, Inco (Full name: Zaklad Produkcyjny Aparatury Elektronicznej INCO) was known manufacturer of measurement devices, lab equipment and all "special" production e.g. for military, intelligence or security offices (also devices for communication, location of radio stations or radar applications), so I expected quite interesting things inside. It is still possible to get their old catalog on Silesian...

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Memory usage of different desktops in Linux (UPDATE: 32-bit)

2017-08-02 14:02:11,  In: Linux, Debian

While installing Linux on older machines a very popular question is "What desktop environment should I use?". With older machines, usually the biggest bottleneck is not a CPU, but RAM. Too small memory causes swapping, and it slows Linux even more. On the other hand, more free RAM makes system run faster. I decided to install Debian 9 (Jessie) in different configurations to measure memory usage of different desktop environments. All measures have been made on stock installation offered by Debian installer, by installing on virtual machine.

   Linux and memory

There is a large difference between memory reported by "free" and "htop" programs. It is coming from the method of using memory in Linux. The main rule here is that unused memory is wasted memory, so Linux uses free memory for buffers and caches, making system faster. While "free" shows buffers and caches memory as used, htop doesn't, only shows buffers on memory usage bar in blue/green color, while number indicator shows amount of RAM actually...

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Eee PC 900 as ultra-portable computer

2017-05-03 17:38:06,  In: Linux, Debian, Retrocomputing

Few weeks ago I bought a damaged Asus Eee PC, model with widescreen and Celeron processor. These computers were sold about 10 years ago as "netbooks", which were a transition between notebooks and tablets, when companies were not so sure that they will force users only to consume ad-filled "content" from the Internet. The computer has been repaired and now it works. I decided to make some use of it. Let's look what is inside:
- Intel Celeron processor at 900MHz
- 1GB of RAM in DDR2 SODIMM stick
- 4GB on-board SSD disk
- 16GB SSD disk using proprietary connector.
- Wi-fi, sound, Intel GMA950 video card, SD card reader and battery - all which modern laptop should have.



Previously, the computer had Windows XP installed, in its Home edition. There is a sticker for it so someone bought a license. Unfortunately, even fresh install of Windows XP on this machine works terribly, it is slow, overuses hard disk and suffers of few-second freezes. I decided to go with Linux as these...

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LibreOffice base: One macro to open them all

2017-04-22 15:39:42,  In: Hack, Database

Recently I was developing a simple database application in LibreOffice Base version 4.x. This is quite slow tool, but with a few modifications and tricks complex applications can be made.
Usually, database application consists of several forms supporting several tables opened from each other or common "switchboard" form. The problem in LibreOffice base is that it is not possible to easily make the "switchboard" form with buttons launching forms for other tables. There is no "macro wizard" to make it easily and most existing databases use extensions or hard-coded macros for it.
Officially, the only way to do it is by using Switchboard extension which is not much supported in later versions. Another way is to create macros for buttons. If you have 10 buttons opening 10 forms, you will have to make 10 macros connected to them, opening different forms. As in pure Open-Source programs, the only documentation is source code. Let's do it in more universal way: I inserted a target form name in ToolTip...

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