I bought those speakers as a real occasion. I was really surprised with their sound. Later on, it turned out that there should be small REMA sign on speakers cover. I searched for those in the internet, but nobody was selling it. I decided to recreate them by myself, but for that I needed high quality picture of it, from somebody who has such one. I must confess, people don't like to help ;)....

This JBL GO speaker was brought to me after it had been drenched by warm, summer rain. After quick look, it was obvious, that buttons are dead, but what was even worse, the BlueTooth module also had got his ass kicked. After discussion with the owner, we decided to not fix it, because cost would be higher than the same device from second hand. It laid almost two years as sporadically parts...

Somewhile ago I found a movie about reusing parts from old laptops. There were a few interesting ideas, but this one I decided to try by my self. It was not a discovery for my, that those cameras are connected internally via USB. As you may expect, you will not find USB plug inside, so to reuse it need to be recreted. And about this is this article.

One day, I got in my hand broken laptop...

This is one of the pearls in my collection. This project took me very long time, but it was worth to wait and now I can say: I'm proud of final effect. For the first time, I saw this model on my colleque desk at work, many years ago. I liked its small size. For playing music and voice on a deskspace you don't need huge power. I decided to buy this device for myself one day. Some time has...

This is another device from my friend collection. Some people really care about their equipment. This tape recorder - Aria from Unitra ZRK - is 42 years old and nothing indicates to be the last one. After such period of time I had clean it a bit, replace old rubber stripes, lubricate rollers, glue some parts, replace a few capacitors, clean switches and is ready to further usage.

What amazed...

Even in our clinic, sometimes staff get sick. This guy is our main player, so we had to take care of him on a first place.

For some time, there were some problems with it, that decreased pleasure of listening to it. The biggest and the most annoing was network hum. After measurements, it turned out, that power lines were affected. Naturally, first suspects were input filtering capacitors. I...

Previous owner of this power amplifier has broken this plastic holder. Recently I wanted to buy such part, but I gave up when I heard price of 30 PLN. Even new is not worth so much. Fortunately my father taught me how to handle caliper, a university how to draw a technical sketch, open source software gave me a tools for projecting such parts and modern technology gave 3D-printing machines....

When one observe the Internet, may get a unreal feeling that this is really something unique and valuable. Its price can get enormous level. I don't know if anyone buys it, but for me, its price is from the sky and not adequate to real quality. Somewhile ago I saw a nice document about designers and engineers working over this project. That wasn't easy project, because it involved a few...

I got this device as an old attic discovery from one of my friends. He claimed, there are a several problem, but mainly with driving a tape, not working rotation counter and crakling potentiometers. When I took off a plastic cover, it turned out that there will be much more work to do. I had to start with cleaning everything inside. I found some spiders corps and nets, dust and also rust and...

When I got know, that my private, small human is going to appear on this world, I realised that I need to do something to protect my speakers. Small fingers love to push speakers inside. Removal and renovations caused, that I was pushing this in a time until one day it turned out, it was too latend and being lazy is not profitable. Two speakers has been broken, so I decided to speed up with...

I had just finished previous power aplifier from Technics company (SU-V450) and immediately I got higher model SU-V500. This one I could name clover model, because it came to me from irish pub. As we know, nobody cares about such stuff in those places. Its role is just to work and play the music. As you can see from photos, this one don't have easy life though. Owner told me, that there is a...

There are plenty of old VU meters on polish market, but often they are to ugly to use them in new devices. The biggest problem is in backgroud (its color, style, etc). Recetly I had to fix one of this, but I hadn\'t two exactly same looking. I decided to use Inkscape and redesign it. One evening and there it is. Please take it and leave the comment below.

Original:
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Fixing power amplifiers from Technics company is always a pleasure because of theirs construction. This one, was brought to me with effects of unequal signal levels in channels and hoarseness sound on low volume level. After inspection and measurements, it turned out that its main pain was dirty and oxide connectors in number of switches and output relay. Cleaning in ultrasonic bath and...

In my job, we have de-soldering tool which we call "a cow" because of noise that is produced by working compresor. For my private purposes simple suction pump and a bit of copper wire is enough but people easily get use to luxury, so I decided to have such cow in my house as well. Basically, such de-soldering tool is a reverted hot air, with such a difference that compresor is turned on on...

That was supposed to be a quick fix and it was. My brother in law got this power amplifier on one of a local sales. The device has scratched metal case, so he don't want to keep it for himself. From electronic point of view it looked as it hasn't been opened since if had left factory. The biggest problem was in output selector switch. It was playing only in one position. As you can guess, on...

I got this power amplifier because protection circuit was always on and none of four channels play a sound. This is quite expect reaction. Inside of Sony XM3040 is a small IC from NEC, that provides couple of features: delayed speakers on, protection against direct current on output and against shorcircuit. Despite, none of those sympthoms occured, relays remained off. After measurements, it...

I bought this amplifier in the Internet forum. It was broken but metal case was in a very good shape. Most of those devices are badly scratched. This amplifier has very simple and well documented construction. I decided to take a risk. I bought it. When I opened it turned out that it hadn't been serviced by any amateur. All part were original. Big plus.

I have been told, by previous owner,...

I got this device from my friend. It was laying in his garage and he had no concept what to do with it. He even wasn't sure if its still working. It took about a year when finally I had time to look into it. I wanted to check its condition, but I hadn't speaker with appropriate jack, so I took of metal shield and soldered loose wires directly to output PCB. I was amazed when it turned out that...

Since I was a little kid, I was interested in C64. Some while ago I was wondering how does this analogue modulator, providing signal to TV, works. I searched the Internet, but I didn't find. Recently, by coincidence, I found it and decided to put it here. I hope it will be useful for someone.

In the Internet are many pages about how to get better video signal from this old computer.

I grew up in 80's and 90's. Having a remote controlled car in that time was a dream of all boys and also not available for most of them. Those who have it was king of neighbourhood. I was also dreaming about it and after many years I made it come true. Of course, since a few years you can buy such toy in shops but I wouldn't be myself if just go and buy one. The biggest satisfaction will give...

In my basement I have found one old project. It was remote controller with Attiny2313 in transmitter and Atmega8535 in receiver. It was using some dummy RF433MHz modules and wasn't able to send data properly. Probably that is way it was in basement ;). After a few years I decided to make it work by replacing those modules with something more intelligent. I decided to use RFM-70D. To communicte...

Some while ago I got broken power amplifier WS503 polish factory Unitra. On the beggining I thought replacing main fuse will be all I need to do. It turned out that really fuse was burnt, but from speakers protection circuit. When I opened a case and spent some time with multimeter I realized that also one power circuits was broken down. I started work and after eight evenings, everything was...

Every speaker have its own life time. So it is natural, that after some time we need to buy new one. Now a days most of equipment is designed in that way, to be thrown out after maximum 5 years. I really don't like that fact, a specially when I have some old and good stuff. It is not that hard to replace broken part with new crappy one and after some short period of time spent another money...

I was born in 80's and grew up in 90's, that is way technic from that time is really close to me and have sentimental meaning for me. When I got Unitra's power amplifier to service for the first time, I hadn't enough knowledge to deal with it. So, after replacing burnt transistors and fuses, which burnt out after next try of turning it on, I gave up when costs of repair grew to much.

One day I got graphic LCD from old, broken device. I didn't know much about this model except that if is black/green one. When I dug it out from silicon glue it turned out, that it had original producer label. I looked in the Internet and I found datasheet. It looked very comprehensive but also a bit complicated. I cound easly read out from it how to set up all registers. I decided, that if I...

As many students in Poland, I also had to take second term of exams on my university. We used to call it "Septeber campain", because it was in September. I must say, I'm glad of this fact. I really didn't want to learn during my summer holidays, but somehow I found strenghts to learn. I read series of scripts from one of profesors (Władysława Ciążyńskiego), which in simple and clear way...

I made this device in August 2003. An idea for this toy came to my mind when I was lying sick in a bed. It is just simple flashing effect. When I recovered I decided to send it to electronic magazine "Elektronika dla Wszystkich" where it was published :D.

What is this for?

Answer is simple: to make happy or at least make a person smile to whom it is presented. This device was built two years...

Some while ago company Microchip released ICD2 programmer (during writing this article there is ICD3 on market). It is universal ISP (In System Programmer), what means that if we want to change program in our chip, we don't need to solder it out. All we need is to plug small connector into device. Its the biggest advantage is wide range of programed chips. For debug purposes it includes JTAG...

I built this project as task on one of my university classes. Its purpose was to demonstrate idea of working hearing aid. When I got a score I turned it into 6 point equlizer.

This is a schematic of device:

Building equalizer we must ask ourself a question about how many frequencies we wnat to equalize and in what range. Number of points depends on how many frequency we choose. Let's...

This is the smalest robot, that I have ever built. On one of the websites I found picture of other robot, that become an inspiration for me. Unfortunately, I didn't achieve such small scale but still I'm proud of final efect.

Previous version

Presented version is not first one. It is a second one. In first one its weight point was very high what made him very unstable and his brain was...

Many years ago I saw a robot in TV. Well, it was only a hand on moving platform. One thing I remember from this show was that it took a glass of water from the table and move to another. That time, I was too young to build such a toy. What I did was much smaller and weaker. I didn't have skills and tools to build something better.

Now, after many years, when I got a bit plexiglass garbage, I...

Its name comes from its maximum speed. It is my first remote controlled robot. Since I was kid I liked that kind of toys, but I grew up in 80's, 90's when remote controlled cars and tanks were not easily available for all kids. Then I become a teenager and it wasn't proper to play with such toys. Fortunately, when you are an electronic engineer you can build it by your own.

In this model I...

Theory of controlling values are very complex. It depends on many factors e.g. what do we want to control (temperature, rotation, light level, etc.) and how do we control it (valves, relays, motors, etc.). All those things are far from ideal models, so it not so easy to describe easly dependency between them. Generally, we have a few types of controllers:

• PI – proporcional-integrating
• PD...