Adrian’s electronics blog

Electronics projects | Microcontroller projects | Teardowns | Reviews | Tutorials | Random tech babble

Is it even worth repairing consumer goods nowadays?

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30 years ago… Yes. Now not so much. Take for example a repair of a Panasonic DMR-BWT720 blu-ray recorder which I was handed for free as it had failed and had been replaced with a newer model. The fault – freezes / runs slow and fails to record sometimes. If it does record the image breaks up. Simple – it’s just bad reception right? No.

To cut a long story short I noticed a lot of noise coming from the HDD mainly repeated ticking sounds. Now with me being an IT professional I knew this sounded like a failing HDD and I know what a knackered HDD sounds like. I whipped the top cover off and removed the HDD and ran some read only tests on it. The drive failed with ‘too many bad sectors encountered’ error as suspected.

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Sanyo 1970’s LED clock / radio resurrection (well sort of)

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In the quest to make something useful out of a load of old junk I’ve found in my cupboards I came across my old clock radio I’ve had since 1978 a while back and decided to do something with it rather than throw it out. It actually worked but it had an ‘accident’ with the floor a few years ago which had broken the casing and cracked the main PCB.

1970’s clock in new casing with Arduino based temperature display on 7 segment LED’s

I have no idea why I just didn’t throw it out then but I had replaced it with a cheapo clock off ebay which projected the time onto the ceiling with some superbright LED’s and mini LCD’s. Quite innovative but that piece of crap lasted a few months before breaking prompting me to replace it yet again. Well the second replacement failed by randomly corrupting the display and resetting itself. Not ideal if you want to set up an alarm that can reliably wake you up. Acctim? Craptim more like.

On one of my earlier posts I made an alarm clock using an 8051 microcontroller but the alarm was unsatisfactory so in order to avoid more cheap Chinese electronics that doesn’t work I decided to make something out of what remained of the 1970’s alarm clock. The clock PCB was functional as was the LED display but it was very dim and had small segments. It also drew a lot of current (nearly 600mA) and the clock IC, TMS1944AN2L got very hot. I had a Fairchild Semiconductor FCS8000 LED module which is also 1970’s vintage salvaged from another clock but I had a datasheet for this which showed that it is a low current, high brightness module. It draws much less current (and has a bigger display) than the old LED display.

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Ebay transistor tester testing

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I bought myself one of those cheap transistor testers off ebay based on the Ardutester at https://forum.arduino.cc/index.php?topic=164112.0 which basically is an Arduino project that someone made which the Chinese commercialized and ripped off. It’s actually a great bit of kit but it’s clearly based on an Arduino project that was never intended to be a commercial product.

The Ebay ‘transistor tester’ which does a whole lot more than just test transistors

With the Arduino and good programming and electronics knowledge you can make an end product that rivals a commercial product. Take for example the Ardutester; an open source project that tests electronic components and displays the results on a character LCD. It’s a fantastic project and the designer made all the source code and hardware schematics available for others to make. Seemingly someone in China saw this as a potential to make money, took the source code and improved it then sold it as a commercial product. I’d imagine the creator of the original product would be pissed but I guess there’s nothing you can do about it.

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Playing with an 8051 microcontroller

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I’ve been using the Arduino for a while now and made a few projects but at work we use the 8051 as the primary micro for our in house equipment. Yeah it’s outdated but Silicon Labs have taken the original 8051 design and vastly improved it with clock speeds of 100Mhz. It can easily outperform an Arduino and technically is a more capable processor.

However support is limited and its for professional programmers only whereas the Arduino is more for hobbyists. Knowledge of the CPU and in depth knowledge of C is required to get anywhere with this. I decided to buy an Atmel version which is more or less based on the original Intel design but it does run at 24Mhz. It also comes in a DIP package too so is ideal for breadboard and veroboard projects.

I found that development kit and software was expensive unless you used the outdated SDCC compiler or BASCOM. Support was lacking and I struggled to make anything useful with it. Compared to the Arduino with it’s libraries etc you don’t need to know how the AVR chip works and there’s loads of help out there.

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A WIFI spectrum analyzer and Talk-Talk routers suck A$$

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A close relative of mine has been having lots of wifi connection issues over the last few months but just on a couple of devices. A scan of the wifi neighborhood showed only a couple of signals from adjacent houses which were too weak to cause a problem.

I tried changing the channels, 150 or 300 bandwidth modes and even tried dropping to 54G compatibility. The problem would be fixed but return a few days later. I tried disabling the wifi adaptor in one of the affected laptops and used a USB adaptor instead. I couldn’t swap the router as this was needed for IPTV (talk talk) and my replacement didn’t support it. Same problem with different adaptors. What was going on? Mobile phones and tablets were fine; just the two Windows 7 / 10 devices refused to work. I needed to scan for interference and here’s where the Arduino came in.

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First useful Arduino project – NIMH battery tester

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***Updated*** now version 5 which has a vastly improved display layout and better voltage reading accuracy. Download can be found towards the bottom of this page.

During my clearout of old junk I came across an LCD display fitted into a small plastic case with a PC parallel cable attached which was originally used for a PC status display using LCD smartie. This was used on my old, old, PC (Pentium 4) to display system status messages and music track info from winamp.

As my new PC lacked a parallel port (yeah I could have added one but no PCI slots, just PCI-E) this was relegated to the junk cupboard. So what shall I do with this display and case?

Arduino based NIMH battery tester (image)
Arduino based NIMH battery tester

Well I have a pile of rechargeable AA batteries of various ages and I came across this Arduino based battery tester which looked ideal to test said batteries. Now it just needed a few simple modifications; I added an LED that flashes to get attention when the test is complete and changed some of the screen messages. Simple stuff. After all I was just starting out with the Arduino and I felt this was a great starter project.

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Clear-out day – and PSU refurb

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A few weeks ago i decided it was time I got rid of some old shite I’ve been keeping for years. I also decided to make this blog and some of my early electronics projects I have featured on this site. Not that they are any use to me nowadays but I want to keep them well, you know just because. The historical and test equipment pages will fill you in on this.

Some stuff was worth improving and refurbishing. Take this bench PSU I made around 25 years ago which was the most useful thing I made as in it had a purpose and was used often. Well actually I made two bench power supplies back then. The original wooden cased model was lacking in voltage and current so I had made another using a basic regulator with a couple of 2N2055 series pass transistors stuffed into a BBC Micro external HDD case. As all parts were salvaged from scrap save a few knobs and switches I didn’t have much flexibility with the design.

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