Electronics and technology blog    /    Articles    /    Notes in the margins

Not long ago, I showed a new version of an electronic load. In a sense, it’s a downgrade—a step backward rather than forward—but it’s not that simple, so I decided to put together a short article.

Yes, today this isn’t a review or an article, but a story. It’s about the TEC-80K electronic load, which is fairly popular and well known, and about my new device based on this controller.

Today, this isn't a review so much as a look back at my experience searching for, choosing and buying a tablet from one of our online stores, along with a few recommendations based on what I learned along the way. The tablet in question is the Microsoft Surface Pro 9.

Today, the Verkhovna Rada of Ukraine passed two bills, No. 11258 and No. 11259, in their second reading and as a whole. They are intended to restore the energy infrastructure and clear mines from Ukrainian territory as quickly as possible.

I haven’t been posting much lately, and someone even asked if everything was okay with me. Unfortunately, I’ve had a lot on my plate, and I’d like to tell you about some of it today, since it turned out to be relevant to buyers and interesting to me.

In today’s world, there are many electronic devices, and progress is driving them toward ever-smaller sizes. Repairing them with a “grandpa’s” soldering iron is becoming increasingly difficult, though there are still areas where one can come in handy. But today we’re not talking about soldering irons. We’re looking at much more sophisticated equipment, intended not so much for home use as for professional applications.

About a month and a half ago, I reviewed an inexpensive power bank case that was convenient, affordable, capable of delivering up to 22 W, and supported fast-charging protocols. But ever since then, I’ve wanted not only to fit it with the highest-capacity batteries possible, but also to make a few improvements.

I’m often asked about various things, and questions about changing a power supply’s output voltage are probably among the most common. Today I’d like to explain the subject a little; hopefully it will help someone.

I can’t even remember when or how this little board came into my possession, but it was clearly a long time ago. It sat around for years until I happened to come across it and decided, just out of curiosity, to figure it out and repair it. Read on to see how that went.

I don't think I'm far off if I say that quite a lot of people have had electronic devices fail because of overvoltage. It happens for various reasons, but the result is almost always the same: the power supply burns out. Just as there are different causes, there are also different ways to deal with the problem, and that's what we'll talk about today.

Another power supply has come my way, this time from an SVEN SB-550 active speaker system. The repair is fairly routine, but still interesting in its own way, and involves replacing the PWM controller with a non-original part.

This review—or article, whichever you prefer—is a continuation of my write-up on modifying a power supply to turn it into a low-voltage UPS. Last time, I covered a 150 W power supply and complained that the LRS-150 turned out not to be a very good fit for this purpose. So, let’s see how its bigger brother fares.

Today’s article is about repairing—or perhaps restoring—two power supplies from a mini PBX. These units are quite unusual and use some rather unconventional circuit designs, so this will be a long and fairly detailed article. I hope it will be useful for beginners and interesting for experienced repair technicians as well.

I hadn’t even thought about writing up this repair. Then I figured I’d just write a little and add a few photos. But I got carried away, and it ended up becoming an article about how power supplies behave when the voltage is too high, with a little extra theory about the circuitry of the chips.

In my previous article, I wrote that repairing power supplies is usually not cost-effective, and even gave examples of cases where it really does make sense. But I just remembered a simple power supply I worked on fairly recently that’s a good example of when a repair is worthwhile.

Some time ago, I was sent several different pieces of equipment to repair, including a couple of power supplies. The repairs themselves weren’t particularly difficult, but they covered a fairly wide range of common failures. I’d like to use them as examples to show what’s what, what’s best avoided, and what you should definitely do.

First, I should say that I know exactly how this charger works. It’s strange in its own right, but it’s probably better to look at the photos and read the short description. The real surprise comes at the end—I’m almost certain you’ve never seen anything like it.

I never thought I'd have to write a post like this, but I wanted to warn you about the problems you may run into when using Meest-express.