College Gives You Practical Electronics

September 3, 2024 by Al Williams 28 Comments

While classroom learning isn’t for everyone, one awesome benefit of the Internet is that you have a variety of college classes available to you, even if they aren’t for credit. You can virtually audit classes from institutions around the world on just about any topic you can think of. Of course, the topic we think of is practical electronics and that happens to be the title of a class from [Dr. Bill Newhall] of the University of Colorado. You can watch the first part in the video below. So far, there are two lectures available but more are coming as the class is ongoing right now.

[Dr. Newhall] is one of us. He’s a ham radio operator and a pilot, as well as an electrical engineer. This class is aimed at others who need to understand electronics in another context. It reminded us of the genesis of one of our favorite books — also from a professor — The Art of Electronics.

The course material promises to cover topics ranging from solar and battery power sources, power conversions, IoT and RF communications, sensors, and DC motor control. Of course, there will also be sections on microcontrollers and associated hardware.

Just like a real class, the first lecture has a lot of housekeeping information, but you might want to skim it anyway. But if you want to get to the electronics, the second video won’t disappoint. While it covers a lot of ground that is probably familiar to most Hackaday readers, it is a good review and there’s more coming in the future lectures.

With all the resources online, you can easily hack your own degree plan together. Having access to instructors like [Dr. Newhall] is exactly the point we were making about how the Internet allows you to leverage the best educational opportunities no matter where you are.

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3D Printering: Klipper, The Free 3D Printer Upgrade

August 29, 2024 by Al Williams 33 Comments

I have several 3D printers, and I’ve always been satisfied with using either Repetier or Marlin on all of them. There are a few other firmware versions that could run on my hardware, but those two have been all I’ve needed. Sure, it was painful for a while having to juggle features to fit the firmware image onto the smaller microcontroller boards. Now that Marlin supports big 32-bit boards however, that hasn’t been a problem. But recently, I’ve been on a program to switch everything to Klipper.

In this post, I’ll tell you why I did it and give you some data about why you might consider it, too.

The Landscape

Marlin is written in C and burned into a 3D printer’s flash memory. It does a lot. It receives G-code commands, interprets them, and translates them to meaningful actions on the hardware. Modern versions handle automatic transformations to account for lumpy beds, input shaping to reduce shaking, and linear advance to produce better prints.

It might seem simple to control a 3D printer, but there are lots of little details to take into account. For example, if you are moving the head between two XY coordinates and you expect a certain flow rate, then you have to figure out how fast to turn the steppers to get the right amount of plastic out over that time. You also may have to retract before you start a move, make sure temperatures are stable, and transform the actual coordinates based on bed leveling data. There’s a lot going on.

Klipper does the exact same job, but it does it differently. On the 3D printer board is a tiny piece of software that does very little. It’s a bit like a device driver for the printer. All by itself, it does nothing. But it can handle very basic commands that describe how to move the machine.

All the rest of the processing you expect to happen now runs on some Linux computer. That is very often a Raspberry Pi, but it could be a spare laptop, your desktop computer, or anything that will run a reasonable Linux install. Several vendors even sell single-board computers with touchscreens made specifically for running this part of Klipper.

However, even though a screen is nice, you don’t really need it. I’ll talk about that more later.

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Everything You Wanted To Know About Early Macintosh Floppies

August 26, 2024 by Al Williams 30 Comments

Using a disk drive today is trivial. But back “in the day,” it was fairly complex both because the drives were simple and the CPUs were not powerful by today’s standards. [Thomas] has been working on a 68000 Mac emulator and found that low-level floppy information was scattered in different places. So he’s gathered it all for us in one place.

Low-level disk access has a lot of subtle details. For example, the Mac calibrates its speed control on boot. If your emulated drive just sets the correct speed and doesn’t respond to changes during calibration, the system will detect that as an error. Other details about spinning disks include the fact that inner tracks are shorter than outer track and may require denser recordings. Laying out sectors can also be tricky since you will lose performance if you, for example, read sector one and then miss sector two and have to wait for it to come back around. Disk sectors are often staggered for this reason.

Adding to the complexity is the controller — the IWM or Integrated Woz Machine — which has an odd scheme for memory mapping I/O. You should only access the odd bytes of the memory-mapped I/O. The details are all in the post.

In a way, we don’t miss these days, but in other ways, we do. It wasn’t that long ago that floppies were king. Now it is a race to preserve the data on them while you still can.

V-Slot Wheels Or Linear Rails?

August 25, 2024 by Al Williams 45 Comments

In the early days of 3D printers, most builds used smooth rods and bearings that rode on them. But these days, printers are shipping with either V-slot extrusions with Delrin wheels or linear rails. Which is best? Everyone seems to have an opinion, but [Spencer] decided to compare them using some well-defined experiments, and he shares his results in the video below.

Common wisdom is that linear rails create a better print quality, but [Spencer] didn’t really find that much difference. He does admit, however, that he isn’t an expert on setting up linear rails, so perhaps there’s something he could have done better. He did note that the rails were quieter but that, for both cases, the noise generated by the moving rails was only a small fraction of the total noise generated by the printer. The rails were also more stable in terms of resonance. Input shaping can help overcome that, though, so it probably isn’t that important in a modern printer.

What do you think? Are linear rail upgrades worth it? Let us know in the comments. We’ve been 3D printing long enough that we are hard-pressed to complain much about any of the prints we produce today on printers that cost a fraction of what we spent on our first ones.

Of course, you could go with string. Putting rails together with or without slots is its own art form.

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Simulating Air Flow For 3D Printing

August 25, 2024 by Al Williams 1 Comment

You’ve probably heard that a 3D printer is capable of producing its own replacement parts. Sometimes, that even includes upgraded or improved versions of the parts it was originally built with. But sometimes, it’s hard to figure out what improved really means. Think about air ducts that cool the part after printing. In theory, it should be easy to design a new duct. But how does it perform? Empirical testing can be difficult, but [Mike] shows how you can simulate the airflow so you can test design changes and validate assumptions before you print the actual part.

Of course, this wouldn’t only apply to printer ducts. You might also get some tips if you want to model airflow for PC cooling, hot air soldering, or other air-related projects. The free version of the software has some limitations, but it was surprisingly capable.

We also enjoyed how [Mike] used fluid to visualize the actual patterns and compared it to the simulation. The trick is using a compound from a kid’s science project kit, and it seems to work very well. Of course, you could just grab your smartphone. This might be worth thinking about if you are building a laser cutter air assist, too.

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Tech In Plain Sight: Speedometers

August 22, 2024 by Al Williams 29 Comments

In a modern car, your speedometer might look analog, but it is almost certainly digital and driven by the computer that has to monitor all sorts of things anyway. But how did they work before your car was a rolling computer complex? The electronic speedometer has been around for well over a century and, when you think about it, qualifies as a technlogical marvel.

If you already know how they work, this isn’t a fair question. But if you don’t, think about this. Your dashboard has a cable running into it. The inner part of the cable spins at some rate, which is related to either the car’s transmission or a wheel sensor. How do you make a needle deflect based on the speed?

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Farewell Magnetic Stripe

August 21, 2024 by Al Williams 114 Comments

For decades, the magnetic stripe has been ubiquitous on everything from credit cards to tickets to ID badges. But the BBC reports — unsurprisingly — that the mag stripe’s days are numbered. Between smartphones, QR codes, and RFID, there’s just less demand for the venerable technology.

IBM invented the stripe back in the early 1960s. The engineer responsible, [Forrest Parry], was also involved in developing the UPC code. While working on a secure ID for the CIA, his wife suggested using an iron to melt a strip of magnetic tape onto the card. The rest is history.

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