Parts

678 Articles

Buck Converter Takes 8V To 100V

September 17, 2023 by 40 Comments

For those living before the invention of the transistor, the modern world must appear almost magical. Computers are everywhere now and are much more reliable, but there are other less obvious changes as well. Someone from that time would have needed a huge clunky machine like a motor-generator set to convert DC voltages, but we can do it with ease using a few integrated circuits. This one can take a huge range of input voltages to output a constant 5V.

The buck converter was designed by [hesam.moshiri] using a MP9486 chip. While it is possible to use a multipurpose microcontroller like something from Atmel to perform the switching operation needed for DC-DC converters, using a purpose-built chip saves a lot of headache. The circuit was modified a little bit to support the higher input voltage ranges and improve its stability and reliability. The board is assembled in an incredibly tiny package with inputs and outputs readily accessible, so it would be fairly simple to add one into a project rather than designing it from scratch.

Even though buck converters, and other DC converters like boost and the mysterious buck-boost converter, seem like magic even to us, there is some interesting electrical theory going on if you’re willing to dive into the inner workings of high-frequency switching. Take a look at this explanation we featured a while back to see more about how buck converters, the more easily understood among them, work.

Clock Hack Gives DEC Rainbow A New Lease On Life

September 12, 2023 by 21 Comments

In retrocomputing circles, it’s often the case that the weirder and rarer the machine, the more likely it is to attract attention. And machines don’t get much weirder than the DEC Rainbow 100-B, sporting as it does both Z80 and 8088 microprocessors and usable as either a VT100 terminal or as a PC with either CP/M or MS-DOS. But hey — at least it got the plain beige box look right.

Weird or not, all computers have at least a few things in common, a fact which helped [Dr. Joshua Reichard] home in on the problem with a Rainbow that was dead on arrival. After a full recapping — a prudent move given the four decades since the machine was manufactured — the machine failed to show any signs of life. The usual low-hanging diagnostic fruit didn’t provide much help, as both the Z80 and 8088 CPUs seemed to be fine. It was then that [Joshua] decided to look at the heartbeat of the machine — the 24-ish MHz clock shared between the two processors — and found that it was flatlined.

Unwilling to wait for a replacement, [Joshua] cobbled together a temporary clock from an Arduino Uno and an Si5351 clock generator. He connected the output of the card to the main board, whipped up a little code to generate the right frequency, and the nearly departed machine sprang back to life. [Dr. Reichard] characterizes this as a “defibrillation” of the Rainbow, and while one hates to argue with a doctor — OK, that’s a lie; we push back on doctors all the time — we’d say the closer medical analogy is that of fitting a temporary pacemaker while waiting for a suitable donor for a transplant.

This is the second recent appearance of the Rainbow on these pages — [David] over at Usagi Electric has been working on the graphics on his Rainbow lately.

Intel’s Chips Light The Way To Faster Processor Arrays

September 7, 2023 by 19 Comments

It’s very likely indeed that whatever you are reading this on will have a multi-core processor. They’re now the norm, but the path to they octa-or-more-core chip in your phone has gone from individual processors with PCB interconnects through many generations of ever faster on-chip ones.

But what if your power needs are so high-end that you need more cores that can be fitted on one chip, but without the slow PCB interconnect to another? If you’re Intel, you develop a multi-core processor with an on-chip photonic interconnect. It talks to the neighboring ones in its cluster at full speed, via light.

The chip in question isn’t one you’ll see in a machine near you, instead it’s inspired by the extremely demanding requirements for DARPA’s HIVE graph analytics program. So this is a machine for supercomputers in huge data centers rather than desktop computers, it will be assembled into multi-die packages with that chip-to-chip optical networking built in. But your computer today is the equal of a supercomputer from not that many years ago, so never say you won’t one day be using its descendant technologies.

If You Aren’t Making Your Own Relays…

September 3, 2023 by 46 Comments

We’ve all been there. Someone will say something like, “I remember when we had to put our programs on a floppy disk…” Then someone will interrupt: “Floppy disk? We would have killed for floppy disks. We used paper tape…” After a few rounds, someone is talking about punching cards with a hand stylus or something. Next time someone is telling you about their relay computer, maybe ask them if they are buying their relays already built. They will almost surely say yes, and then you can refer them to [DiodeGoneWild], who shows how he is making his own relays.

While we don’t seriously suggest you make your own relays, there are a lot of fun techniques to pick up, from the abuse of a power drill to the calculation of the coil parameters. Even if you don’t learn anything, we get the desire to make as much as you can.

Continue reading “If You Aren’t Making Your Own Relays…” →

A Hobson’s Coupler Leads To A Weird Engine

August 10, 2023 by 19 Comments

You want to join two shafts. What do you need? A coupler, of course. If the shafts don’t line up, you might consider an Oldham coupler. But what if the shafts are at a 90-degree angle to each other? Then you need a Hobson’s coupler. [Robert Murray-Smith] has the 3D printed hookup for you and a video that you can see below.

The part isn’t all 3D printed, though. You do need some bearings and steel rods. [Robert] proposes using this to couple a windmill’s blades to a generator, although we assume some loss is involved compared to a standard shaft. However, we’ve heard that the coupler, also called a Hobson’s joint or a stirrup joint, is actually pretty efficient. However, you rarely see these in practice because most applications will use a gear train employing a bevel gear.

While it may not be practical, the second video below shows an elbow engine that would look undeniably cool on your desk. By making some changes, you can create a Cardan joint which happens to be half of what you think of as a universal joint. The Hobson coupler and the Cardan joint seem to be made for each other, as you’ll see in the video.

We aren’t sure what we want to make with all these mechanisms, but as [Robert] points out, with new materials and techniques, these mechanisms might have a role to play in future designs, even though they have been mostly discarded.

There are, of course, many kinds of couplings. Then again, not all useful joints have to move.

Continue reading “A Hobson’s Coupler Leads To A Weird Engine” →

Easyeda2KiCad: Never Draw A Footprint Again

August 8, 2023 by 38 Comments

What if I told you that you might never need to draw a new footprint again? Such is my friend’s impression of the tool that she’s shown me and I’m about to show you in turn, having used this tool for a few projects, I can’t really disagree!

We all know of the JLCPCB/LCSC/EasyEDA trio, and their integration makes a lot of sense. You’re expected to design your boards in EasyEDA, order the components on LCSC, and get the boards made by JLCPCB. It’s meant to be a one-stop shop, and as you might expect, there’s tight integration between all three. If there wasn’t, you’d be tempted to step outside of the ecosystem, after all.

But like many in this community, I use KiCad, and I don’t expect to move to a different PCB design suite — especially not a cloud one. Still, I enjoy using the JLCPCB and LCSC combination in the hobby PCB market as it stands now, and despite my KiCad affinity, it appears that EasyEDA can help me after all!

Continue reading “Easyeda2KiCad: Never Draw A Footprint Again” →

The Simplest Curve Tracer Ever

August 2, 2023 by 15 Comments

To a lot of us, curve tracing seems to be one of those black magic things that only the true wizards understand. But as [DiodeGoneWild] explains, curve tracing really isn’t all that complicated, and it doesn’t even require specialized test instruments — just a transformer, a couple of resistors, and pretty much whatever oscilloscope you can lay your hands on.

True to his handle, [DiodeGoneWild] concentrates on the current-voltage curves of Zener diodes in the video below, mainly as a follow-up to his recent simple linear power supply project, where he took a careful look at thermal drift to select the best Zener for the job. His curve tracer is super simple — just the device under test in series with a bunch of 10-ohm resistors and the secondary winding of a 12-volt transformer. The probes of his oscilloscope — a no-frills analog model — go across the DUT and the resistor, and with the scope in X-Y mode, the familiar current-voltage curve appears. Sure, the trace is reversed, but it still provides a good visualization of what’s going on. The technique also works on digital scopes; just be ready for a lot of twiddling to get into X-Y mode and to get the trace aligned.

Of course it’s not just diodes that can be tested with a curve tracer, and [DiodeGoneWild] showed a bunch of other two-lead components on his setup. But for our money, the neatest trick here was using a shorted bridge rectifier to generate a bright spot on the curve to mark the zero crossing point. Clever indeed, and pretty useful on a scope with no graticule.

Continue reading “The Simplest Curve Tracer Ever” →