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Linear Power Supply’s Current Limiter Is A Lesson In Simplicity

June 5, 2023 by 5 Comments

Here at Hackaday we really like to feature projects that push the limits of what’s possible, or ones that feature some new and exciting technology that nobody has ever seen before. So what’s so exciting about this single-voltage linear power supply? Honestly, nothing — until you start looking at its thermally compensated current limiting circuit.

This one is by [DiodeGoneWild], who you’ve really got to hand it to in terms of both the empirical effort he went through to optimize the circuit, as well as the quality of his explanation. The basic circuit is dead simple: a transformer, a full-wave rectifier, an LD1085 adjustable regulator — a low-dropout version of the venerable LM317 — and associated filter caps and trimmer pot to adjust the output between 2.2 and 5.5 volts.

The current limiting circuit, though, is where things get interesting. Rather than use an op-amp, [DiodeGoneWild] chose a simple discrete transistor current-sense circuit. To make it less susceptible to thermal drift, he experimented with multiple configurations of resistors and Schottky diodes over a wide range of temperatures, from deep-freeze cold to hair-dryer-in-a-box hot. His data table and the resulting graph of current versus temperature are works of art, and they allowed him to make sensible component selections for a fixed 250-mA current limit with a reasonably flat thermal response.

As for construction, it’s all classic [DiodeGoneWild], including a PCB with traces ground out with a Dremel and a recycled heat sink. He also dropped a couple of interesting build techniques, like adding leads to turn SMD tantalum caps into through-hole components. The video below shows all the build details along with the exhaustive breadboard testing.

From taking on a potentially risky magnetron teardown to harvesting lasers from headlights, there’s always something to learn from a [DiodeGoneWild] video.

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A Real-World Experience In PCB Dye-Sub Printing

June 4, 2023 by 8 Comments

We all love PCB artwork, but those who create it work under the restriction of having a limited color palette to work with. If it’s not some combination of board, plating, solder mask, and silk screen, then it can’t easily be rendered on a conventional PCB. That’s not the end of the story though, because it’s technically possible to print onto a PCB and have it any color you like. Is it difficult? Read [Spencer]’s experience creating a rainbow Pride version of his RC2014 modular retrocomputer.

Dye-sublimation printing uses an ink that vaporizes at atmospheric pressure without a liquid phase, so a solid ink is heated and the vapor condenses back to solid on the surface to be printed. Commercial dye-sub printers are expensive, but there’s a cheaper route in the form of an Epson printer that can be converted. This in turn prints onto a transfer paper, from which the ink is applied to the PCB in a T-shirt printing press.

[Spencer] took the advice of creating boards with all-white silkscreen applied, and has come up with a good process for creating the colored boards. There is still an issue with discoloration from extra heat during soldering, so he advises in the instructions for the kit to take extra care. It remains however a fascinating look at the process, and raises the important point that it’s now within the reach of perhaps a hackerspace.

Regular readers will know we’ve long held an interest in the manufacture of artistic PCBs.

ADATA SSD Gets Liquid Cooling, But Not Everyone’s Convinced

June 3, 2023 by 19 Comments

Solid-state drives (SSDs) were a step change in performance when it came to computer storage. They offered incredibly fast seek times by virtue of dispensing with solid rust for silicon instead. Now, some companies have started pushing the limits to the extent that their drives supposedly need liquid cooling, as reported by The Register.

The device in question is the ADATA Project NeonStorm, which pairs a PCIe 5.0 SSD with RGB LEDs, a liquid cooling reservoir and radiator, and a cooling fan. The company is light on details, but it’s clearly excited about its storage products becoming the latest piece of high-end gamer jewelry.

Notably though, not everyone’s jumping on the bandwagon. Speaking to The Register, Jon Tanguy from Crucial indicated that while the company has noted modern SSDs running hotter, it doesn’t yet see a need for active cooling. In their case, heatsinks have proven enough. He notes that NAND flash used in SSDs actually operates best at 60 to 70 C. However, going beyond 80 C risks damage and most drives will shutdown or throttle access at this point.

Realistically, you probably don’t need to liquid cool your SSDs, even if you’ve got the latest and greatest models. However, if you want the most tricked out gaming machine on Twitch, there’s plenty of products out there that will happily separate you from your money.

A Simple Guide To Cams

May 31, 2023 by 10 Comments

With the availability of precision controllable actuators, it’s easy to overlook the simple but versatile mechanisms that got us here. In the video after the break, [Teaching Tech] explores the basics of cams and how to use them in your projects.

Cams are used to convert rotation into linear motion, and are probably best known for their use in engines and locking mechanisms. [Teaching Tech] first goes over the basic design and terminology in CAD, and demonstrates it’s use with a cam follower, locking mechanism, cam plate, and a knob that snaps to predefined positions. Of course a cam shape is not limited to a single lobe, but can have multiple lobes of various heights to create different motion patterns.

Cams are especially useful when you need to operate multiple mechanisms from a single input drive, as [Teaching Tech] demonstrates with the 3D printed automaton of a polar bear attempting to swipe a seal. We’ve also seen cams on a mechanical 7-segment display, and they were used to safely fire machine guns through aircraft propellers up to the 1950’s.

So next time you’re thinking adding another actuator to a project, take a moment to consider if a cheap and simple cam could do the job.

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The Wizard Of Semiconductors

May 22, 2023 by 19 Comments

If you have three hours and you want to learn the fundamentals of semiconductors, [Tiny Tapeout] has something for you: An introduction to SiliWiz. You’ll also need the SiliWiz software (or use it online), which resembles the kind of tools that chip designers use but is meant for students to use as a learning tool

Using SiliWiz, you create layers on a virtual device, and you can use Spice to view the results. The tutorial is meant to be high-level and is suggested for students aged 14 or over (but we liked it and we are quite a bit older than that). Some more advanced material is also available at the same site.

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Op-Amp Challenge: MOSFETs Make This Discrete Op Amp Tick

May 20, 2023 by 9 Comments

When it comes to our analog designs, op-amps tend to be just another jellybean part. We tend to spec whatever does the job, and don’t give much of a thought as to the internals. And while it doesn’t make much sense to roll your own op-amp out of discrete components, that doesn’t mean there isn’t plenty to be learned from doing just that.

While we’re more accustomed to seeing [Mitsuru Yamada]’s digital projects, he’s no stranger to the analog world. In fact, this project is a follow-on to his previous bipolar transistor op-amp, which we featured back in 2021. This design features MOSFETs rather than BJTs, but retains the same basic five-transistor topology as the previous work, with a differential pair input stage, a gain stage, and a buffer stage. Even the construction of the module is similar, using his trademark perfboard and ultra-tidy wiring.

Also new is a flexible evaluation unit for these discrete op-amp modules. This very sturdy-looking circuit provides an easy way to configure the op-amp for testing in inverting, non-inverting, and transimpedance mode, selecting from a range of feedback resistors, and even provides a photodiode input. The video below shows the eval unit in action with the CMOS module, as well as highlights the excellent construction [Mitsuru Yamada] is known for.

Looking for some digital goodness? Check out the PERSEUS-8, a 6502 machine we wish had been a real product back in the day.

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Big Tactile Button Is Silly But Cool

May 18, 2023 by 8 Comments

Every hacker is familiar with those teeny little tactile buttons that are so enjoyable to click over and over again. [ROBO HUB] has built a giant version as a tribute, and it works just like the real thing!

The giant button has been scaled up 20 times compared to the original. For simplicity’s sake, [ROBO HUB] designed this replica to use materials readily available around the home. Thanks to its cardboard construction, it’s easy to replicate with a minimum of tools. One need merely cut out the various sections before assembling them together with hot glue, with popsicle sticks serving as the legs. A juice bottle is used as the primary button itself, with aluminium foil serving as the contacts and rubber bands standing in for the spring.

It’s not the most useful button, given that it it’s quite fragile and has a weak spring return. However, it would be a great teaching tool to show students exactly what’s going on inside an actual button. As a bonus, it looks like it would be remarkably fun to pound on to activate some kind of massive air horn. Just an idea.

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