MOSFETs — The Hidden Gate

How many terminals does a MOSFET have? Trick question since most have three leads, even though there are really four connections to the underlying device. It isn’t a conspiracy, though and [Aaron Lanterman] talks about how MOSFETs really work and why thinking of them as three-terminal devices can lead you astray in a recent video that you can watch below.

Like many people, [Aaron] points out the parallel between a triode vacuum tube and a MOSFET. That’s not surprising, since a solid-state tube was exactly what they were looking for when they developed the FET. Since tubes and FETs are both voltage controllers, it is easy to think of the gate as the grid, the source as the cathode, and the drain as the plate. But, [Aaron] shows this isn’t really a very accurate picture.

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Watch Those 1% Resistors

Decades ago, electronic components were not as easy to acquire as they are today. Sure, you could get some things at Radio Shack. But you might not have many choices, and the price would be on the high side. TV repair components were another option, but, again, big bucks. Some places sold surplus parts, which could be cheap. These often came from manufacturing runs where a company bought 10,000 components and made 8,000 products. But today, you can order parts inexpensively and get them on your doorstep in a day or, sometimes, even less. Are these inexpensive parts really any good? [Denki Otaku] likes to find out. In a recent video, he checks out some Amazon-supplied 1% resistors to find out how good they are. You can watch his results below.

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3D Printed Tool Lets You Measure Component Reels Easily

Component reels are a highly-0ptimized packaging format. They deliver components to pick and place machines for effective high-speed assembly. As more of us get into working with SMD components, we’re exposed to them as well. [MG] wanted a way to easily measure tape from component reels, which is difficult because they’re often curled up. Thus, they whipped up a nifty little tool for the job.

The device consists of a 3D printed bracket which is designed to fit on a cheap electronic tape measure from Amazon. The bracket holds an 8mm wide component tape against the measuring wheel. As the component tape is fed through the device, it turns the wheel, and the measurement appears on the screen. No more must you try and flatten out a tape and measure it section by section. Instead, you just feed it in, yank it through, and you’re done!

[MG] notes that the tape measure itself runs on an STM32 microcontroller. As an extra-credit assignment, they suggest that the device could be reprogrammed to display component count instead of distance¬†if that’s more suitable for your application. If you happen to make that mod, be sure to notify us on the tipline!

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Hackaday Links: September 25, 2022

Looks like there’s trouble out at L2, where the James Webb Space Telescope suffered a mechanical anomaly back in August. The issue, which was just announced this week, involves only one of the six imaging instruments at the heart of the space observatory, known as MIRI, the Mid-Infrared Instrument. MIRI is the instrument on Webb that needs the coldest temperatures to work correctly, down to six Kelvins — we’ve talked about the cryocooler needed to do this in some detail. The problem has to do with unexpectedly high friction during the rotation of a wheel holding different diffraction gratings. These gratings are rotated into the optical path for different measurements, but apparently the motor started drawing excessive current during its move, and was shut down. NASA says that this only affects one of the four observation modes of MIRI, and the rest of the instruments are just fine at this time. So they’ve got some troubleshooting to do before Webb returns to a full program of scientific observations.

There’s an old saying that, “To err is human, but to really screw things up takes a computer.” But in Russia, to really screw things up it takes a computer and a human with a really poor grasp on just how delicately balanced most infrastructure systems are. The story comes from Moscow, where someone allegedly spoofed a massive number of fake orders for taxi rides (story in Russian, Google Translate works pretty well) through the aggregator Yandex.Taxi on the morning of September 1. The taxi drivers all dutifully converged on the designated spot, but instead of finding their fares, they just found a bunch of other taxis milling about and mucking up traffic. Yandex reports it has already added protection against such attacks to its algorithm, so there’s that at least. It’s all fun and games until someone causes a traffic jam.

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Let Slip The Chips Of War

We’re going to go out on a limb and predict that future history books will note that the decision to invade a sovereign nation straight after a worldwide pandemic wasn’t exactly the best timing. Turns out the global electronics shortage the pandemic helped to catalyze isn’t just affecting those of us with peaceful intentions, as the Russian war machine is having a few supply issues with the parts needed to build modern weapons and their associated control equipment.

As you might expect, many of these parts are electronic in nature, and in some cases they come from the same suppliers folks like us use daily. This article from POLITICO includes an embedded spreadsheet, broken down by urgency, complete with part numbers, manufacturers, and even the price Moscow expects to pay!

Chips from US-based firms such as Texas Instruments are particularly hard for the Kremlin to source.

So what parts are we talking about anyway? The cheapest chip on the top priority list is the Marvell ‘Alaska’ 88E1322 which is a dual Gigabit Ethernet PHY costing a mere $7.10 USD according to Moscow. The most expensive is the 10M04DCF256I7G, which is an Altera (now Intel) Max-10 series FPGA, at $1,101 USD (or 66,815 Rubles, for those keeping score).

But it’s not just chips that are troubling them, mil-spec D-sub connectors by Airborn are unobtainable, as are all classes of basic passive parts, resistors, diodes, discrete transistors. Capacitors are especially problematic (aren’t they always). A whole slew of Analog Devices chips, as well as many from Maxim, Micrel and others. Even tiny logic chips from Nexperia.

Of course, part of this is by design. Tightened sanctions prevent Russia from purchasing many of these parts directly, which is intended to make continued aggression as economically unpleasant as possible. But as the POLITICO article points out, it’s difficult to prevent¬†some intermediaries from ‘helping out’ without the West knowing. After all, once a part hits the general market, it is next to impossible to guarantee where it will eventually get soldered down.

Thanks to [Kim Tae] for the tip!

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Hackaday Links: April 3, 2022

It’s that time of year again — the 2022 Hackaday Prize has officially launched, and we’re excited to see what it turns out. This year’s theme is “Sustainability, Resilience, and Circularity,” and just in time, too; if the last couple of years has taught us anything, it’s that we’ve got a lot of failure points built into the systems that run our world. As broken as things are, it’s tempting to just curl up in a ball and pretend everything’s fine, but that’s not how hackers respond to adversity. We need to control what we can control, and there’s plenty of work to be done. From sustainable energy ideas to ways to reduce the amount of stuff we throw away, from breathing new life into old equipment to building communities that can take care of themselves, there’s plenty of work to be done. So get over to the Hackaday Prize page, check out the launch summit video if you need some inspiration, and get hacking. And hurry up — things are only going to get better if people like us make it happen.

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Tape Cutter Makes Short Work Of Through-Hole Resistor Reels

As the world of electronics makes its inexorable movement from through-hole parts to surface-mount, it’s easy to forget about the humble wire-ended resistor. But a stack of them is still a very useful resource for any experimenter, and most of us probably have a bunch of them with their accompanying twin strips of tape. We’re entranced by [Sandeep]’s automated resistor tape cutting machine, which uses a fearsome looking pair of motorized knives to slice the tape into predetermined lengths.

At its heart is an Arduino and a set of stepper drivers, and it uses a PCB that he’s designed as a multipurpose board for motor-based projects. One motor advances the reel of resistors, while the other two operate those knives that simultaneously slice the two tapes. The whole is held in a wooden frame with 3D-printed parts, and control is through a touch screen. This feels more like an industrial machine than a maker project, and as can be seen in the video below, it makes short work of those tapes. Full details can be found on his website, including code.

We’ve not had so many through hole tape cutters, but we’ve seen at least one SMD cutter.

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