Quick Negative Voltage For An Op Amp

December 14, 2023 by 30 Comments

It is a classic problem when designing with op amps: you need the output to go to zero, but — for most op amps — you can’t quite get down to the supply rail. If your power options are a positive voltage and ground, you can’t get down to zero without a special kind of op amp which might not meet your needs. The best thing to do is provide a negative supply to the chip. Don’t have one? [Peter Demchenko] can help. He uses a simple two-transistor multivibrator along with some diodes and capacitors to generate a minimal negative voltage for this purpose.

The circuit is simple and only produces a small negative voltage. He mentions that into a 910 ohm load, he sees about -0.3V. Not much, but enough to get that op amp down to zero with a reasonable load. Unlike other circuits he’s used in the past, this one is efficient. With a 5-volt input, it draws less than 1.5 mA.

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Disposable Vape Batteries Turned USB Power Bank

December 14, 2023 by 31 Comments

It’s another one of those fun quirks about our increasingly cyberpunk world — instead of cigarette butts littering our streets, you’re more likely to find disposable vaporizers that have run out of juice. Unfortunately, while the relatively harmless paper remnants of a cig would eventually just fall apart when exposed to the elements, these futuristic caltrops are not only potentially explosive thanks to their internal lithium-ion battery but aren’t going anywhere without some human intervention.

So do the environment and your parts bin a favor: pick them up and salvage their internal cells. As [N-Ender_3] shows with this build, it’s cheap and easy to turn the remnants of a few vapes into a useful USB power bank. In this case, the enclosure is 3D printed, which makes it particularly form-fitting, but you could just as easily pack the cells into something else if you’re not a fan of extruded plastic.

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Hacker Tactic: Internal ESD Diode Probing

December 14, 2023 by 15 Comments

Humans are walking high voltage generators, due to all the friction with our surroundings, wide variety of synthetic clothes, and the overall ever-present static charges. Our electronics are sensitive to electrostatic discharge (ESD), and often they’re sensitive in a way most infuriating – causing spurious errors and lockups. Is there a wacky error in your design that will repeat in the next batch, or did you just accidentally zap a GPIO? You wouldn’t know until you meticulously check the design, or maybe it’s possible for you to grab another board.

Thankfully, in modern-day Western climates and with modern tech, you are not likely to encounter ESD-caused problems, but they were way more prominent back in the day. For instance, older hackers will have stories of how FETs were more sensitive, and touching the gate pin mindlessly could kill the FET you’re working with. Now, we’ve fixed this problem, in large part because we have added ESD-protective diodes inside the active components most affected.

These diodes don’t just help against ESD – they’re a general safety measure for protecting IC and transistor pins, and they also might help avoid damaging IC pins if you mix. They also might lead to funny and unexpected results, like parts of your circuit powering when you don’t expect them to! However, there’s an awesome thing that not that many hackers know — they let you debug and repair your circuits in a way you might not have imagined.

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The Nintendo Switch CPU Exposed

December 14, 2023 by 8 Comments

Ever wonder what’s inside a Nintendo Switch? Well, the chip is an Nvidia Tegra X1. However, if you peel back a layer, there are four ARM CPU cores inside — specifically Cortex A57 cores, which take up about two square millimeters of space on the die. The whole cluster, including some cache memory, takes up just over 13 square millimeters. [ClamChowder] takes us inside the Cortex A57 inside the Nintendo Switch in a recent post.

Interestingly, the X1 also has four A53 cores, which are more power efficient, but according to the post, Nintendo doesn’t use them. The 4 GB of DRAM is LPDDR4 memory with a theoretical bandwidth of 25.6 GB/s.

The post details the out-of-order execution and branch prediction used to improve performance. We can’t help but marvel that in our lifetime, we’ve seen computers go from giant, expensive machines to the point where a game console has 8 CPU cores and advanced things like out-of-order execution. Still, [ClamChowder] makes the point that the Switch’s processor is anemic by today’s standards, and can’t even compare with an outdated desktop CPU.

Want to program the ARM in assembly language? We can help you get started. You can even do it on a breadboard, though the LPC1114 is a pretty far cry from what even the Switch is packing under the hood.

How Germany’s Troubled Pebble Bed Reactor Came Of Age In China

December 14, 2023 by 57 Comments

Although the concept of nuclear fission is a simple and straightforward one, the many choices for fuel types, fuel design, reactor configurations, coolant types, neutron moderator or reflector types, etc. make that nuclear fission reactors have blossomed into a wide range of reactor designs, each with their own advantages and disadvantages. The story of the pebble bed reactor (PBR) is among the most interesting here, with its development winding its way from the US Manhattan Project over the Atlantic to Germany’s nuclear power industry during the 1960s, before finding a welcoming home in China’s rapidly growing nuclear power industry.

As a reactor design, PBRs do not use fuel rods like most other nuclear reactors, but rather spherical fuel elements (‘pebbles’) that are inserted at the top of the reactor vessel and extracted at the bottom, allowing for continuous refueling, while helium acts as coolant. With a strong negative temperature coefficient, the design should be extremely safe, while providing high-temperature steam that can be used for applications that otherwise require a coal boiler or gas turbine.

With China recently having put its twin-PBR HTR-PM plant into commercial operation, why is it that it was not the US, Germany or South Africa to first commercialize PBRs, but relative newcomer China?

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Polish Train Manufacturer Threatens Hackers Who Unbricked Their Trains

December 14, 2023 by 63 Comments

A week ago we covered the story of a Polish train manufacturer who was caught using software to brick their products after they had been repaired by in independent railway workshop. Now 404 Media has a follow-up story with more information, including the news that the hackers responsible for the discovery are now being threatened by the manufacturer.

The more we learn about this story the more interesting it becomes, as the Newag trains in question began failing after service as far back as 2021. In desperation after services were affected by the number of non-functional units, an employee searched online for Polish hackers and found a group called Dragon Sector. The group was able to find the issue, and are now being threatened with legal action by the manufacturer, who are citing possible safety issues.

It’s clear from where we are standing that Newag have been caught red-handed in some extremely dubious practices, and seem to have little sense of how their actions might not be the best in terms of protecting their reputation. We are guessing that the European regulators will become very interested in this case, and that meanwhile the order books of a company which puts DRM in its trains will start to look very empty indeed. You can catch our original coverage as the story broke, here.

Thanks [JohnU] for the tip.

When Is A Typewriter A Printer? When It Has A Parallel Port

December 14, 2023 by 13 Comments

If you want to talk to a typewriter using something other than your fingers on the keys, you could do a lot worse than to pick up a specimen featuring a Centronics parallel port. That’s what happened to [mlupo], who came across an old Swintec 1146 CMP and decided to hack it into an art installation.

At the push of a giant, clicky button, the typewriter now spits out family stories. This is all thanks to an Adafruit KB2040 keyboard driver being used in a new, exciting way — as a printer driver.

More specifically, the CircuitPython program running on the KB2040 takes in a text file and then sends the data one character at a time until a newline is reached. At that point, the typewriter sends a busy signal and the characters are typed.

As soon as the typewriter is no longer occupied, the data stream picks back up until the next newline or until the file is completely typed out.

Once [mlupo] figured out enough of the parallel port protocol, they were able to build a custom breakout board with the KB2040, a female parallel port, and a row of LEDs for debugging that [mlupo] kept because they look cool.

The KB2040 sets the values high on a series of the parallel port’s data pins, along with the port’s STROBE pin, which pulls low when data is ready. During each STROBE cycle, the high and low pins are read by the Swintec as a binary character.

Of course, you can always use the power of Pi to build your own modern typewriter.

Thanks to [foamyguy] for the tip!