A Simple Yet Feature-Packed Programmable DC Load

February 28, 2020 by Dan Maloney 14 Comments

If you’ve got the hankering to own a lab full of high-end gear but your budget is groaning in protest, rolling your own test equipment can be a great option. Not everything the complete shop needs is appropriate for a DIY version, of course, but a programmable DC load like this one is certainly within reach of most hackers.

This build comes to us courtesy of [Scott M. Baker], who does his usual top-notch job of documenting everything. There’s a longish video below that covers everything from design to testing, while the link above is a more succinct version of events. Either way, you’ll get treated to a good description of the design basics, which is essentially an op-amp controlling the gate of a MOSFET in proportion to the voltage across a current sense resistor. The final circuit adds bells and whistles, primarily in the form of triple MOSFETS and a small DAC to control the set-point. The DAC is driven by a Raspberry Pi, which also supports either an LCD or VFD display, an ADC for reading the voltage across the sense resistor, and a web interface for controlling the load remotely. [Scott]’s testing revealed a few problems, like a small discrepancy in the actual amperage reading caused by the offset voltage of the op-amp. The MOSFETs also got a bit toasty under a full load of 100 W; a larger heatsink allows him to push the load to 200 W without releasing the smoke.

We always enjoy [Dr. Baker]’s projects, particularly for the insight they provide on design decisions. Whether you want to upgrade the controller for a 40-year-old game console or giving a voice to an RC2014, you should check out his stuff.

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Raspberry Pi 4 Offers Up 2 GB For The Price Of One

February 27, 2020 by Tom Nardi 54 Comments

The Raspberry Pi 4 represents a significant performance increase over previous generations, unlocking potential applications that were simply beyond the abilities of these diminutive Single Board Computers (SBCs) in the past. Some would even argue that the Pi 4, with a quad-core Cortex-A72 running at 1.5 GHz, now holds its own as a lightweight ARM desktop computer for those interested in finally breaking free from x86.

In light of the considerable upgrade in processing power, the choice to outfit the base model Pi 4 with just 1 GB of RAM always seemed a bit odd. So it’s little surprise that the Raspberry Pi Foundation has decided to shift things around and lower the price of the 2 GB model to the traditional $35. In a blog post this morning, Eben Upton said that with RAM prices falling over the last year, the company thought it was time they passed the savings onto the customer.

This change comes just two days before the Pi’s 8th birthday. There has been speculation that the Pi 4 is capable of operating with 8 GB of RAM and unveiling that news to coincide with this anniversary would have been a clever marketing move. Alas, it looks like we’ll have to continue to wait.

For those who are invested in the 1 GB model, have no fear. Rather than delete the product from the lineup entirely, the company will be keeping it available for anyone who needs it. So if you’ve got a commercial or industrial application that might not take kindly to the hardware getting switched out, you’ll still have a source of spares. That said, the pricing for the 1 GB model won’t be changing, so there’s no cost advantage to using it in new designs.

Combined with news that compatibility issues the Pi 4 had with generic USB-C power supplies was fixed with an under the radar board revision, it seems there’s never been a better time to upgrade to the latest and greatest version of everyone’s favorite Linux board. Happy Birthday, Raspberry Pi.

Now You Can Be Big Brother Too, With A Raspberry Pi License Plate Reader

February 26, 2020 by Jenny List 60 Comments

If you are wowed by some of the abilities of a Tesla but can’t quite afford one, perhaps you can enhance your current ride with a few upgrades. This was what [Robert Lucian Chiriac] did with his Land Rover, to gain some insight into automotive machine vision he fitted it with a Raspberry Pi and camera with an automatic number plate recognition system.

This bracket should find a use in a few projects.

His exceptionally comprehensive write-up takes us through the entire process, from creating a rather useful set of 3D-printed brackets for a Pi and camera through deciding the combination of artificial intelligence software components required, to making the eventual decision to offload part of the processing to a cloud service through a 4G mobile phone link. In this he used Cortex, a system designed for easy deployment of machine learning models, which he is very impressed with.

The result is a camera in his car that identifies and reads the plates on the vehicles around it. Which in a way has something of the Big Brother about it, but in another way points to a future in which ever more accessible AI applications self-contained without a cloud service become possible that aren’t quite so sinister. It’s an inevitable progression whose privacy questions may go beyond a Hackaday piece, but it’s also a fascinating area of our remit that should be available at our level.

You can see the system in action in the video below the break, as well as find the code in his GitHub repository.

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Raspberry Pi Slips Out New PCB Version With USB C Power Fix

February 23, 2020 by Jenny List 102 Comments

When the Raspberry Pi people release a fresh model in their line of fruity single board computers, it’s always an event of great interest. The Raspberry Pi 4 brought some significant changes to the formula: they moved to ~~mini~~ micro HDMI and USB-C power sockets, for instance. The early adopters who scored one of those Pi 4s were in for a shock though, if they had all but the most basic USB C power cables the device wouldn’t power up. Now the Register has news that they have slipped out with little fanfare an updated version of the board containing a fix for this problem.

Our colleague Maya Posch delved deeply into the USB C specification and delivered a pithy analysis at the time which demonstrated that the fault lay with the configuration of the sense resistors used by intelligent USB C power sources to determine what power to supply. For the addition of a single surface mount resistor the problem need never have existed, and we’re guessing that’s how they fixed it.

There’s no need to despair should you have one of the older boards, though. They will still work as they always have done with the so-called “dumb” power supplies and cables, and meanwhile we’re sure that future Pi boards will have had a lot of attention paid to their USB power circuitry.

Restoring The Coolest Laptop Ever

February 21, 2020 by Dan Maloney 47 Comments

Well-seasoned readers will no doubt remember GRiD laptops, the once and always tacti-cool computers that dominated the military market for decades. GRiDs were the first laptops to go to space, and they were coveted for their sleek (for the time) good looks and reputation as indestructible machines.

The GRiDs went through many iterations, and even though their military roots make them nearly unobtanium, [Simon] scored a GRiD laptop and set about restoring it. His theme was the 1986 movie Aliens, which featured a few GRiD Compass computers as props. [Simon]’s 1550SX came a little later than the Compass 2, but documents with the machine reveal it was a Royal Air Force machine that had been deemed unserviceable for reasons unknown.

[Simon] carefully tore it down – pay close attention to the video below and you’ll hear the telltale plink of the magnesium case parts rather than the dull thud of plastic; they don’t make them like that anymore – and cleaned it up. He replaced the original display with a PiMoroni 10″ retro game display to keep the original 4:3 aspect ratio. A Raspberry Pi 4 went inside, along with a Teensy to take care of adapting the GRiD keyboard to USB and lighting up some front-panel LEDs. A second Teeny allows the original IsoPoint mouse to be used, which is a real gem. With the addition of appropriate graphics, the machine looks like it would be at home on a Colonial Marines dropship.

We love the retro feel of [Simon]’s build, and the movie nostalgia. We’re just glad he didn’t include a LiPo battery, which might not get along with the magnesium case. Game over, man!

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Relive The Glory Days Of Cable TV With This Retro Weather Feed

February 21, 2020 by Dan Maloney 43 Comments

This may surprise younger readers, but there was once a time when the reality programming on The Weather Channel was simply, you know, weather. It used to be no more than a ten-minute wait to “Local on the Eights”, with simple text crawls of local conditions and forecasts that looked like they were taken straight from the National Weather Service feed. Those were the days, and sadly they seem to be gone forever.

Or perhaps not, if this retro weather channel feed has anything to say about it. It’s the product of [probnot] and consists of a simple Python program that runs on a Raspberry Pi. Being from Winnipeg, [probnot] is tapping into Environment Canada for local weather data, but it should be easy enough to modify to use your local weather provider’s API. The screen is full of retro goodness, from the simple color scheme to the blocky white text; the digital clock and local news crawl at the bottom complete the old school experience. It doesn’t appear that the code supports the period-correct smooth jazz saxophone, but that too should be a simple modification.

All jibing aside, this would be a welcome addition to the morning routine. And for the full retro ride, why not consider putting it in an old TV case?

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Insecure Surveillance Cameras Provide Dystopian Peep Show

February 18, 2020 by Kristina Panos 29 Comments

It probably doesn’t surprise you to hear there are tens of thousands of web-connected cameras all over the world that are set to take the default credentials. Actually, there are probably more than that out there, but we can assure you that at least 70,000 or so are only a click away. With this project, [carolinebuttet] proves that it’s quite possible to make art from our rickety, ridiculous surveillance state — and it begins with a peephole perspective.

The peephole in your own front door grants you the inalienable right to police your porch, stoop, or patch of carpet in the apartment building’s hallway while going mostly undetected. In Virtual Peephole, the peephole becomes a voyeuristic virtual view of various corners of the world.

Slide aside the cover, and an LDR connected to an Arduino Micro detects the change in light level. This change makes the Micro send a key press to a Raspberry Pi, which fetches a new camera at random and displays it on a screen inside the box. You can peep a brief demo after the break, followed by a couple of short build/walk-through videos.

If you’re a peephole people watcher, put a camera in there and watch from anywhere.

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