PCB Mods Silence Voltage Warnings On The Pi 4

February 12, 2021 by Tom Nardi 122 Comments

If you’ve ever pushed the needle a bit on your Raspberry Pi, there’s a good chance you’ve been visited by the dreaded lightning bolt icon. When it pops up on the corner of the screen, it’s a warning that the input voltage is dipping into the danger zone. If you see this symbol often, the usual recommendation is to get a higher capacity power supply. But experienced Pi wranglers will know that the board can still be skittish.

Sick of seeing this icon during his MAME sessions, [Majenko] decided to attack the problem directly by taking a close look at the power supply circuitry of the Pi 4. While the official schematics for everyone’s favorite single-board computer are unfortunately incomplete, he was still able to identify a few components that struck him as a bit odd. While we wouldn’t necessarily recommend you rush out and make these same modifications to your own board, the early results are certainly promising.

The first potential culprit [Majenko] found was a 10 ohm resistor on the 5 V line. He figured this part alone would have a greater impact on the system voltage than a dodgy USB cable would. The components aren’t labeled on the Pi’s PCB, but with a little poking of the multimeter he was able to track down the 0402 component and replace it with a tiny piece of wire. He powered up the Pi and ran a few games to test the fix, and while he definitely got fewer low-voltage warnings, there was still the occasional brownout.

Going back to the schematic, he noticed there was a 10 uF capacitor on the same line as the resistor. What if he bumped that up a bit? The USB specifications say that’s the maximum capacitive load for a downstream device, but he reasoned that’s really only a problem for people trying to power the Pi from their computer’s USB port.

Tacking a 470 uF electrolytic capacitor to the existing SMD part might look a little funny, but after the installation, [Majenko] reports there hasn’t been a single low-voltage warning. He wonders if the addition of the larger capacitor might make removing the resistor unnecessary, but since he doesn’t want to mess with a good thing, that determination will be left as an exercise for the reader.

It’s no secret that the Raspberry Pi 4 has been plagued with power issues since release, but a newer board revision released last year helped smooth things out a bit. While most people wouldn’t go this far just to address the occasional edge case, it’s good to know folks are out there experimenting with potential fixes and improvements.

Stepping Down Voltage With Reliability

January 13, 2021 by Bryan Cockfield 36 Comments

The availability of inexpensive electronics modules has opened up a world of opportunity for more complex projects to be completed quickly. Rather than designing everything from scratch, ready-made motor modules, regulators, computer vision modules, and control modules all ready to be put to work after arriving at one’s doorstep. Sometimes, though, these inexpensive electronics aren’t all they’re cracked up to be, so [Jan] decided to produce them from scratch instead.

[Jan] is the creator of several robots, and frequently makes use of 3.3V and 5V step down modules, but was not happy with the consistency offered by the prefab modules. The solution to this was to build them from scratch in a way that makes producing a large amount nearly as easy as ordering them. The boards are based around the SY8105 chip, and are built in two batches for the robotics shop based on the two most commonly needed output voltages. With their design they get exactly what they need every time, without worrying about reliability from a random board shop overseas.

The robotics shop is called RoboticsBrno and they have made the schematics available for anyone that wants to build their own. That being said, the design does not make considerations for low noise since it isn’t required for their use case, but if you’d prefer something simple and reliable this will get the job done. It’s also important to understand the limitations of the parts in a build that are built by a third party, although power supplies are a pretty common area to make improvements on.

FM Radio From Scratch Using An Arduino

December 4, 2020 by Bryan Cockfield 50 Comments

Building radio receivers from scratch is still a popular project since it can be done largely with off-the-shelf discrete components and a wire long enough for the bands that the radio will receive. That’s good enough for AM radio, anyway, but you’ll need to try this DIY FM receiver if you want to listen to something more culturally relevant.

Receiving frequency-modulated radio waves is typically more difficult than their amplitude-modulated cousins because the circuitry necessary to demodulate an FM signal needs a frequency-to-voltage conversion that isn’t necessary with AM. For this build, [hesam.moshiri] uses a TEA5767 FM chip because of its ability to communicate over I2C. He also integrated a 3W amplifier into this build, and everything is controlled by an Arduino including a small LCD screen which displays the current tuned frequency. With the addition of a small 5V power supply, it’s a tidy and compact build as well.

While the FM receiver in this project wasn’t built from scratch like some AM receivers we’ve seen, it’s still an interesting build because of the small size, I2C capability, and also because all of the circuit schematics are available for all of the components in the build. For those reasons, it could be a great gateway project into more complex FM builds.

Continue reading “FM Radio From Scratch Using An Arduino” →

Hackaday Links: October 25, 2020

October 25, 2020 by Dan Maloney 3 Comments

Siglent has been making pretty big inroads into the mid-range test equipment market, with the manufacturers instruments popping up on benches all over the place. Saulius Lukse, of Kurokesu fame, found himself in possession of a Siglent SPD3303X programmable power supply, which looks like a really nice unit, at least from the hardware side. The software it came with didn’t exactly light his fire, though, so Saulius came up with a Python library to control the power supply. The library lets him control pretty much every aspect of the power supply over its Ethernet port. There are still a few functions that don’t quite work, and he’s only tested it with his specific power supply so far, but chances are pretty good that there’s at least some crossover in the command sets for other Siglent instruments. We’re keen to see others pick this up and run with it.

From the “everyone needs a hobby” department, we found this ultra-detailed miniature of an IBM 1401 mainframe system to be completely enthralling. We may have written this up at an earlier point in its development, but it now appears that the model maker, 6502b, is done with the whole set, so it bears another look. The level of detail is eye-popping — the smallest features of every piece of equipment, from the operator’s console to the line printer, is reproduced . Even the three-ring binders with system documentation are there. And don’t get us started about those tape drives, or the wee chair in period-correct Harvest Gold.

Speaking of diversions, have you ever wondered how many people are in space right now? Or how many humans have had the privilege to hitch a ride upstairs? There’s a database for that: the Astronauts Database over on Supercluster. It lists pretty much everything — human and non-human — that has been intentionally launched into space, starting with Yuri Gagarin in 1961 and up to the newest member of the club, Sergey Kud-Sverchkov, who took off got the ISS just last week from his hometown of Baikonur. Everyone and everything is there, including “some tardigrades” that crashed into the Moon. They even included this guy, which makes us wonder why they didn’t include the infamous manhole cover.

And finally, for the machinists out there, if you’ve ever wondered what chatter looks like, wonder no more. Breaking Taps has done an interesting slow-motion analysis of endmill chatter, and the results are a bit unexpected. The footage is really cool — watching the four-flute endmill peel mild steel off and fling the tiny curlicues aside is very satisfying. The value of the high-speed shots is evident when he induces chatter; the spindle, workpiece, vise, and just about everything starts oscillating, resulting in a poor-quality cut and eventually, when pushed beyond its limits, the dramatic end of the endmill’s life. Interesting stuff — reminds us a bit of Ben Krasnow’s up close and personal look at chip formation in his electron microscope.

Bench Supplies Get Smaller Thanks To USB-C

October 19, 2020 by Bryan Cockfield 17 Comments

Bench power supplies are an indispensable tool when prototyping electronics. Being able to set custom voltages and having some sort of current limiting feature are key to making sure that the smoke stays inside all of the parts. Buying a modern bench supply might be a little too expensive though, and converting an ATX power supply can be janky and unreliable. Thanks to the miracle of USB-C, though, you can build your own fully-featured benchtop power supply like [Brian] did without taking up hardly any space, and for only around $12.

USB-C can be used to deliver up to 100W but is limited to a few set voltage levels. For voltages that USB-C doesn’t support, [Brian] turns to an inexpensive ZK-4KX buck-boost DC-DC converter that allows for millivolt-level precision for his supply’s output. Another key aspect of using USB-C is making sure that your power supply can correctly negotiate for the amount of power that it needs. There’s an electronic handshake that goes on over the USB connection, and without it there’s not a useful amount of power that can be delivered. This build includes a small chip for performing this negotiation as well.

With all the electronics taken care of, [Brian] houses all of this in a 3D-printed enclosure complete with a set of banana plugs. While it may not be able to provide the wattage of a modern production unit, for most smaller use cases this would work perfectly. If you already have an ATX supply around, though, you can modify [Brian]’s build using that as the supply and case too.

Continue reading “Bench Supplies Get Smaller Thanks To USB-C” →

USB-C Where It Was Never Intended To Be

July 24, 2020 by Jenny List 25 Comments

The USB-C revolution is well under way, as first your new phone, then your single-board computer, and now your laptop are likely so sport the familiar reversible round-cornered connector. We’re still in the crossover period of requiring to keep micro USB, proprietary laptop, and USB-C power supplies at hand, but the promise of a USB-C-only world is tantalisingly close. For [Purkkaviritys] that’s a little bit closer now, as he’s modified his Thinkpad T440s to take a USB charger instead of its proprietary Lenovo square-plug part. (Video, embedded below.)

At its heart is a USB-PD emulator module that does all the hard work of negotiation with the power supply, giving the laptop the DC voltage it needs. It’s not quite that simple though, because a resistor is required to reassure the laptop that it’s got a genuine power supply. The module is encased in a carefully-designed surround that neatly takes the space vacated by the original connector, and since this laptop has its internal power connector on a short cable it is made very straightforward to fit into the case. If you didn’t know it was a home-made upgrade, you could be forgiven for thinking that this laptop left the factory with a USB-C power socket.

The USB-C module used here is a versatile part. We’ve previously seen it in a soldering iron conversion.

Continue reading “USB-C Where It Was Never Intended To Be” →

A DIY Electronics Lab You Can Show Off With Pride

May 25, 2020 by Tom Nardi 27 Comments

It’s hardly a secret that getting into a serious electronics habit can be detrimental to your bank account. A professional grade lab is simply unobtainable for many a tinkerer, and even mid-range hardware can set you back considerably. Which is why many folks just starting out will attempt to salvage or build as much of their equipment as possible. It might not always be pretty, but it’ll get the job done.

But this project by [Chrismettal] could end up completely reinventing the home electronic workspace. Using 3D printed frames, low-cost components, and a sprinkling of custom PCBs, this modular electronics workbench has all the bells and whistles an aspiring hardware hacker could need. As an added bonus, it looks like something that came off the International Space Station.

Inside the resistor substitution module.

This is one of those projects that simply can’t be done justice in a few paragraphs. If you’ve ever wanted to put together a dedicated electronics workbench but were put off by the cost of individual components, read though the fantastic documentation [Chrismettal] has prepared for the EleLab_v2. Is it all top-of-the-line hardware? No, of course not. But it’s more than suitable for the kind of work people in this community usually find themselves involved in on a weekend.

So what’s included? Naturally [Chrismettal] has created a power supply module, in both variable and fixed flavors. But there’s also a module for a resistor substitution, a component tester, and even a digital storage oscilloscope. You can mix and match the modules suit your needs, and if you want to create entirely new ones, the FreeCAD sources are available to get you started.

We’ve seen low-cost power supply modules before, and naturally we’re no strangers to cheap DSO kits. But this project wraps those devices and gadgets up into a form factor that anyone would be happy to have on their bench. We’re exceptionally interested in seeing new modules developed for the EleLab_v2, and doubt this is the last time you’ll see this impressive project grace these pages.

[Thanks to BrunoC for the tip.]