Tag Archives: hardware

Not Quite 101 Uses For An ATX Power Supply

via hardware – Hackaday

The PC power supply has been a standard of the junk box for the last couple of decades, and will probably continue to be for the foreseeable future. A product that is often built to a very high standard and which will give years of faithful service, yet which has a life of only a few years as the PC of which it is a part becomes obsolete. Over the decades it has evolved from the original PC and AT into ATX, supplying an ever-expanding range of voltage rails at increasing power levels. There have been multiple different revisions of the ATX power supply standard over the years, but they all share the same basic form factor.

So a pile of ATX supplies will probably feature in the lives of quite a few readers. Most of them will probably be old and obsolete versions of little use with today’s motherboards, so there they sit. Not small enough to ignore, yet Too Good To Throw Away. We’re going to take a look at them, try to work out what useful parts they contain, and see a few projects using them. Maybe this will provide some inspiration if you’re one of those readers with a pile of them seeking a purpose.

What’s Inside The Box?

A typical ATX PSU schematic using a TL494. Dianyuan.com forum [Public domain], via Wikimedia Commons.
A typical ATX PSU schematic using a TL494. Dianyuan.com forum [Public domain], via Wikimedia Commons.
ATX power supplies follow a closely defined standard, so it should come as little surprise that many of them share very similar circuitry inside even if they come from different manufacturers. There are a variety of integrated circuits you’ll find running the show whose data sheets will often give you an entire ATX power supply schematic, but since their circuitries will often be very similar we’re showing you one of the most common.

The TL494 is a switched-mode power supply controller designed to work in a variety of configurations and manufactured by multiple semiconductor companies.

The basic operation of a switch-mode power supply is fairly straightforward, and ATX supplies have very few deviations from the norm. There is a mains rectifier and filter, a pair of high-voltage power transistors that switch the resulting DC at a few tens of kHz into a ferrite-cored transformer whose output is rectified to low voltage DC. The TL494 samples the output voltage and produces the PWM switching signal which is fed to the bases or gates of the power transistors through a drive transformer. There will also be a standby 5V supply using another small transformer, and a “power good” circuit to tell the motherboard that the PSU is ready and to activate the supply on an external input.

A typical ATX PSU interior. Alan Liefting (Own work) [Public domain], via Wikimedia Commons.

A typical ATX PSU interior



A: bridge rectifier

B: input filter capacitors, between B and C – Heatsink for HV transistors

C: transformer, between C and D – Heatsink for low-voltage rectifiers

D: output filter coil

E: output filter capacitors


Alan Liefting [PD], via Wikimedia Commons.

These supplies are slightly unusual in the age of surface-mount components, in that the majority of them you’ll find in a junk box still have through-hole construction. This makes them suitable targets for the electronic scavenger, as parts can more easily be retrieved intact. It’s worth taking a moment to look at the components you’ll find, and suggest some uses for them.

Parts, Parts, Parts

Most obvious when dismantling one of these boxes are the metal case, IEC connector, power switch, and fan. You shouldn’t need an explanation of how these could be reused, if you don’t mind a bit of steel drilling and your project case being obviously that of a PC power supply then they are very robust enclosures. The same goes for the wiring loom of motherboard and disk power connectors, a handy source of medium-sized hook-up wire.

If you look at the components on the PCB, many of them are standard discretes. Yes, we’ve all scavenged a 10K resistor at some point, but outside a few high-voltage capacitors in general they are not much to get excited about. So what is there on that board that’s worth lifting?

Just a selection of ATX power supply magnetics and cores.
Just a selection of ATX power supply magnetics and cores.

One thing that’s in abundance on an ATX PSU board are magnetics. Toroidal chokes and ferrite bobbins used in filters as well as the various ferrite cored transformers. The transformers are wound for the specific purpose so unless you have the patience to rewind them they may be of little use, but the chokes have more application. These are not exotic RF ferrites but more utilitarian iron-dust cores, though they still can find plenty of use wherever a choke is required. I’ve even used them as cores for co-ax baluns, when their purpose is simply to stop RF leaking down the feeder their poor RF performance is an asset. It’s also worth noting from an RF perspective that these chokes are also a handy source of plenty of heavy-gauge enamelled copper wire for your other inductors.

The semiconductors in an ATX PSU include some specialist components, but there are still alternative applications for them. On the high voltage side are a selection of high-voltage diodes and those switching transistors, all of which are a fertile source of parts if you are hacking together high voltage inverters. On the low voltage side apart from the TL494 or other controller chip you’ll find some high current rectifiers and more than one three-terminal 78XX series regulator if you are lucky, as well as in many cases a TL431 adjustable voltage reference. You may also find the various heatsinks to be useful in other projects.

Use It, Don’t Break It!

As you can see, an ATX PSU can yield some useful components. But since there is an almost limitless supply of them it’s not worth breaking one unless you need the parts, so what can you do with an intact one?

A bench PSU project we covered back in 2010.
A rather nicely built bench PSU project we covered back in 2010.

The answer is pretty simple: how about using it as a bench power supply? These supplies are not electrically the quietest or best regulated in the world, but they do have the advantage of providing several useful voltage rails at significant current levels. There is a small modification required to use one in this way, one of the lines is an enable line that is held high. Pull pin 16 low (usually a green wire) and the supply will start up. There are numerous projects on Hackaday.io showing how others have done this, and a quick search of OSH Park will yield a range of breakout PCBs like this one.

If fixed voltages aren’t enough, there have been many ATX bench PSU projects like the one pictured fitted with LM317 variable regulators on their 12V lines to provide an adjustable output. That is not the only way that this can be achieved though, the TL494 can be readily made into a variable regulator with a simple modification. The standard warnings and disclaimers apply with respect to the dangers of working on mains and high voltage equipment if you follow that route.

Of course, using a power supply as a power supply is all very useful, but it’s hardly groundbreaking even if it does sometimes involve a bit of hardware hacking. How about other uses for one? One area for which a supply capable of producing large currents might be suited for example is welding. It’s important to point out that by welding we do not mean the kind of welding you’d make ships or even cars out of, but that’s not the only place you’ll find a welder (This spot welder using just the case of an ATX supply is a fine project, but doesn’t quite count in this context). Last year for example we covered an ATX supply being used with a graphite electrode to weld thermocouples, providing a significant savings over commercial alternatives. And the metalworking potential of an ATX supply does not end there, you’ll find people using them for resistance soldering in the model making community.

So, you’ve still got that pile of metal bricks under the bench from all the old PCs that have come your way, but with luck after reading this you’ll have a bit of inspiration that may enable you to do something with them. Whatever you make be sure to share it with us on Hackaday.io, and don’t forget to send us the link!

Filed under: Hackaday Columns, hardware, parts, Skills

RadarCat Gives Computers A Sense of Touch

via hardware – Hackaday

So far, humans have had the edge in the ability to identify objects by touch. but not for long. Using Google’s Project Soli, a miniature radar that detects the subtlest of gesture inputs, the [St. Andrews Computer Human Interaction group (SACHI)] at the University of St. Andrews have developed a new platform, named RadarCat, that uses the chip to identify materials, as if by touch.

Realizing that different materials return unique radar signals to the chip, the [SACHI] team combined it with their recognition software and machine learning processes that enables RadarCat to identify a range of materials with accuracy in real time! It can also display additional information about the object, such as nutritional information in the case of food, or product information for consumer electronics. The video displays how RadarCat has already learned an impressive range of materials, and even specific body parts. Can Skynet be far behind?

Again, this could provide robots with a sense of touch, in a manner of speaking, that rivals our own human capacity for object recognition. This has applications for a wide range of robots: industrial machines will be able to recognize the material composition of an object that may require more force to lift while wearable versions would assist humans with disabilities. This is a technology worth keeping an eye on.

While this tech is a ways away from widespread use, you can still turn anything into a touch sensor today with Touché.

[via /r/linux]

Filed under: hardware, Software Development

Using The FCC EAS For Fun And Profit

via hardware – Hackaday

When a consumer electronics device is sold in the US, especially if it has a wireless aspect, it must be tested for compliance with FCC regulations and the test results filed with the FCC (see preparing your product for FCC testing). These documents are then made available online for all to see in the Office of Engineering and Technology (OET) Laboratory Equipment Authorization System (EAS). In fact, it’s this publishing in this and other FCC databases that has led to many leaks about new product releases, some of which we’ve covered, and others we’ve been privileged enough to know about before the filings but whose breaking was forced when the documents were filed, like the Raspberry Pi 3. It turns out that there are a lot of useful things that can be accomplished by poring over FCC filings, and we’ll explore some of them.

The first thing to know is how to get to the EAS tool. If you search, you need to search for FCC OET EAS (as FCC EAS is the Emergency Alert System. Thank you FCC for all your helpful TLAs). Or just head directly to the FCC OET EAS. Now that you’re there, you’ll see lots of search fields. The first four rows are probably all you ever need. Every company that registers with the FCC will get a grantee code, which is a unique 3 or 5 digit code that represents the company. Any product they register gets its own product code. Simple enough.

ps4-controller-fcc-idIf you don’t know either (any product that you’re holding in your hand that has an FCC ID is required to put it on the packaging and on the device and in the user manual), just enter in the name of the company in the applicant name and you’ll likely find what you are seeking. The date range is helpful for limiting the results, but also enables another fun option. Just enter today’s date in the from-to fields and you’ll have a list of all the paperwork filed today. This is how the leaks happen. As soon as it’s listed, helpful people will see it and report it.

For fun, let’s look up something that’s near and dear to us; the Raspberry Pi 3. Search for Raspberry Pi in the applicant name and there are a few entries, some dated from 2016, and some from 2014. The 2016 ones are clearly the Pi 3, and their only difference appears to be the frequency range; it’s unclear why there are three separate filings.

Image from Raspberry Pi 3 FCC Filing.
Image from Raspberry Pi 3 FCC Filing.

On any of them, we can look at the detailed information of the filing. This gives us all kinds of goodies, including the external and internal photos, user manual, and testing data. The photos are extremely important for finding motivation, as they will include pictures underneath shields for wireless modules. This lets you look at a product and determine exactly what is inside, which technologies they used, how they laid out the components, etc., and it’s all free and easily available as soon as it’s filed, which is usually before the product is even available for sale. Is there a product you like and you want to find out how they did it? Check the FCC database. Want to do a teardown of some competition without buying their product? Here it is!

Guts of Nest, filed with FCC 8/14/2015
Guts of Nest, filed with FCC 8/14/2015

The Raspberry Pi results aren’t a great example for this because you can already see what’s on the circuit board, so search instead for something like Fitbit or Nest. The internal photos document for the Nest device is 10 pages of detailed images of everything inside! This is very much a wealth of information for learning how the pros do product development. Some companies will obscure the chip labels in the photos, making it a little more difficult to figure out what’s inside.

Probably the least exciting but still useful thing is the test report itself. This is probably 90% boilerplate that is identical in every product, but it will tell you which frequencies it uses, and give you an idea of how strongly it outputs signals. That’s about it. Go back to the photos and user manual for all the good stuff.

Want to learn radio design? Here's a schematic for one that passed FCC approval.
Want to learn radio design? Here’s a schematic for one that passed FCC approval.

Every FCC filing contains a lot of documents, and it’s possible to request permanent confidentiality on some of them. This means that you submit the documents, ask that some of them stay confidential, and those will not be listed on the web site. Some of the documents can’t be confidential, like the user manual, test report, and internal and external photos, but others can, like the Block Diagram, Operation Description, Parts List (BOM), and Schematics. Not everyone files this confidentiality request, so sometimes, if you’re very lucky, you can get a lot more information about a product than you thought possible. For example, do a search for Grantee ZP5 and Product Code BF-82. They didn’t file the confidentiality letter for this particular product (but they did for others), so you can see everything, including schematics showing the part numbers!

If you are preparing your own product for FCC testing, find a couple products you like and see what they did for their documents so you can save yourself some time preparing similar documents. There’s no reason not to! If you want to learn how a particular design challenge was solved, or get the inside scoop on hardware before the release date, FCC EAS is a great place to begin.

[main image source, iPhone 6s FCC ID BCG‑E2946A]

Filed under: Engineering, Featured, hardware

A Completely Open Microcontroller

via hardware – Hackaday

An annotated mRISCV die image

I don’t know about you, but the idea of an Arduino-class microprocessor board which uses completely open silicon is a pretty attractive prospect to us. That’s exactly [onchipUIS]’s stated goal. They’re part of a research group at the Universidad Industrial de Santander and have designed and taped out a Cortex M0 RISCV implementation.

The RISCV project has developed an open ISA (instruction set architecture) for modern 32-bit CPUs. More than 40 research groups and companies have now jumped on the project and are putting implementations together.

[onchipUIS] is one such project. And their twitter timeline shows the rapid progress they’ve been making recently.

Die directly bonded to an OSHPark PCB

After tapeout, they started experimenting with their new wirebonding machine. Wirebonding, particularly manual bonding, on a novel platform is a process fraught with problems. Not only have [onchipUIS] successfully bonded their chip, but they’ve done so using a chip on board process where the die is directly bonded to a PCB. They used OSHPark boards and described the process on Twitter.

The board they’ve built breaks out all the chip’s peripherals, and is a convenient test setup to help them validate the platform. Check it, and some high resolution die images, out below. They’re also sending us a die to image using our electron microscope down at hackerfarm, and we look forward to the results!

The current mRISCV board

Filed under: hardware, Microcontrollers

Wireless Trivia Game Buzzers Using HopeRF RFM69

via hardware – Hackaday

TV game shows follow a formula that hasn’t changed much in sixty years. The celebrity presenter, the glamorous assistant, the catch phrases, the gaudy plywood sets, the nervous contestants, and of course the buzzers.

If you want to do a trivia quiz of your own it’s easy enough to dispense with presenter, assistant, set, and catch phrase, but as well as the contestants you’ll still need the buzzers. You can make a mess of wires that the TV technicians of old would have concealed within that set, but in your home or at the pub that could rapidly become inconvenient.

[Larry] solved his trivia game buzzer problems by building a wireless buzzer set. It features 3D printed enclosures containing Adafruit Feather microcontrollers, and instead of wires it uses RFM69 900MHz radio modules. The master unit displays the quickest contestant on an OLED screen, it features a low power standby mode between button presses to save battery power, and care has been taken to add a random timing to button presses to try to avoid collisions.

The buttons themselves started with a 3D printed button working a single tactile switch, but moved to a set of three switches in a triangle after edge presses failed to activate the single switch.

We’ve featured a wired game show buzzer before, but for the complete game show experience how about this countdown timer?

Filed under: hardware

Hackaday Prize Entry: Vendotron

via hardware – Hackaday

A recurring idea in hackspaces worldwide seems to be that of the vending machine for parts. Need An Arduino, an ESP8266, or a motor controller? No problem, just buy one from the machine!

Most such machines are surplus from the food and drink vending industry, so it’s not unusual to be able to buy an Arduino from a machine emblazoned with the logo of a popular chocolate bar. These machines can, however, be expensive to buy second-hand, and will normally require some work to bring into operation.

A vending machine is not inherently a complex machine nor is it difficult to build when you have the resources of a hackspace behind you. [Mike Machado] is doing just that, building the Vendotron, a carousel vending machine constructed from laser cut plywood and MDF. The whole thing is controlled by an Arduino, with the carousel belt-driven from a stepper motor.

It’s not doing anything commercial vending machines haven’t been doing for years, except maybe having a software interface that allows phone and Bitcoin payments. Where this project scores though is in showing that a vending machine need not be expensive or difficult to build, and broadening access to them for any hackspace that wants one.

We’ve had a few vending machines here before, like this feature on the prototyping process for commercial machines, or even this one that Tweets. Sadly few have a secret button to deliver a free soda though.

Filed under: hardware