Hackaday Prize Entry: A Better Bench Power Supply

Back in February, [The Big One] started building the bench power supply to rule them all. His previous power supply was just an ATX computer power supply. It worked, but that didn’t give him fancy stuff like different channels of individually adjustable voltages. Since then, we’ve spun up the 2015 Hackaday Prize, and [The Big One] has changed his DIY power supply into a Hackaday Prize entry that competes well against $1000 mid-range commercial units.

The single most expensive component in this power supply are a pair of isolated switched power supplies rated for 15V and 7A. This is a change from [The Big One]’s original plan to use a big ‘ol transformer; a switched mode supply is smaller, lighter, costs about the same, and is much better suited to the modular nature of the project.

The final design for this power supply has some interesting features: up to six channels are possible, voltage and current can go all the way down to zero, and everything can be controlled over USB. Those are amazing features that won’t be found in any $100 cheapo bench power supply, and [The Big One]’s amazing documentation for this project makes it a perfect entry for The Hackaday Prize.

The 2015 Hackaday Prize is sponsored by:

The Modular Bench Power Supply To Rule Them All

Right now, [The Big One] is using an ATX power supply as a bench power supply for all his electronics projects. It works, but it’s not ideal. The next step up from a power supply from an old computer is, in order, one of those Chinese deals on Amazon, a used HP supply, or for the very cool people among us, building your own. [The Big One] is very, very cool and he’s building the modular bench supply to rule them all.

This is not your $100 china special power supply that [The Big One] would have to buy again in a few months. Inside this massive power supply is a massive transformer and rectifier that fans out to multiple power supply modules. The modules themselves will be based on an OPA548 that will be able to supply up to 3A with current limiting.

Each of these channels will be controlled by an ATMega32u4, with all the fancy stuff you’d expect from the ultimate supply; USB for setting voltage, current, and logging data, a nice LCD character display, and it’s surprisingly cheap; just about $100 for the transformer, and about $50 for each module.

It’s shaping up to be a great build, and with all the features, a power supply that would also make a great kit. If you have any input you’d like [The Big One] to hear, let him know on the project page.

Hackaday Links: August 12, 2012

License plate tablet rack

[Hunter Davis] used an old license plate as a tablet stand. It loops around the leg of his laptop table and has a cutout for the power cord of the tablet.

More power power wheels

It may look stock, but this power wheels is hiding a new frame, motors, and tires. You won’t see it in the Power Wheels Racing Series, but it is a ton of fun for this lucky kid.

Surveillance camera chess

Want to play a game? A yellow briefcase hijacks surveillance camera feeds and lets those monitoring them play chess via text message.

ATX bench supply looks like a bench supply

Here’s another rendition of an ATX bench supply. [Ast] rolled in a voltmeter for the variable voltage plug, and an ammeter to finish off the hack.

Lync auto-responder to fool the bossman

In a move reminiscent of [Ferris Bueller], [Sepehr] coded a Lync auto responder to answer the boss when he sends an IM.

Giving an ATX bench supply the case it deserves

Your bench supply doesn’t need to look sad just because you’re using an ATX power supply instead of a commercial product. Follow [Ian Lee’s] example and you could have beautiful wooden enclosures for the tools in your own shop.

The woodworking skills used here aren’t all that advanced, but you need to have a knack for it so we suggest running some test pieces before you start the actual build. [Ian] ran a dado for the front and back panel in each piece of the wood sides. At each corner the inside of the the pieces were mitered at 45 degrees. To put it all together he laid the pieces end to end on a the work bench, then applied painters tape to the outside of the joints. This holds the joints together so that he can flip the collection over, apply glue, and then start hinging the sides into place. It’s almost like rolling up a box.

As with other ATX supply projects we’ve seen [Ian] designed this so that the PSU can be swapped out later if necessary. Instead of wiring his own cable harness he used an ATX breakout board. To get the interface layout he wanted he mounted the banana jacks separately and just ran jumper cables back to that board.

Bench supply built in a power strip

Back in his college days [Print_Screen] grew tired of always building a power supply on his breadboard. To make prototyping quicker he came up with the bench supply that is build into a power strip. This one is using linear regulators for power, and create much less noise on the lines than a supply made from a switch-mode PSU.

First thing’s first, he needed to step down from mains voltage and rectify the AC into DC. He gutted the smallest adapter he could find and managed to fit it into the gutted power strip. It puts out 15V which will work perfectly for the regulators he’s chosen. Each one gets its own slot where an outlet is on the case. The ground hole has been plugged by a toggle switch which routes power to the free-formed regulator/capacitors/heat sink modules. There is a slot for 15V (coming directly off of the converter), 10V, 5V, 3.3V, and two variable regulators which are controlled by the knobs above the outlet. We’ve never seen anything like this and find it most excellent!

[Thanks OverFlow636 via Reddit]

Building a bench supply without altering the ATX psu

[FozzTexx] has been using a bench supply he made from an AT PSU for years. He put a lot of work into that one, removing unnecessary wires, mounting banana plug jacks on the metal case, and adding an on/off switch and labels. But if it ever dies on him it will be a major pain to do all that work again in order to replace it. When he set out to build another bench supply from an ATX PSU he decided to do so without altering the PSU. This way he can easily swap it out for a different one if he ever needs to.

The hardest part of the hack was sourcing connectors. But with the parts in hand he’s able to just plug the faceplate into the stock connector. This gives him access to all of the voltages, and provides an on/off switch and indicator light. He might also want to add the option of resetting the unit if the over-current protection kicks in.

Quieting an inexpensive bench power supply

[Mike] just purchased this Atten APS3005S bench power supply for around $80. It does the job, but boy is it noisy! We were pretty surprised to hear it fire up in the video after the break. To make matters worse, the noise is persistent since the fan never shuts off. Having worked with other bench supplies he knew that a common feature included in many models is temperature controlled case fans. He set out to quiet the fan and implement a temperature switch.

For this project [Mike] had the benefit of looking at a nearly identical model that does have temperature switching. He discovered that the board on this one has a through-hole zero ohm resistor populated in place of a thermostat switch. That switch closes the connection at or above 45 degree Celsius, thereby turning on the cooling fan. Bridging the traces with a zero ohm resistor to save on production costs is what caused the fan to run continuously. After replacing the resistor with a KSD-01F and swapping out the stock fan for a high-quality version [Mike] has takes a noise maker and turned it into a device that’s kind to the ears.

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