Is This Power Supply Bigger Than A Bread Box? No, It Is One.

[newtonn2] must have had food on his mind when he was deciding to embark on a power supply project. The enclosure is quite different…. it is a Bread Box! Even so, flipped up on end we must say it looks pretty cool. [newtonn2’s] previous power supply had crapped out and he needed a replacement supply ASAP, it was a loaf or death situation for this electronics enthusiast.

Similar to a lot of DIY bench power supplies, this one would also be based on an ATX computer power supply. These are good high-current supplies that output voltage in several convenient amounts and in this case are are all routed to their own spring terminals mounted on the enclosure. Even though those standard voltages might be good enough for most, [newtonn2] is extremely kneady and wanted a fully adjustable output so he designed up an adjustable voltage regulation circuit using an LM350 regulator. A volt meter and an amp meter indicates the power being supplied on the adjustable circuit.

Since his last power supply was toast, [newtonn2] wanted this one to be easily repairable. The ATX power supply inside can be replaced in two minutes because nothing is hard wired. The only connections are the ATX connector and power cord. For cooling, holes were drilled in the side of the enclosure so that fans could be installed. This was the yeast he could do to keep the temperature of the interior components down.

In the end [newtonn2] completed his goal of building a pretty unique and functional bench top power supply without spending a lot of dough. Check out his Instructable for extremely detailed build instructions including schematics for how all his components are wired.

26 thoughts on “Is This Power Supply Bigger Than A Bread Box? No, It Is One.

    1. While this isn’t a bad power supply for basic usage, it isn’t anywhere near “equivalent to a $300 lab supply” – a proper bench supply includes voltage -and- current regulation (with constant current and/or constant voltage), along with over-current cutout, a voltage range down to 0 volts – and for $300.00, you could probably get a dual-output supply as well.

      I sincerely doubt that the builder of this supply considers it “equivalent” – and no one else should, either. There are many benefits to having a proper bench/lab power supply, even if they do cost a bit more than a build like this (though if you shop around for used equipment, lab supplies can be found cheaper). But this supply is better than nothing, and can help the beginner electronics hobbyist out greatly, or work well for quick testing and repair of other devices (where setting up a bench supply might be more of a pain).

      1. Whoah there bro. That’s $300 NZ Dollars, used to buy a priced-way-over-rrp-because-your-country-hates-mine product.

        I wonder if it’s still cheaper for New Zealanders and Australians to fly to America and buy certain products and fly back than it is to buy it here, or whether that has changed slightly or not…

  1. It looks like blobs of silicone are holding the lid on as hinges, these boxes have the door loose to use as a cutting or serving board. I would mention the use of cloth as a hinge in this case, glued on with the same stuff. If cut at a 45 degree angle across the cloth it’s much stronger. A strip an inch wide pressed into the glue. Use wax paper to keep it from sticking to itself at the hinge line.
    A breadbox is a easy choice for the task, sorta like a 3D breadboard. A common thrift store item, as well as other nick-knack boxes.

  2. These days there are lots of cheap Buck mode switcher boards from China that have CV CC (Constant Voltage Constant Current) outputs. The constant current mode can be used as current limits in case you have a short circuit etc. Pair them with a decent quality old laptop power that was huge and still built with quality and that should be fine for most digital projects. Or you can go old school and use a transformer from old electronics in the 80’s. The tranformer would give Earth ground isolation and might be handy at times.

    The cheap ones are around $5 with a couple of multi turn trim pots while there is a B3603 with a 4 digits LED readout, 4 button keypad which is firmware controlled for about $16. Make sure you get ones are are 150kHz or higher switches as they would have lower output ripples. You can probably clean up the output a bit by adding a filter cap and a LC filter.

    At those prices, not even sure why one would not have a few around (instead of a huge one) for projects. Being switches also means that they are efficient, not having a fan and can be stuffed inside a box.

        1. It was a compromise for the large output range and high current (which I tended to use at low voltage).
          If I need even higher current @ low voltage, I got a few Telecom quarter bricks samples (~200W range) for 5V and 12V fixed voltages that I can drive from it.

  3. It is a logical step after the breadboard. Next is PCB etching with baker ingredients, SMD soldering with bread making machines and using breadknifes to… Hang on eine minute… Most of this is common place. My god man, The wheat revolution that was started in the Neolithic is still fueling our technological innovation as we speak..

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