A small, easy to assemble board that makes use of old wall warts.

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This is another mini project that came about because I needed 5V and/or 3.3V for various projects. It makes use of my old wall warts!

Like many of us, I had a bunch of various wall-warts lying around, but sadly though none of them produced a regulated 5V/3.3V. I had some 78xx regulators around, so I went into KiCad and made a board to make those wall-warts useful! Changing the world by saving old wall warts from the dumpster!

I used one to power my ESP8266. It worked but the linear regulator was unsurprisingly getting a bit warm, especially since I was powering the regular from a 9V wall wart. Not exactly very efficient. I looked into drop-in switching regulator replacements for 78xx linear regulators and found some nice ones made by Murata: the OKI-78SR-5/1.5-W36-C for 5V and the OKI-78SR-3.3/1.5-W36-C for 3.3V. Those regulators make it much more feasible to use with commonly found 9V/12V wall warts to power things such as the ESP8266 that draw a good bit of power.

Switching regulator replacements for 78xx liner regulator offer much better efficiency, but sadly do cost substantially more. The UA7805CKCS, a 5v linear regulator from ti can be had for $.74 in Mouser for a quantity of 1; The OKI-78SR-5/1.5-W36-C a 5v switching regulator is $4.30 on Mouser.

Special notes:

The EasyPWR is designed to be used with wall warts that have center positive barrel plugs.

C1 and C2 are 1206 sized pads that should be populated with appropriate value capacitors if using a linear regulator (read the datasheet for recommend values for your model). With switching regulators such as the two models that I mentioned above, the capacitors can usually be left out.

Using the board with a linear regulator is fine to power a typical microcontroller, some LEDs, etc, but if you need to draw say 1 amp of current and your using a 9V/12V wall wart, using a switching regulator is the way to go.

There is a VIN pin to supply power to the board if you are using other than a wall wart for a power source.

There is some space for a small heatsink, the board is not intended for situations in which alot of heat would be dissapted from the regulator.

KiCad project files for the board.

x-zip-compressed - 28.21 kB - 03/24/2017 at 12:49


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  • 1 × PCB Electronic Components / Misc. Electronic Components
  • 1 × 4-pin .1" header
  • 1 × 2.1mm DC barrel jack
  • 1 × 78XX regulator or a switching drop in replacement for the 78XX

  • Selecting the best parts for the job for the deluxe version

    /dev/null2 days ago 0 comments

    I haven't done a PCB design yet, I'm still working out the exact components that I plan on using. I found out that the datasheet for the 3.3V linear regulator that I have on hand (ua78m33c) specifies a minimum voltage input slightly greater than 5V. I've had no issues myself with feeding 5V into it, but would prefer to not use a component outside of its recommended specs in the finished product.

  • Back to work soon

    /dev/null04/18/2017 at 23:11 0 comments

    Just an FYI, I will be getting back to working on the project again, I've been busy the past two or so weeks with Easter and various outdoor projects that needed to be done before the summer heat kicks in. I hope everybody had a great Easter.

  • Thanks for following/liking

    /dev/null04/04/2017 at 12:13 0 comments

    Looks like I'll be designing the deluxe version after all :). I'll likely start working on it in about two or so weeks. I've been busy with varous other projects lately.

    Again, thanks for the support :)

  • Some possible additions for a possible deluxe version

    /dev/null03/24/2017 at 19:05 0 comments

    So far the little board has served me well in providing power to my various projects. I've been thinking about doing a deluxe version that could include.

    Two voltage rails, 5V and 3V. A switching regulator could be used for for 5V. An LDO could be used for 3.3V and tied to the output of the 5V regulator, which would make it much more efficient vs using the voltage directly off of the wall wart, so heat dissipation is less of an issue.

    A power indicator LED for one or both rails.

    Reverse-polarity input protection

    Reverse polarity protection (probably using a p channel MOSFET)

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