Dummy batteries let you use an AC adapter

dummy-batteries-work-as-AC-adapter

We find it frustrating when battery operated consumer electronics don’t include a way to connect an external power supply. We try not to purchase disposable alkaline cells if we can avoid it, and this dummy battery AC adapter hack will aid in our mission.

The battery compartment shown above is for a motorized baby swing. It accepts C sized batteries (who has those just lying around?) and lacks a barrel jack to connect a wall wart adapter. [Jason Smith] mentions you can get around this by connecting your positive and ground wires directly to the conductor springs. But using a dummy battery makes it a bit easier to remove the adapter if you do want to use battery power.

Each of the orange dummy is a wooden dowel with a screw at each end. The screws are connected with a piece of jumper wire, shorting the two terminals. This completes the circuit in the battery compartment and allows him to power everything from the adapter cell at the bottom. The adapter uses an LM317 adjustable voltage linear regulator. He used fixed resistor values to dial in his target voltage. The equipment should be rather forgiving as battery voltage starts higher than the printed value and drops as the cells are used up.

This technique has been around for a long time. One of our favorites was a hack that converted an Apple Magic Trackpad to USB power.

[Read more...]

Wall wart computer mouse

SAMSUNG

This rather bulky looking wall wart is actually a computer mouse. Sure, it may cause your hand to cramp horribly if used for any length of time. But some would say it’s worth that for the hipster value of the thing.

The rather odd shape is somewhat explained by the fact that this was sourced from Ikea. After gutting the transformer found inside the plastic case he had plenty of room to work with. He drilled a hole so that the sensor from a Logitech USB optical mouse can pick up the movement of the mouse. He also got pretty creative when it came to the buttons. The two prongs of the wall plug pivot horizontally to affect the momentary press switches inside.

After the break you can see a quick demo of the project. [Alec] doesn’t consider it to be complete. He wants to make a couple of improvements which include adding weight to make it feel more like the original wall wart, and finding a way to hide the hole he drilled for the sensor.

[Read more...]

Wall-wart retrofitted with a high-power LED supply circuit

high-power-LED-wall-wart-supply

This custom circuit board picks up some of the pieces from a wall wart to drive a high-power LED.  The basic concept is to keep the high-voltage components and swap out the low voltage ones for parts that will be able to drive the 10W load.

The PCB is custom designed, but you can see that it was shaped to match the wall wort’s original board. To the right is the original 500mA transformer. The low-voltage side uses an LM393 because of its dual-comparators. This provides feedback for both current and voltage and is a perfect compliment for the TOP242. We haven’t seen that part before, but [Mincior] says that it’s nice for this application as it has safety features that lock down the chip if power or temperature are above spec. Once the replacement is nestled inside of the plastic case it looks stock and makes sure that your custom LED fixtures will stand the test of time safely.

Everything You Need to Know About Wall Warts

If you work with electronics at any skill level you need juice. [Jon] has a great, and clearly worded tutorial about Wall Wart Power Supplies with pretty much everything you need to know about those little black boxes hanging off of your outlets.

The whole thing starts off with the basics like transformers, rectification smoothing and regulation, then moves on to the different basic types, dedicating a page to linear, regulated and switching types, giving output performance charts under different situations.

Also included is a run-down of DC barrel jack structure so you get the right plug every time, wall wart type identification, a random sample comparison test, and a good selection of formulas to even keep the old hats reading along. Although you might want to set aside a little time at 9 pages and some Q/A in the comments, it might take a moment to read.

SheevaPlug, tiny linux server

plugserv

This little wall plug is actually a full computer with 1.2GHz cpu, with 512MB of RAM and 512MB of of flash memory. It comes with versions of linux, ported for its ARM processor. At $50, this cool system could be finding itself in a lot of homes. You can get more information from the manufacturer. What uses can you think of for it?

[thanks, everyone who sent this in]

Follow

Get every new post delivered to your Inbox.

Join 97,541 other followers