More Lights for your Presents


Lights on the tree? Check. Presents under the tree? Check. Lights in the presents? Why not! If your gifts don’t look festive enough and you have a spare inductive charging system lying around the house—though, you could always build your own from scratch—you can brighten things up by installing a few LEDs in the packaging.

The Instructable takes advantage of those new-fangled LED Christmas lights, one strand of which typically draws under 1A and requires around 5V, putting it in the ballpark for popular induction systems used to charge cell phones such as the Powermat. In this particular example, the strand ran off 3 AA batteries, or 4.5V, which meant stepping down the voltage either with a power regulator or, more conveniently, a simple diode in series.

Some additional modifications to the packaging tidy up the installation, including carving out some of the cardboard to recess the receiver and securing everything with hot glue before wrapping it all in paper. You can see a quick demonstration video below.

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Prototyping an advanced inductive charger

This is an advanced inductive charging system into which [David McIntosh] has put a lot of hard work. It uses the same coil-based concepts that we’ve seen in other DIY systems, but the game changer is a communications function that just isn’t found in home brew versions of the hardware. It lets the receiver (device being charged) give feedback to the transmitter by rolling another signal into the EM field being generated.

Do why would you need feedback? Well, if the two coils are not positioned well, the power produced on the receiving end can vary greatly. For instance, you may have the wrong voltage because the coils are not balanced. Or there may not be enough current to properly start charging. The feedback system is designed to let the sending unit change frequency to try to account for physical orientation, or to shut itself off if the charge is just not possible. This is done in expensive commercial devices, and that’s what [David] used as his model.