How any would it be to have nice reading light at the garden house (or in the car), especially, a light without any smoke and hazard and hazzle like candle light! A light that keeps your eyes healthy. Well, at home, you can just use an IKEA Jansjö light for this purpose, which has a single 3 W LED installed.

All that is needed is a 12 V constant current board, LED driver. These are really cheap, so there is no need to build one yourself, you can just get it shipped from China directly, for a very reasonable price.

This board has a few nice components: 5 SS14 diodes (Schottky), 4 are used a bridge rectifier, 1 is used for the buck converter. There is a 47 Microhenry inductor, a 220 Mikrofarad (25 V) capacitor – and, the magic switch and regulator, a PT4115 device.

The PT4115 features a pretty straightforward design. It’s a step-down converter, can can drive over 1 Amp of current. The board I am using has a 0.22 Ohms current sense resistor, i.e., it is set to 0.1 V/0.22 Ohms = 0.46 A of current. This is plenty to drive the IKEA lamp.

The lamp itself will remain completely unmodified, just using a socket to connect to the original plug (which used to plug into a mains-powered LED driver of similar current rating). The connection to the 12 V system of the garden house is done via a “cigarette lighter” plug.

To protect the driver board, all sealed up in hot glue! It’s not perfect, but it works!

Finally, not much more to say, it works just fine!