Converting an Ikea desk lamp to an Altoids Solar light

Ikea makes a wonderful work light (JANSJÖ) that sells for about $13. I have several of them, and love the warm pool of light they provide on desk surfaces. The LED lamp is powered by a small “wall wart,” and only consumes about 3 watts of power.

JANSJÖ Lamp Power Supply

Recently however, one of these lights failed. The power supply and lamp connect with a custom plug and jack system, and by substituting different lamps and power supplies, I was able to find the culprit. A dead power supply. Not a big loss, but what to do with the lamp part that was still good?

After some thought, I realized that the low-wattage lamp could be powered by the solar power supply I use for my amateur radio setup. Measuring a good lamp supply, I discovered it provides 4 volts @ 750 milliamps. The solar supply provides between 12.2 and 13.8 volts, so some voltage conversion was needed. Fortunately, small, inexpensive regulators are available in a variety of  voltages and wattages. They can be found on both eBay and Amazon, and many can use any voltage input from 3 to 35 volts to produce any voltage output from 3 to 35 volts.

I bought one of these supplies earlier to experiment with, and thought it might just do the trick. It was rated at 3 amps maximum output current — plenty for my 750 milliamp needs. One other important detail on this type of DC-DC converter: the input voltage must be at least 1.5 volts higher than the output voltage.  Ample capacity for my project as well. I used alligator clips to test the setup (being careful to set the output voltage well below 4 volts before connecting the lamp) and was able to adjust the supply output to exactly 4 volts. Also, varying the input voltage had no effect on the 4-volt output. Rock solid.

It’s worth mentioning that there are at least two versions of the Ikea JANSJÖ work light. The model I’ve described uses a 4-volt supply, but there is also a 7-volt version. Both will work with this power supply by simply adjusting the output voltage.

Altoids tin with DC buck power supply

Now I needed a way to package everything. I’m fond of Altoids so the answer was easy; just use one of the empty metal containers! The power supply is so tiny that it fits easily in the tin, and I could attach the tin to the underside of my operating desk with some adhesive-backed magnetic strip. There would be room for other Altoids-enclosed projects in the future.

A 5.5 mm x 2.1 mm coaxial power jack was mounted in one end of the Altoids tin, and I disassembled the defective power supply to retrieve the custom jack. It was mounted on the other side. Small nuts and bolts mounted the power supply to the bottom of the tin.

12 Volt power distribution with Altoids supply on mag strip

I had never really made sense of the 12-volt wiring at my operating desk, so this was a great time to install an Anderson Powerpole-style distribution box as well. The solar supply powers two radios and  this new lamp, leaving 6 connectors for future expansion. A cable with an Anderson Powerpole connector on one end and a coaxial plug on the other was also needed.

Now, I really am equipped for emergency operations during a power outage. Hard to operate at night with no light!

The modified Ikea LED lamp