Hand machined mechanical pencils

Inside an IKEA Jansjö LED lamp + making a microscope lamp (18/12/13)

The IKEA Jansjö lamp (IKEA part # 001.696.35) is great as a worklight - it has a very good light quality compared with cheaper LED lamps which are often rather bluish. Here, I'm modifying one of the lamps and its power supply to act as a microscope lamp.

Modifying the lamp

The lens and clear bezel are clipped in place and can be carefully removed. The white plastic reflector is held by a couple of screws which also hold the PCB in place against the metal housing. Some thermal grease is used underneath the PCB to provide good heatsinking.

The LED seems to be a Cree XPE series and is driven by two A735 current regulators in parallel. These are rated at 250mA each, or 500mA total. A datasheet for the regulator is available here.

The flexi tube unscrews from the lamp housing. I cut the tube short and turned a piece of PVC rod to hold both the end of the flexi tube and a standard DC power jack. The outside of the PVC body is the same size as the original microscope bulb holder. To tighten the DC jack, I made a little tool to allow it to be tightened entirely from the outside, since it's impossible to hold the body of the jack.


Next, chopping up the power supply to fit it inside the microscope's base.

X-ray of the power supply

Although I didn't really need to, I took some X-rays of the power supply to see where I could safely cut the casing to get the circuit board out.

Fitting the power supply

After some cutting, hot knife blades, and swearing, I got the circuit board out and cut down the casing to fit inside the microscope. The original mains transformer was removed and replaced with the LED power supply. A metal strap holds it down. I used a piece of ¼" audio lead cable to lead power to the lamp, since it's thick and very flexible.


The final result works great - the light is intense, yet still easy on the eyes when viewing things through the 'scope.