IKEA Yellow House Nightlight Power Supply

This item was brought to my attention by an old friend who had one of these for his son. This small light emits a soft yellow glow at night and is controlled manually by a switch on the underside.

The batteries are 2 x AA and these power a single coil boost circuit which when tested without a load create around 12 volts. The small current produced means you can connect an LED directly to this clipping the voltage down to around 4volts.

The main problem with this circuit is power consumption. My friend informed me he was changing the batteries around every 10 days.

I redesigned the circuit to override this circuit and instead use a single AA dual coil booster.

Once apart the switch could be reused to power the device and a simple link wire placed across the battery holder to convert the unit to a single battery.

The new circuit incorporated a potentiometer to adjust how hard the JTPS was driven. The adjusts the current available on the output and allowed the device to be ‘tuned’ for efficiency.

As you may be able to see above the new power supply creates a very slighter lower light. On a simple light meter this equates to around 5% less light.

Positioned side by side both with fresh batteries I compared the run time of both and found them to be almost the same. Albeit this time the device has only one battery. The new circuit actually lasted longer than the old circuit even with a single battery but in the last 3-4 days of the test the light lost about 30% of brightness.

The new power supply in effect doubled the usable run time of the light.