Origa.me

I have one of those cheap desk lamps which I use as a bedside reading light. The problem with it is that the bulb keeps blowing and it always seems to take me ages to buy a replacement. As LEDs can be pretty bright nowadays and have a much longer life expectancy (when subjected to the recommended current levels) as well as lower power consumption, I decided to convert the lamp to use LEDs.

First thing was to check out the power supply. It outputs 12VAC so this needed rectifying (the big black square on the circuit board). I then put it through a 5V regulator and added a smoothing capacitor. With an appropriate resistor to limit current through the LEDs, the circuit was complete.

Next job was to adapt the lamp housing to accept the new circuit. It was a fairly simple process to cut a suitably sized aperture with a Dremel (or similar) tool. I then secured everything in place with tape - a bit of a bodge but it does the job. Put it all together and it's finished.

The resulting lamp is sufficiently bright for night time reading. The LED output is quite tightly focussed so I can have a page well lit from over my shoulder without keeping my Wife awake - another of the complaints with the old filament lamp. Finally, power consumption should be about 10% of the filament lamp, give or take, which I consider to be a pretty good result.

A tip for sourcing the LEDs: go to ebay - you'll get them much cheaper than Maplin. The ones I bought are apparently 15000mcd which is pretty bright.

Gallery images

The donor lamp Date: 08/17/1999 Views: 332	The LED circuit Date: 08/17/1999 Views: 397	The prepared aperture Date: 08/17/1999 Views: 340
The LED circuit in place Date: 08/17/1999 Views: 332	Lighting up for the first time Date: 08/17/1999 Views: 360	The finished lamp Date: 08/17/1999 Views: 334
Testing in the dark Date: 08/17/1999 Views: 350