In an energy-efficient household, a 50W halogen lamp is not-done. Moreover, halogen lamps can be dangerous contraptions as touching them when they are in operation can cause nasty burns. In a well-isolated mansion, the extra heat generated by the halogen bulb and the transformer, are undesired side-effects. The weight of the lump of iron in the transformer are an indicator of a less than optimal power supply. If illuminating a keyboard is the sole purpose of the lamp, it just doesn't feel right. That is why I have decided to transform this lamp to a 3W LED lamp. The results are described in the current article.
Disassembling electrical appliances can be hazardous. The current article is not intended as a DIY manual, it serves only as a written report of an experiment that I conducted. Don't try this at home, and if you do, don't claim that I did not warn you. OliNo nor the author of the article accept any liability.
Replacing a 50W halogen bulp by LEDs is pretty simple and efficient. The amount of light from the LEDs is enough for usage as desk lamp, the conversion process is simple and the result saves quite a bit of energy. The plan is to change the 50W halogen bulb by three 1Watt LEDs. Three 1W warm white LEDs will be connected in a string (series).
The original transformer is removed from the lamp's base and replaced by a 350 mA current source. The original dimmer with switch is retained but only the switch function remains as the current source used is not dimmable.
Safety-wise, the switch is on the secondary side of the current source so 220V is safely kept away from the touchable parts. All appliances on the desktop are connected to a mains power strip which is switched off when not in use, in order to kill all stand-by energy waste.
As a picture paints a thousand words, here we go:
 A sheet of two-sided adhesive heat conducting material, a hole punch and a 1W LED. |
 Punch out 1 cm diameter disks from the heat conducting pad. |
 Stick the LED onto the heat-conductive pad. |
 The old lump of iron and electronics on the left hand is removed and replaced by the tiny current source (little black box) seen on the right. |
 Three LEDs have been placed in series. Each LED is 1W and draws a 350mA current |
 An energy-efficient 3W LED desktop lamp |