Headlamp desk lamp

[Monkeyjim]

Hello, 

I am sure you have all seen the desk lamps made from old car,motorcycle,bicycle or tractor headlamps. Plenty on Pinterest to view.

I have a tractor plough lamp that takes a 40w p45t bulb and was thinking about how it could be repurposed.

My question is how are they converted from mains to 12v? 
Other than the purpose made new retro lamps available I assume up-cycled originals are 12v as a old headlamp does not lend itself well to being modified where the bulb locates thus retaining the 12v bulb configuration makes sense. 
I know there are plug in wall adaptors and led drivers but the drivers may be to large to fit in the back of a lamp (a 48w I have seen is 14cm long) and a adaptor transformer wire may be short and will need joining to whatever goes into the lamp for additional length and aesthetically a twisted coloured flex would look better going into a lamp.
 

Would appreciate your thoughts on how it is done. 
David

 

[Geoff1946]

Use a plug in power supply, like a phone charger but 12volts DC. They cost about £5. You can then play around with led 12volt lamps with no danger to yourself. It just becomes a meccano type construction exercise.

But a 1 amp one and you will have plenty of power, (up to 12 watts in fact) It's surprising how bright led lamps can be.

 

[ProDave]

The OP says his light has a 40W lamp, so you will need a 4A 12V power supply (which could supply up to 48W)

 

[Geoff1946]

The OP says his light has a 40W lamp, so you will need a 4A 12V power supply (which could supply up to 48W)

True if sticking to an incandescent lamp. I didn't make myself clear that I was suggesting changing to an LED lamp, which could be brighter and cooler with a much lower wattage.