Instructables
Picture of 3 Watt LED Pail Lamp
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In this Instructable, I will show you how to build an LED desk lamp from scrap materials. With the exception of the LEDs, wires, and other components, you can get the other materials for free. Depending on where you get the parts, you can build it for under $5. Typically, a 3 watt LED lamp costs $20. This lamp uses about 5 watts which is a good replacement for compact fluorescent lamp.

In this project, you will learn how to build an LED lamp from a metal can, wire hanger, plastic board, wooden plank, and some electronic components.
 
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Step 1: Materials and Tools

Materials
Switch
3 - 1 watt warm white LEDs
N-channel MOSFET (IRF540) and NPN transistor (2N3904)
1.33 and 100k ohm resistors
26 gauge wires
2 screws and 2 bolts and nuts with washers
12V power supply (9V transformers may give you 12V)
Epoxy
Hot glue
Heatsink paste
Wooden plank
Corrugated plastic board
Wire hanger
Wide can with metal base

Tools
Hot glue
Pliers
Soldering iron
Drill driver
X-acto knife
Sanding tool or tool sharpener

Step 2: Prepare the Lamp Shade

Can Selection
When selecting a can, make sure the bottom is metal so that it heatsink the LEDs and current regulator. The bigger the can, the more wattage it can handle. Feel free to try 3W LEDs. With a 15 cm wide can, the temperature did not exceed 40°C  after running the lamp continuously.

Trim the can
The lamp shade requires cutting the bottom portion of the can, leaving two inches of its height. The trimmed edges should be filed and folded with a plier. Do not cut yourself while doing this. It is much safer if you can find a shallow can like a cookie tin so that you can avoid this step.

Mount the LEDs and MOSFET
To mount the LEDs and the MOSFET, apply heatsink paste to the centre and epoxy to the outer edges. Firmly press them onto the flat area of the can and let it set for a few hours before soldering soldering.
martik7776 months ago

Why not use a LM2596?

http://www.ebay.ca/itm/DC-DC-Buck-Converter-Step-Down-Module-LM2596-Power-Supply-Output-1-23V-30V-/181227591312?pt=LH_DefaultDomain_0&hash=item2a32019690&_uhb=1

acunliffe111 months ago
Hello. Would you mind sharing how you got the 12v power supply?
hanlin_y (author)  acunliffe111 months ago
I got it from used electronics.