Picture of 3W LED Hat Lamp - 300 Lumens
  • Hands free
  • Dimmable with 3 settings
  • Run times: 2-3 hours (high), 4-6 hours (medium), 20-30 hours (low)
  • Uses 3 AA batteries
  • Options for other LED colors
This hat lamp was inspired by ProdMod who designed a 3W LED video camera light.

Step 1: Materials

3W Hat Lamp
3W White LED
10 or 30 degree LED lens with holder
Heatsink (2cm x 2cm)
2 pin connectors
Heat shrink tubing
Clear Epoxy

Battery Holder with Brightness Control
1 ohm 1/2 watt resistor
10 ohm 1/4 watt resistor
3 AA rechargeable batteries
On-off-on switch
4 AA battery holder (with cover and on-off switch)

Hat Lamp Holder
Velcro straps

Dremel with grinding disc
Soldering iron
Hot melt glue gun
Alligator clips (to hold parts when setting the epoxy)

Step 3: Grind Battery Contact Holder

Picture of Grind Battery Contact Holder

Step 4: Drill a hole for the switch and wiring

Picture of Drill a hole for the switch and wiring
Drill a hole for the brightness control switch. A hot soldering iron may be used to enlarge the hole. Warning: When heating the plastic, do this in a ventillated area.

Step 6: Brightness Control Switch

Two switches will be used here. The switch included with the battery holder is used as the on/off switch. The on-off-on switch combined with the built-in switch allows three different brightness settings.

If using red/yellow/IR LEDs, a 2 ohm resistor is required. It can be soldered to the LED externally if you plan on using different colors.

Brightness settings (for 3.8V 3W LEDs)
Direct drive - 1000mA
1 ohm - 500mA
10 ohm - 100mA

Note: The recommended forward current for 3W LEDs is 700 mA  but you can drive them a little higher. These LEDs usually have enough internal resistance for 3 AA batteries if you drive them directly. If using Luxeon Rebel and certain Cree emitters, you may need a minimum resistor value of 0.5 ohm for the high setting to limit the current to 1000 mA.
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shock0032 years ago
Cool instructable.
Where do you buy the 2-pin connectors? been looking for these guys for some of my own little projects. Did you get them at Digikey?
hanlin_y (author)  shock0032 years ago
Thanks! I got them at Lee's Electronics. I think this is the one.
ivanjacob2 years ago
hanlin_y (author)  ivanjacob2 years ago