Instructables
Picture of 3W LED Hat Lamp - 300 Lumens
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  • 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.
 
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Step 1: Materials

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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
Hat
Velcro straps

Tools
Drill
Scissors
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
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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.
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?
thanks!
hanlin_y (author)  shock0032 years ago
Thanks! I got them at Lee's Electronics. I think this is the one.
http://www.ebay.com/itm/JST-2-Pin-Connector-Plug-w-Wire-Male-Female-x-10-Pairs-/110930746245?pt=Radio_Control_Parts_Accessories&hash=item19d3fcdb85
ivanjacob2 years ago
cool.
hanlin_y (author)  ivanjacob2 years ago
Thanks!