This project let me accomplish two things I wanted to do, all in one light. I have always wanted to try my hand at making a bright one cell light that runs off a single D cell, and I had a new three die power LED I wanted to test out. These two desires resulted in this, the D1:
The LED used in this project was supplied by ArcMania (thanks Mike). The LED is rated for 160 lumens output at 700ma. Now that's impressive, even when compared to the new Luxeon K2 which would require 1500mA to come anywhere close to the output of these new LEDs. These new LEDs come in a six legged ceramic package where each of the LED dies have connections to the leads. This allows each LED die to be independently illuminated and controlled. The LED dies are mounted on a metal stud that extends through the back of the ceramic case so that it can be mounted on a heatsink. The large low dome lens is actually made of a soft, clear silicone type compound that is very soft and flexible like RTV. However, as shown in the photo below, the phosphor emitting area is quite large, maybe ten times, or more, larger than a Luxeon LED.
This large emitting area does not lend itself well to forming a tight, bright flashlight beam spot like smaller emitting surface LEDs produce. Since the phosphor light emitting area is so large, the expectations were that this would produce a very broad beam, but with 160 Lumens to work with, it should still be pretty bright and impressive. And with the one D cell form, the light should be adaptable for use as a handlebar bike light. In a bike light application, the broad beam produced would make it a good headlight beam compared to a normal flashlight's pencil thin beam.
This is the integrated heatsink and light engine used in this project. The LED specs call for 700mA, which works out to about 233mA per LED die for the 160 lumen output. However, I've never been one to be real conservative when testing out new parts, so what the heck, if driven at 900-1000mA I figured the LED should produce at least 180 to 200 lumens. So each of the seperate LED dies got its own converter, which drives each of the LED dies at 350mA from the single D cell. The LED dies did test out with a very low vfd of about 3.1V at 350mA, so even with the extra power excessive thermal heating should not be a problem. With a vfd of only 3.1 volts, and one amp of total current, the LED would only be running at about 3.1 watts. Not bad at all for a device that should produce around 200 lumens of light.
Modifying a 2D Mag into a short 1D light also requires making a tail cap switch for on/off operation. This setup uses an adapter plate made from part of a heatsink to adapt a Brinkmann AAA tail cap switch for use in the Mag tail cap.
The switch is held in the adapter plate by a treaded ring (cut from Legend battery tube) and is easily replaced should the need arise. The switch and adapter plate are just press fit into the stock tail cap that has had a 9/16 inch hole bored in the end for the switch button to pass through.
Cutting down the 2D battery tube was a real challenge as my mini lathe won't accept anything that big in diameter into the chuck. So, a lot of pain staking messing around was needed to make the mini lathe do the tricks required to shorten the battery tube for use with one D cell. After a very long and slow machining process, it finally all came together.
To drive this LED near one amp of current from a single D cell battery requires a whopping 3 amps of input current. So full brightness really is not possible from an alkaline D cell, as alkaline D cells can't maintain current that high but for very brief period. However, good NiMh D cells can deliver that level of current without problems. Also, using an adapter it is possible to run the light off 4 AA NiMh cells for faster recharge times compared to D cells. Using a 11000mAh NiMh D cell, or 4 2400mAh AA cells, the expected run time is around 3+ hours.
Results -
The light output from this new LED in my estimation is at least 200 lumens, probably a little higher. While it does not foucus to a sharp bright spot like a regular flashlight, it does have a bright central spot that fades evenly into a huge bright corona of side spill light.
Here's a shot of the D1 (right) compared to a 2D Mag with BIN X4T 5W Luxeon (left) powered by six AA cells running at about 1.4 Amps.
Conclusions -
While this LED does not produce the typical tight flashlight beam, it does produce a huge amount of useful light. The beam produced with a 2D Mag reflector would be very well suited for use in a bike light, providing lots of side spill to illuminate off the side of trails and road ways while trowing plenty of light forward to see where you're going. As a flashlight it's still very useful and bright if you don't need to project a beam spot long distances (beyond 100 yards).
Over all, in my opinion, building this light was worth the effort involved, and resulted in a unique single D cell flashlight. Very bright and compact, it can also provide bright emergency room lighting by pointing at the celing and standing it on the tail cap.
Lambda
The LED used in this project was supplied by ArcMania (thanks Mike). The LED is rated for 160 lumens output at 700ma. Now that's impressive, even when compared to the new Luxeon K2 which would require 1500mA to come anywhere close to the output of these new LEDs. These new LEDs come in a six legged ceramic package where each of the LED dies have connections to the leads. This allows each LED die to be independently illuminated and controlled. The LED dies are mounted on a metal stud that extends through the back of the ceramic case so that it can be mounted on a heatsink. The large low dome lens is actually made of a soft, clear silicone type compound that is very soft and flexible like RTV. However, as shown in the photo below, the phosphor emitting area is quite large, maybe ten times, or more, larger than a Luxeon LED.
This large emitting area does not lend itself well to forming a tight, bright flashlight beam spot like smaller emitting surface LEDs produce. Since the phosphor light emitting area is so large, the expectations were that this would produce a very broad beam, but with 160 Lumens to work with, it should still be pretty bright and impressive. And with the one D cell form, the light should be adaptable for use as a handlebar bike light. In a bike light application, the broad beam produced would make it a good headlight beam compared to a normal flashlight's pencil thin beam.
This is the integrated heatsink and light engine used in this project. The LED specs call for 700mA, which works out to about 233mA per LED die for the 160 lumen output. However, I've never been one to be real conservative when testing out new parts, so what the heck, if driven at 900-1000mA I figured the LED should produce at least 180 to 200 lumens. So each of the seperate LED dies got its own converter, which drives each of the LED dies at 350mA from the single D cell. The LED dies did test out with a very low vfd of about 3.1V at 350mA, so even with the extra power excessive thermal heating should not be a problem. With a vfd of only 3.1 volts, and one amp of total current, the LED would only be running at about 3.1 watts. Not bad at all for a device that should produce around 200 lumens of light.
Modifying a 2D Mag into a short 1D light also requires making a tail cap switch for on/off operation. This setup uses an adapter plate made from part of a heatsink to adapt a Brinkmann AAA tail cap switch for use in the Mag tail cap.
The switch is held in the adapter plate by a treaded ring (cut from Legend battery tube) and is easily replaced should the need arise. The switch and adapter plate are just press fit into the stock tail cap that has had a 9/16 inch hole bored in the end for the switch button to pass through.
Cutting down the 2D battery tube was a real challenge as my mini lathe won't accept anything that big in diameter into the chuck. So, a lot of pain staking messing around was needed to make the mini lathe do the tricks required to shorten the battery tube for use with one D cell. After a very long and slow machining process, it finally all came together.
To drive this LED near one amp of current from a single D cell battery requires a whopping 3 amps of input current. So full brightness really is not possible from an alkaline D cell, as alkaline D cells can't maintain current that high but for very brief period. However, good NiMh D cells can deliver that level of current without problems. Also, using an adapter it is possible to run the light off 4 AA NiMh cells for faster recharge times compared to D cells. Using a 11000mAh NiMh D cell, or 4 2400mAh AA cells, the expected run time is around 3+ hours.
Results -
The light output from this new LED in my estimation is at least 200 lumens, probably a little higher. While it does not foucus to a sharp bright spot like a regular flashlight, it does have a bright central spot that fades evenly into a huge bright corona of side spill light.
Here's a shot of the D1 (right) compared to a 2D Mag with BIN X4T 5W Luxeon (left) powered by six AA cells running at about 1.4 Amps.
Conclusions -
While this LED does not produce the typical tight flashlight beam, it does produce a huge amount of useful light. The beam produced with a 2D Mag reflector would be very well suited for use in a bike light, providing lots of side spill to illuminate off the side of trails and road ways while trowing plenty of light forward to see where you're going. As a flashlight it's still very useful and bright if you don't need to project a beam spot long distances (beyond 100 yards).
Over all, in my opinion, building this light was worth the effort involved, and resulted in a unique single D cell flashlight. Very bright and compact, it can also provide bright emergency room lighting by pointing at the celing and standing it on the tail cap.
Lambda
