What a long strange trip it’s been…
I started this mod five years ago, but just couldn’t decide on an approach to develop my vision of a twin LED light. So there it sat. And sat…
Early attempts included Luxeon K2’s (what are those?) I was going to use a Maxim MAX5456 dual log taper potentiometer to control the reference voltage of a Linear Tech LT3475 dual 1.5A LED driver IC. I started designing a joystick switch and even toyed with the idea of using a trackball from a PDA. I still think this would be cool, but hard to make waterproof. So there it sat…
So lately I said to myself “self, get off you’re a$$ and finish this thing!”
So, without boring you any further, I introduce – um, I haven’t named it yet…
Ta-da!
<<< Before and After >>>
I bought it from Harbor Freight so long ago that they no longer carry it. Amazon has it here Great Neck 32000 . Because it tail-stands and swivels, I thought the addition of a wide angle flood would make it a perfect light for map reading, playing cards or Cosmic Wimpout while camping.
Here’s a close up look at the two XPG emitters and reflectors. And this is how the wide angle flood spills over everything.
These of course are the requisite beam shots. It’s not an amazing thrower due to the size and texture of the reflector I chose. But the combination of the standard beam and wide beam are quite useful. The standard beam central hot spot is about 16” at 56”, or ±8º. The wide beam spans 100” at 56”, or ±40º. The wide reflector is a Carclo 10170 and the other is from DX or KD, can't remember.
I have access to a PCB milling machine at work, so I used it to make a stack of aluminum plates to heat sink the optics and hold them to the existing bulb holder assembly. Although the head looks large, the swivel hinge takes up a lot of room, I decided to only mount LEDs in there – no drivers. This means the rather snug fit of the heat sink won’t have to be disturbed when working with the driver programming.
I bought and then discarded metal core XPG stars because they didn’t look like they could transfer the heat as well as they should. I snagged an awesome copper core PCB that was lying around the shop and used that for the XPG stars. It was a sample from a PCB house showing their capabilities. I’ve never seen such thick copper cladding before – it must be 6 or 8 oz. The fiber centering ring also serves as an insulator between the reflector and star.
Three uber-flexible wires feed from the LEDs through the swivel point and down to where the head assembly screws to the battery tube. The construction of the battery tube uses an internal snap-ring (like a MagLite), with the switch housing on one side and the base of the head mount on the other. Routing the wires got tricky here as there just isn’t enough room to coil up the length of wire needed to assemble (or disassemble) the switch and head because of the snap-ring.
So, I decided to use a connector between the two. I used spring loaded pogo pins from Mill-Max (0900-1-00-00-00-00-11-0, about $.40 ea at Mouser). This allows for easy disassembly and access to the driver for reprogramming. Two screws hold the head to the driver while sandwiching the snap-ring in between.
The original switch assembly used a clever design where the internal switch housing is separate from the piece that holds the rubber switch seal. There is a sliding taper between the two – such that during assembly the rubber seal is first placed in position from the inside and then the switch assembly slides in and wedges the boot in place, sealing against the inside of the tube. I thought this to be quite clever!
I replaced the stock switch assembly with an array of PCBs to that provide all the structure of the original along with the necessary connections of the new functions. I designed my own driver based on a ST1CC40 3A down converter, running from six AA NiMh cells or even alkaline. There is an alternating switch that selects the wide or narrow LED, an Atmel controller to program dim levels etc. and a low voltage cut-off to protect the cells from deep discharge.
The battery holder came from a fellow CPF’er a looong time ago. It is a MPD (Memory Protection Devices) DU1-M-502. I’m not sure of its availability today. It holds 6 cells in series but both contacts are at one end. Because of this and it being a little small for the D-cell tube, I made PCB discs for each end of the holder. The lower disc just keeps it centered in the tube while the top disc transfers the plus and minus contacts to the driver board through more of those spring loaded contacts. This way the battery cap spring doesn’t carry any current.
Well I sure hope you folks like it, I’m happy to see it finally completed!
Keep your light shining,
Crux
