Sunday, August 31, 2014

Olight S20 clone with MELD

I wanted to try putting MELD into an 18650 light, so I looked around and found this: the Solarstorm SC02, which is a clone of the Olight S20. It's a pretty good buy at $15, better machining than I expected at that price. The firmware is awful, as is the norm, so I promptly gutted it:

 I kept the original PCB and stripped off all components except the tantalum input capacitor. This build wouldn't make sense to use MELD hardware in since it will never run on a primary cell, and it should have a higher current on white than the 1.5A that MELD3 is capable of. This one would be run only on secondary cells so I used linear regulators controlled by a PIC16F1825 running the linear version of MELD 2.13 firmware.
The LED board was made using the two-layer method I came up with on my Blackshadow mod, so that the white XP-L gets better thermal performance.

 I glued the PIC upside-down onto the stripped PCB and started wiring. The PIC needs 7 connections: 4 outputs, power, ground, and the switch input.
I then started stacking up the AMC7135 regulators. Here's the four that run the color components. They have a pair of wires that ground them together, and individual output wires that will run up to the LEDs.

 After those 4 were wired to the PIC, I started on the 6 that will be paralleled to run the white emitter (at 2.1 amps). I made them in two groups of 3 to share the current load between two sets of wires, and to make them physically more flexible for when everything has to be fit into the pill.

Here are all the regulators wired up, insulated with kapton, and the wiring bundled into two groups to pass through the holes.
The driver fit fine, but I was just about at the limit of how much could be fit into the cavity. Here's the LED board going on, with thermal grease under it.

 And here's the result of wiring in the individual LEDs.
To get the spacing just right, I cut the original plastic insulator so it had room for the extra LEDs, and then used it under the reflector.
Finished product!
Here's a video that goes over the latest firmare:
And here's the config menu:

Saturday, August 2, 2014

MELDv3 in Fenix HL50 & Sunwayman C10R

MELDv3 boards came in! This version brings big improvements to the SEPIC converter on the white channel, mostly in the area of thermal performance. It also makes an electrical change that allows the SEPIC to run well at much lower battery levels if the light is running on primary cells.

  The inductors are much bigger to better handle high current, so to avoid increasing the stack height I rearranged the daughter board so that they are both on the top side.

I did two projects right away with the new boards, one of which is to upgrade my new Fenix HL50 headlamp. I was very excited when this headlamp was released because single-CR123 headlamps are rare and I don't like any other battery setups, but of course the UI is terrible and needed an upgrade.

As soon as I got it, I opened it up to see how much room there was. The construction is pretty good. Here you can see the stock driver with a daughter board that sits vertically:

I was able to fit MELDv3 by removing the inductors and free wiring them up in the vertical space.

My standard MELD LED board with XB-H and XQ parts fit with one edge filed down. I also had to drill out the reflector slightly to get it around the LEDs. Here's the LED board installed and wired up:

And the finished result, the perfect headlamp:

And here's the second project with MELDv3, a Sunwayman C10R. I really like the construction on the C10R. It has a nice big reflector so I was able to fit an XP-size LED board in it with an XP-L as the white emitter. MELDv3 went in pretty easily by epoxying a momentary switch onto the main board:

Here it is with wires attached, going into the head of the light. Not shown here is a grounding ring needed to make contact with the body (this difficult grounding is my only complaint about the design of the C10R). Also shown is the MELD XP LED board with all LEDs installed and notches cut to fit the wires:

And all wired up:

Nitecore EX11 with MELD.EX

In continuing my trend of putting RGBWUV and my MELD UI in every light possible, I got a hold of the discontinued Nitecore EX11, which uses piston drive (which I love and have worked with before). I wanted to fit the full MELD2 driver into it, but there is just not enough room in the pill with the piston drive mechanism. I ended up designing a custom board stack that gets rid of all the inductive converters and just uses AMC7135 regulators (1 per color channel, 3 for white). This means the light is restricted to rechargeable cells, unfortunately.

The daughter board actually came so close to the wall of the pill that I had to notch it out to pass wires through from the main board. The entire thing is run by the same PIC16F1825 as regular MELD boards, and it runs the same firmware (with a compile option for linear lights, which makes a few slight changes).

Here's the schematic for the main board:

And the daughter:

Four connections go between main and daughter board. The main board has the positive battery contact and the contact ring for the piston. Since my total available height was very small, I intentionally aligned the regulator on the bottom of the daughter to sit above the PIC, which is shorter than the regulators on the main board. This lets them stack together into a pretty short assembly:

Here's the pill completed, and an XML color wired up for electrical test:

The other challenge with this light is that the reflector opening wasn't big enough to fit a MELD LED board. I didn't want to ruin it by drilling it out, so I went back to a crazy technique I've used before of mounting the color LEDs around the reflector in individual holes. This process started with wiring them up in mid-air:

I then drilled four holes evenly spaced around the reflector, about midway up. Then to reduce the depth to get the LEDs farther out, I filed down around the holes until the wall was about a millimeter thick. I carefully arranged the LEDs and the wires to get the LEDs centered in the holes, and glued them down with thermal epoxy. This was a painstaking process because I had to hold the LEDs in place while the epoxy cured, and I had to do it four separate times so that the epoxy was facing up and wouldn't drip down. 

Here's the result:

And the back of the driver:

It all turned out great, although the color beam patterns are terrible, as expected. The white beam is perfect, and isn't noticeably affected by the color emitters.