Custom SkyRay King SRK Driver

Flashlight Modding and DIY Parts
1

Everybody knows about the SkyRay King (SRK) flashlight/snowflake (no two are alike or made by the same company or have the same driver). 3 XML light smaller than a beer can, 4x18650 battery pack, ton ’o lumens in the palm of your hand for way less bucks than a tank of gas.

Nice light, but kind of a sucky driver. Or drivers. Crappy PWM, only two modes, iffy drive current, large parasitic drain, etc. Well, I had enough of mine, so I decided to build my own driver… I’m currently testing the firmware with a 24 x 380 mAh AMC7135 chips on an XML2/T6/3C SRK.

8 AMC7135 regulator chips per LED - regulated 3.05 amps per LED. One could stack more…
ATTINY85 CPU (8K of flash memory, no running out of code space anytime soon)
Thermal monitoring (sensor is on the CPU chip)
Battery monitoring.
VERY low parasitic drain (a 24 AMC board measured less than 10 microamps)
15 kHz PWM
Handy pry hole for removing the press-fit driver.

Been going ape with the firmware (very much a work in progress):
PWM modes: moon, 3.125, 6.25, 12.5, 25, 33, 50, 100%
Ramping (2 second and 4 second)
Slow strobe (10 Hz)
Fast strobe (16 Hz)
Random strobe (8-20 Hz random pulses)
Morse code (i.e. SOS)
Beacon (biips every second)
Alpine distress beacon
Status (blinks battery voltage and temperature)

If the light is on:
Advances to next mode by short button press.
Goes to previous mode by medium button press.
Shuts off by long button press (or clicking to the OFF mode).

If the light is off:
Hidden mode activated by turning it on with long button press (over 1 sec)
Medium button press turns on last mode used then resets pointer number to the start (i.e. short cycle memory) so the next click starts at the beginning of the mode list.
Short button press turns on in the last mode used (i.e. mode memory) and the next click advances to the next mode.

The driver mode list is programmable. If you hold the button down when you apply power, the mode list is returned to the standard values, the light flashes three times. If you then turn off the power the light is in its factory state. Or, you can select a desired mode and hold the button down until it flashes three times. Repeat for each desired mode (the first mode you store is the “hidden” mode. When you have all your desired modes saved, turn off power to the light and then turn it on again.

Monitors the battery voltage. When it gets low, the light blinks twice and light level is cut in half… the battery voltage should then rise for a while. This repeats until it can’t go any lower. I am seeing a 0.01 volt accuracy.

Monitors the temperature in the driver compartment. The light blinks four times and the light level gradually reduces if it passes a set threshold, comes back to normal level if the temperature drops. If it passes a shutoff value, the light shuts off. I am seeing around a 1-2 degree C accuracy. I now need to find out how the driver CPU temperature corresponds to the case temperature to better set the thresholds.

Edit: updated user interface/features description.

Edit 2: Updated picture, mode info, and temperature protection description.

I got in a workable board and built it up. Measured full up 9 amp board parasitic drain at less than 10 microamps. In my 3 x XML2/T6/3C on copper sinkpad SRK measured:

Moon: 0.25 lumens (might be around 1 lumen with plain XML’s)
Other modes: 50, 210, 550, 770, 1200, 2600 lumens (with SRK driver it was 1800 lumens)

2

Sounds great, wish I had the skills to do that! Will you be offering these, would love a better SRK driver.

3

Reading awesome :slight_smile: If you sell these, it seems I have to buy a SRK :smiley:

4

Looks good! Do you have a price in mind? :slight_smile:

5

Please lets your Admirers, Know when the Magic Begins for the Rest of Us!!

6

My SRK deserves that.
Make that driver available soon:-)

7

I’m interested too, just received my WB SRK and while it’s bright, I’m actually more impressed by my ZL SC52:s output considering it’s size…

8

This would instantly make me love my SRK. Provided it doesn’t cost more than an SRK… that is even if you’d make it available. Very cool!

9

so when you say boards, you mean more than one.

awaiting group buy thread!

10

Very cool! count me in if you sell them.

11

Not sure if this is going to turn into a group buy… But count me in for one too! Not sure if the 3xXML 3x18650 sky ray will use the same driver, bit if it doesn’t, should not have a problem finding an owner

12

Impressive stuff! The interface sounds great and board is a great looking design. Nice big pads to solder to as well. 8)

If you decide to make these available to the rest of us (and I'm sure hoping you do!) you could sell it with just the MCU programmed and installed and whatever else except for the AMC7135 chips so we can save you some labor and finish them up on our own. Just a thought. ;)

13

Sweet stuff man I’d be in for couple when they are available so keep me in mind.

14

I don’t think that I will be building up assembled units, but if there is enough demand I could have them professionally built. The assembly house that I use has around a $500 minimum, so it might be doable for around 100 boards. I would need to find a source for full reels of affordable AMC7135 chips.

Otherwise, I could sell blank boards or maybe kits of parts. I ordered the prototype boards from OSHPARK. They do boards in multiples of three. They were around $16 for three boards. For 100 boards, SeeedStudio should be quite a bit less. Assuming professional assembly, a completed board should be less than $20.

I forgot to mention another feature in the firmware… battery sag compensation. If you are in a PWM mode and the battery voltage falls below a set value (where the regulator chips can no longer regulate), it starts increasing the PWM value to help compensate for the reduced voltage. Not all that sure that I like it… there is the potential for a little flicker around the threshold voltage and since it increases the current draw on the low batteries, it will reduce the time until the light has to shut down.

15

Wow! Great looking board and look at all those features! Yike! Not sure I'll ever need all those programmed features, but interested in a board for sure.

I'm a little bit scared of how difficult will be to memorize how many settings one can have with one button only... maybe I'd prefer just 3-4 modes preprogrammed (from moonlight to fullblast) without blinkies and be very well set!

Let us know if/when those will be available.

16

If you can compile a C program for the Atmel chip (i.e. WINAVR) and program the chip, the driver code is very easy to setup for whatever modes and features you want… I am looking into making the modes programmable from the light.

17

Great job on your build :slight_smile:
I would be in for a kit or any other way you would do this.

I think I would need 2 because this would be so great of a setup I would buy another SRK!!!

18

either way, i will be in for one… kit, assembled….

19

Quick quesion: is (or are) there any conditions( s ) one could utilize to program a function that informs the user that Vbatt has dropped or will imminently drop below the point needed for regulation (e.g. very quick and subtle double PWM blink back and forth from 100 down to 50% or similar)?

It’s superfluous but as a flashie I’ve always wanted that feature. Done properly I think one should have to be looking for it in order to see such a notification.

20

I was avoiding SRK because it's stupid modes but with this driver, situation would change for sure so, if I ever manage to get SRK for 15$ (or at least under 20$) I will definitivly buy this driver.

Anyway, subscribed and watching :)