I have finally finished my aspheric SST-90 Mag-Lite, but let's start at the beginnig of the story.
Everything started back in summer 2009, dyson72 and me finished our first homemade mod, a minimag with a direct driven ssc-p4. It was quiet bright, but not bright enough, so we decided to go for the ssc-p7, which was the brightest affordable led at that time.
But then problem begann to start...,
what batteries should we use?,
how do we regulate the current?,
and finally how do we mount the p7?
Last things first, dyson72 as professional lathe and milling machine operator was like, "ahh that shouldn't be that hard, i can lathe something tomorrow. We just need to messure a few...". Anyway he kept his word and the next day we had some nice ssc-p7 heatsinks.
So i had to keep on working on the power supplying part of the flashlight. First fo all i decided to use A123 batteries, because they are a lot safer than the "China Lithiums" and i already made bad experiences with exploding batteries. Since the voltage von three a123 batteries is around 11 volts i had to design a buck driver for the led.
Buck driver? "Can't be too difficult!", now more than two years later i realise how wrong i was. The first three attempts went up in the magic blue smoke on ignition. The fourth one worked, but i wasn't quiet happy with it. It wasn't a led buck driver, but more of a constant voltage buck regulator with a linear current regulator. But finally after nearly one year was gone i had a working ssc-p7 flashlight.
A few month later the SST-90 was annouced, so we bought some, since they were the ideal led for a high power aspheric build with the single chip emitter. So again dyson72 made some lovely heatsinks for us within a few days, while i almost spent a year creating a driver. The driver i created in that time was capable of 9 amps in theory.
But guess what happend?
No, you're wrong. No blue smoke, but it became nearly 100°C in less than a minute, so way to hot to use inside a flashlight. So i had to begin from scratch building a 9 amp buck driver.
Since i'm not an electrical engineer it ended in endless hours of reading datasheets and explanations.
As a few of you, who also tried to build a driver from scratch, may have found out, it is one thing to know how it works, but another thing building one. Finding the right components and dimension them right is quiet difficult.
In October 2010 finally the sst-90 buck driver was finished. The first time i fired it up it was like "Ouch, thats bright".
After a few test i had the confirmation that this was the first real and complet success, here are the specs ans measured thing of the driver:
- input voltage 8-16V
- output current 9A
- switching frequency 500kHz
- efficiency 84-87% (depending on input voltage)
A few weeks later also the pcb was with the mcu was ready and i could fit everything together. Some little mess-ups in the software and the pcb with the avr mcu later and the final version of the aspheric sst-90 build was complete.
Some of the features:
- variable dim speed
- 10bit pwm solution
- programable strobe
- overtemperatur shutdown
- voltage indicator using leds in the switch of the Mag-Lite
- all settings are alterable via pc or smartphone
Yes i do know that the last features is a bit over overengineered and but its just a gimmick, since i had some bluetooth modules lying around. You don't belive my, my Mag-Lite has bluetooth?, then check out the video as well.
There was one last problem to solve, we noticed during some outdoor test. The aspheric lense needed a bezel, because otherwise the spread of light blinded you all the time. Since this was a work that fell into dyson72's resort, it was done within a week. So one nice morning he sent me this picture of the lovely black anodized bezels:
This, i think, is the right moment to actually thank him for all the nice bezels heatsinks etc. he created for me, the trust he put in me and the time he waited patiently while i messed it up.
So now we come the most important part: Pictures!! : ) I know you're tired reading my german's bad english, so here we go:
Modified vs. original switch
The SSC-P7 and SST-90
Aspheric lens form DX
The heatsink with mounted SST-90
Veiled profanity removed.