Due to a huge influx of spam in my comment moderation queue, I have disabled comment posting for the time being.
Once I get educated on combating wordpress comment spam, I’ll turn them back on, until then, feel free to email me your comments, and I will post them on a comments page or something.
MintLite – The Luxeon Powered Mint Tin Flashlight!
This idea has been rattling around in my head for more than a month now, and I finally have thought it out enough to do some doodling in Eagle. The basic idea is built around a six watt Luxeon K2. I plan to use a pair of 2.5aH lithium batteries to provide approximately eighteen watt-hours of power. The Luxeon will be controlled by a microcontroller, providing different brightness levels, as well as protecting the luxeon from excessive current when the batteries are fully charged. The microcontroller will also monitor the battery voltage; dimming the light as needed and eventually shutting down completely to prevent over-discharge. The light will contain it’s own battery charger, powered by USB using the MAX1811. The MAX1811 will charge a single lithium cell (or cells in parallel) at up to 500mA off a self-powered USB port. The 1811 allows charging from a bus-powered port as well, but for sake of simplicity, I will ignore that option.
The circuit keeps things fairly simple. Switch Q1 provides pwm control of the luxeon. Header SW1 will connect to some sort of switch, for turning the light on and off, and changing brightness. The MAX1811, IC2, takes 4.3 to 6.5 volts as input, and regulates it to 4.2 volts for charging the lithium cells. Charging status is indicated by LED2, which will light when the charger is in bulk charging mode (current mode).The microcontroller, IC1, is a PIC12F683. The 683 provides a lot of bells and whistles for such a small chip. I will be using analog input 0 to monitor the battery voltage. General purpose input 2 will monitor the charging status, perhaps to disable charging when the batteries are in bulk charging mode. General purpose input 4 will use an internal pull-up resistor to monitor the switch. General purpose output 5 is controlling a mosfet transistor responsible for PWM of the led.
The pcb layout is in it’s early stages, and designed mainly around parts I have on hand. I don’t think I’ll actually prototype this PCB, since it’s much too large, and the wrong shape. Whether it gets printed or not, it was fun to draw. There are two main things I want to change. First the FET (Q1) in the TO252 package is rated at something like sixty amps – way more than I need for this project. ON Semiconductor has some nice SOT23 fets rated at 4 amps that should fit the bill nicely, and save a lot of space. Secondly, I need to find a smt version of the usb connector, perhaps a mini usb instead.
Hopefully this weekend I’ll be able to breadboard this circuit and see how it all goes together. Stay tuned for “Part II”.
I’ve been rolling a few idears around in the brain box, in preperation for re-opening the lab, since the summer heat is on its way out.
Number 1: Eclipse mints based usb charger / battery. I like the esclipse tin better than altoids gum, since its more square and only has a small opening via a hinged lid at one end. It should hold two lithium ion cells and a small PCB quite nicely. My plan is to make the gizmo with a small switch (or automatic possibly), so it can both charge/operate USB devices. or recharge off a USB host.
Number 2: Ice breakers mints based palm light / flashlight. Take a metal ice breakers mint tin, slap in some lithium cells, a USB re-charging circuit, add a 6 watt luxeon K2 and presto… nice and bright palm-sized flashlight. I also thought about adding a USB capabile microcontroller, and having the device show up as an HID gizmo in windows … perhaps allow programming of different brightness levels, check battery, etc.
Number 3: USB controlled Luxeon 1 based keyboard light. Using some semi rigid tubing of some sorts, and a not-yet-found small metal enclosure, create a usb HID based keyboard light for using on my laptop.
Thats all I got for now – till next time!
Wow, July is over already, and worse, I haven’t written anything for the entire month!
As you may or may not know, I’m in the United States, and we’ve been having a bit of a hot-spell lately. Typical summers in my mid-western state of Michigan are mid 70’s and low 80’s, going into the 60’s at night. However, this July, the weather is playing it a little different. Most of the days have been 80+, and the nights are in the mid 70’s. Today was a real scorcher … most of the time the weather folks are wrong for my area, due to a micro-climate imposed by Lake Michigan not more than a few miles from my house. However, they were spot on today. As I awoke this morning it was 72F at 7:30 am, 85 by 9:30 and 95 by noon! By the dog-day afternoon, it was over 100, and the humidity was equally high. Tomorrow and Wednesday are expected to be repeat performances, so all I have to say about that is – glad I bought a big AC early in July, before they all sold out! My AC covers the first floor living areas, however the lab is on the second floor, beneath a poorly insulated and darkly colored asphalt shingle roof. So, long story short, the Lab is closed due to extreme temperatures.
I do have some things in the back-log to write about, including a wireless project mid June, a computer water cooling project in early July, and a new four-legged addition to my family.
Work has been very busy lately, which is good, work while there is work to be done, fill up the coffers!
Ahh well, there, July will not be a hole in my archives, there’s one post, boring as it is!
ttyl!
Some time has passed since my last post, and for that I am sorry. I like to write about my technical endeavors, however, I’ve been feeling “out of time” lately. Its not that I work late or anything like that, time just seems to disappear. I get home from work around 6, catch up on personal emails and some news, then its time for dinner, and before I know it, it’s 11 pm! Where did those 5 hours go!?
I have a list of things to write about, and I’ll be taking a little time off from the daily grind over the Independence Day holiday to catch up on stuff. Hopefully I can get some of these things written down, and make room in the ‘ol brain for keeping better track of time.
On a maintenance note, I’ve finally gotten around to upgrading my wordpress to 2.0.2. The constant stream of spam which I hope to keep hidden from my readers has prompted this move. I have some new spam-fighting plug-ins working behind the scenes, hopefully they won’t interfere with valid comments.
Jeeze, almost an entire month gone by, and nothing new from me?
Well, almost … I did finally fill in the [Image Missing] place holders in my pcb fab article.
I’ve been doing a little tinkering, but also working outside … spring time has arrived for my little microcosm and the outdoors needs tending to. I’ve also been having a bit of a mole problem, so lots of time has been wasted trying to deal with them.
I have been in the lab a little, working on a few projects, and burning out parts … I burned my last ‘free’ tps61040 boost regulator, so rather than ask TI for more freebies, I’ll buy some this time, luckily they’re not too expensive. Also I managed to bust a red Luxeon III Star. I had two of them wired in series and hooked ’em to a 12v supply, without any manner of current limiting … needless to say, it was bright for an instant and then dark. Luckily only one star was killed, the other lives on. Here’s a few post mortem pictures, I removed the little lens, which really was filled with silicone goo just like Lumileds claims!
You can see a little bit of the goo remaining on the heatsink structure, as well as the fine gold bond wires and fine grid used to power the die.
Here’s a bit of a closer view.
This die still works… when I poke at it with the leads of a 3v battery pack, it lights up blindingly bright… wonder how long it will survive before oxygen or something else kills it?
Sorry if I interrupted anyone’s reading … don’t you like my shoot from the hip method of working on live site code, instead of some backup / test site?
I have added a link to the end of each posting, allowing readers to easily bookmark posts they would like to share with the del.icio.us community.
The sidebar has been on quite a growing streak lately – first a bunch of new statistic driven links, and now many many new categories.
Since my post count is getting pretty big, I decided now would be a good time to organize it, rather than wait for it to get even larger. So I have gone back through every post, and further classified them into different categories.
It should make it easier to find things now, instead of it being all lumped under “Project”.
I have added some new plugins for wordpress that lets me get a better idea of which posts are popular and which have never been read at all.
Readers, you will notice on the sidebar, there is now a “Most Popular” section. It will list out the overall most popular when viewing the main page or viewing individual posts / pages. If you go into the monthly or category archives, it will list out the most popular posts for that month or category.
Each post also has a popularity readout at the end of the post… this is probably going away, once I find where that little bit of code was added.
I have also added a plugin that lets me track referrers, links, enter pages, exit pages, etc. I don’t think the readers can see any of the stats it produces. I may make a stats page for everyone once I get to understand these plugins a bit better.
For post popularity I am using Alex King’s Popularity Contest
For the general http stats I am using Anders Holte Nielsen’s Counterize
Greetings to Hack A Day and Delicious users.
Thanks for stopping by!
You may have noticed, I haven’t written anything in a while. Well, I’ve got the regular laundry list of excuses, work etc… but in all honesty, I haven’t been doing much with projects lately. I have been reading a LOT about switchmode power supplies, trying to come up with a ‘universal’ or at least flexible high-power LED driver.
I’ve requested a lot of samples from some big name semiconductor suppliers – latest to arrive is some cutting edge high frequency stuff from Linear.
I also recently finished a ‘utility project’, a controller for my water filter – I’ll post about that in a few hours.