James

Hacking “Holiday Living” Tea Lights

Dec 312011

Holiday Living LED Tealight

Just goofing around today with all my Xmas stuff. Thought this might be interesting to someone.

Have you ever wondered what makes one of these LED lamps flicker? I did too. So, one of the lamps had to volunteer to be opened up for a little closer inspection.

I was shocked at the simplicity of the lamp. One CR2032 coin cell battery keeps the lamp flickering for hours. Saying the lamp is flickering is a stretch. Seems more likely the lamp is randomly jumping between half a dozen set PWM values. Still, how do they do that? There is just the battery, a switch, and an amber LED. How does the LED flicker at all?

Well, turns out, the LED has a tiny ASIC built right into the plastic of the LED. The tiny ASIC is “encapsulated” into the LED itself.

Below are a some more closeup pictures of the LED. I took these pictures by holding my little camera up to the eye piece of my microscope. Continue reading »

EPS – Magnet Encoder Reverse Engineering

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Dec 162011

EPS Magnetic Encoder Probing

Very Cool! The encoder works as expected.

After tracing the encoder signals back to the ASIC, I was able to use the LSA to easily probe the signals coming from the encoder board. Well, I shouldn’t say easily because is was tough to get the grabbers on the ASIC pins without shorting them together. In fact, on my first attempt I did have a pair of pins shorted together. However, once the short condition was removed, the ECU didn’t seem to suffer.

The encoder signals make sense for a three phase BLDC motor application. Have a look at the following LSA plot to see the five digital signals coming from the encoder board. Note, the encoder board is bolted on the back of the motor. See my previous post for pictures of the encoder board. Continue reading »

EPS Teardown

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Dec 152011

EPS (Electric Power Steering) Module

EPS (Electric Power Steering)

Hardware Teardown & Hacking

Starting a new series today where you can follow along as I teardown (maybe repurpose) an old EPS module. I’ve been keeping a couple of these old module in my stash for a long time, always with the idea of ripping them apart for all the goodies within.

Note, clicking on any image below will pop-up a larger high resolution version.

First step is to pull the module apart by removing the motor. Continue reading »

Muffin Fan Based Tin Can Wood Gas Camp Stove

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Nov 242011

Wood Gas Camp Stove - G4

Yet another tin can wood stove, I know, I know. Still, I’ve discovered a few things that may make your next stove build a little easier. What follows below are my trials and tribulations at build a really good working camp stove. Note, I’m still experimenting with certain aspects of the design. Always more experimenting to do.

My inspiration came from an article in Make Magazine which described building a tin can wood gas camp stove. Here is a link to the Make magazine article. The Make article inspired me to build my own stove. My primary goal was to be able to boil water (for instant coffee) while on Boy Scout camp-outs. Oh I know, it would much easier to build an alcohol stove (much cleaner and all – and easier to build too). However, there is something cool about being able to cook using wood. Plus, wood is in endless supply while on Boy Scout camp-outs. Will be nice to have a little stove heater on cold winter camp-out nights. A stove heater that I don’t have to worry about in terms of running out of fuel! Oh, I know what your thinking, “What about the battery for the muffin fan? Won’t that go flat in a hurry?” Well, using 2500 mA/hr batteries we’re looking at over 30 hours of run time. Continue reading »

Cree XLamp CXA2011 LED Array

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Sep 062011

Cree CXA2011

Super Bright HBLED from Cree!

So, Cree was good enough to send me a free sample of their new XLamp HBLED. In truth, this is an LED array packaged on a single die. Very interesting and VERY bright. I’m gonna have to get some serious sun glasses. Right now I’m still seeing spots.

Sample Specs:

CREE-CXA2011-3000k

o Min Flux 780 lm@ 270mA , Tj = 85C
- Equivalent to 50 to 55 Watt Incandescent Bulb
o My Sample = 3000k Warm White
o Typical Vf = 40V @ 270mA & 85C
o Max Current = 1000mA
o $15 to $20 Bucks Each at Digikey

Heatsink:

A heatsink is absolutely required before powering up the LED. Without a heatsink the LED will quickly runaway in temperature! My first heatsink was simply a 4″ square piece of 1/8″ glass. With just 100mA of current the glass right behind the LED measured 85ºC. The glass was not good enough at wicking away the heat. Continue reading »

Hello WordPress!

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Aug 052011

Making the Switch

I’m making the switch from Drupal to WordPress today! Now, it’s just a mater of porting all my old junk over with me.

Thanks,

Jim

mBed / AX-12A Servo Motor Hacking

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Jun 032011

AX-12A

Based on a project I have in mind I started playing around with the AX-12A servo motor from Robotis (a Japanese company). The AX-12A is a newer version of the old AX-12+ servo motor. It’s my understanding that the 12A is just a redesign of the plastics – the electronics are the same between the two versions. Still, the naming the new version 12A is confusing to this English speaker. Should have called the new version “++”.

Anyway, below is stuff about connecting a AX-12+ to your mbed development board. Continue reading »

Final LCD Project

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Apr 132011

Well, I had big plan for this LCD thing. After many many hours I’m calling Uncle! I give. The plan was to have this blue LCD floating on a wire stalk above the STM32 Discover board. There is just one problem, the display is almost translucent so things behind the display make it hard to see what’s being display on the screen. What’s needed is a white background – preferably a background that is also generating light. You know, a LED back-light.

For more on the LCD hardware have a look at this link where I covered info about the display.

TI Evalbot Review

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Apr 122011

Quickly little post concerning my recent messing around with my new TI Evalbot.

At $150 bucks this is not an inexpensive kit to buy. Below are a couple of pictures and my first impressions.

The kit is rather easy to assemble. However, the wheels are tough to assemble. The PCB wheel plates press onto the shaft of the motor. Three plates then must be aligned so that two set screws can be screwed through the three plates. It takes a lot of force on the poor motor to get all the plates and set screws mounted.
Continue reading »

Another Copper LCD

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Mar 062011

The Sparkfun LCD is OK – but, it seems really old (surplus). So, I went looking for something new (but similar). Ultimately, I found something interesting at Mouser from a company called Electronic Assembly. Seems they have taken a COG (chip on glass) display and fused PCB legs onto it. The price also helped – only $12 bucks. The displays are monochrome and have a graphic format of 102×64 pixels. The displays are designed to interface to a micro using a SPI bus. Note, these version of displays that use a SPI interface are read only. The display has no MISO pin to allow the display to be read. The Sparkfun / Nokia 5110 display was the same – no MISO pin.

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