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(no subject) [Jan. 2nd, 2007|01:23 pm]

Ok, I'm going to try here.
I am running a few highpower LED's (some 5watt, some multichips as bright as a 5watt Lux from CAO Group) with a big ol' 13.2v power supply. I am sure they would rather have a nice stable DC voltage and current.
But, what can I get that is cheap? I feel like I shouldn't be running these puppies with 13.2v, or am I wrong, and they will be fine as long as they are cooled well?
Is there a way to lower the powersupply's output to exactly 12v, and be a bit more stable?

Thanks all.
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(no subject) [Nov. 14th, 2006|01:09 pm]

In the upcoming months, our company will introduce new led product line - Led Cross and Led Heart.
I would like to know your opinion about our new products?
We are planning to create some new stuff in this product line, so if you have any ideas, I would really appreciate your comments. May be you would like to wear apples, roses ...
Thanks in advance for you comments )

Посмотреть в полный размер, 72,34 КБ, 800x575Collapse )

Посмотреть в полный размер, 72,62 КБ, 800x601Collapse )
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Cheapest way to connect two boards together at a right angle? [Oct. 17th, 2006|08:34 pm]

[mood |curiouscurious]

In my current project, I need to hook up a few 14-segment LED displays to the driving electronics. I want to put this in a nice wooden enclosure, which will probably mean that the PCB holding the LED displays has to be placed at an angle on the PCB holding the rest of the circuit.

I noticed that some proto boards have 'fingers', just like a PC expansion card has. Does anyone know where I can get connectors for that? Or is there some other, cost-effective way to connect two boards together?

Sure, I can always resort to soldering wires between the two boards, but that is a lot of work and isn't as cool. :)
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mYpod : CompactFlash-based, in-dash mp3 player [Oct. 9th, 2006|03:37 pm]

Yay...after all this being too busy, too lazy, or any number of other excuses, one more project finally off my stack. The "mYpod"* is a small CompactFlash-based mp3 player I built from leftover spare parts from a bottom-secret government project, free samples and a standalone mp3 decoder chip.

(Click thumbnails for larger image)


  • Supports CompactFlash media up to 2GBytes officially (FAT16 file system limitation); 4GBytes if you "relax" (i.e. violate) the FAT16 specification a little by setting a 64KB cluster size (Win2k/XP will allow this, but Win98 and below will bitch loudly and not read the card)

  • Actual, real, full FAT16 implementation - handles fragmented files, deleted files, etc. (You'd be amazed how many card-based music players, and even some digital cameras, do not fit this description, or at least not reliably)

  • Playback of mp3s with bitrates all the way up to the maximum mp3 bitrate of 320KByte/sec

  • Display title and artist from ID3 tag if present (display filename if no ID3 present), and elapsed time

  • Saves the currently-playing song when powered off - picks up where it left off

  • Song selection: next, previous, "skip 10", pause and menus (e.g. restart card from the beginning)

  • Buttons light up at night like a glow-in-the-dark Bomb Pop

  • Line-in and line-out from stereo available on front panel (anything plugged into line-in is switched in instead of mp3 player)

An early view of the guts, before they were enclosed in anything

One evening a year or two ago, GJM and I were about to head home from work and talking about part of an environmental monitoring system we were developing at the time. This was a handheld data-retreival unit that queried the environmental loggers in-the-field and recorded their wireless data to a CompactFlash card. I remember jokingly saying, "Hey... we have a memory card, A/D, processor, LCD and buttons...how many extra parts do you think it would take to turn this into a music player?" Next thing I know we've got a couple beers cracked and are laying out a quick-n-dirty mp3 player board in an unused corner of a layout set to go out that night.

Packaging this quick 'n dirty design as a truly portable device would have been non-trivial (and, I got a Creative Nomad as a gift sometime between the start and end of this project); it would be much easier to package it into a car-stereo size enclosure. My car already came with this plastic tray (officially for holding papers, garage door clickers, etc.) bolted into the spare bay where an auxiliary radio component would go (or the bottom half of those huge, double-height stock radios), so I took it out, drilled some holes and screwed the board and extra parts directly into it.

Most of the parts were leftover lab spares, such as the PIC microcontrollers (scrapped from the Real Project because of a silicon defect in the revision we had; they can act unreliably above 4MHz and therefore can't be used in production gear), the membrane keypad and the LCD. The only major extras needed were the STA013 mp3 decoder ($12) and a stereo DAC (free sample from Cypress Semiconductor)** to convert the decompressed digital (PCM) audio from the STA013 to real sound.

Guts during assembly. The large tall chip toward the front, hiding behind the too-fast oscillator (more on this in a bit) is the mp3 decoder, the square 64-pin bitch-to-solder in back is the PIC. (Click for larger image)

For the front panel, I grabbed a piece of Lexan left over from building the terrarium and of course, cut a bunch of holes in it. I started off with the usual score-and-break method of cutting the Lexan, but when it came to inner cuts (e.g. the rectangular holes for the CF card and LCD) consulted my dis-is-how-we-do-it-in-da-ghetto handbook, laid a hot soldering iron against the back of my X-Acto knife blade and pressed it into the piece. Like a hot knife through buttah! Using a straight edge as a guide, this provided straight, clean cuts, which were touched up a bit with a small hand file. Round holes were cut by making a pilot hole with a small drill bit, working up to larger and larger drills until the desired size was reached. The Lexan has a tendency to grab the drill bit and suck it in (depending on the intricacies of classical physics, this either yanks your drill out of your hands and into the piece, or yanks the piece out of whatever's holding it, potentially snapping it), so don't go diving immediately in with the large bits.

The keypad features an adhesive backing and insertable overlay for the button graphics - being the perfectionist that I am, I doodled some arrows and symbols on a piece of paper and slid it in. Since the front panel is clear, and surprisingly, the buttons themselves are translucent, it was easy to stick a few colored LEDs on a piece of Veroboard behind them, angled and distanced so that they cast a tight circle of light on the entirety of only one button each. I was originally going to have this turn on automatically when the headlights were turned on, but couldn't find such a signal on the radio's wiring harness. The LCD unfortunately comes without any backlighting, and no way in hell to add any since it's mounted flush against a very opaque PCB full of traces. A metal guard ring completely surrounds the glass; if removed, the glass ceases displaying anything and falls out (the metal band presses it tight against a zebra strip that connects it to the board).

The button panel, without sexy backlighting. You can see how much effort I spent on it! ;) (click for larger image)

Software / Featuritis:
A couple features are missing, either because they were accidental, or too much of a pain to implement. The most notable is fast-forward. The firmware is already handling FAT16 fragmentation transparently in the background; all the decoder requires is bits, as fast as you can stuff them in. Mp3 files are made up of many small time segments called frames, which often incestuously share bits with previous frames, so you can't just play the file at 10x by dropping 9 out of every 10 frames. All you get from this is a bunch of blips and pops... fast-forwarding an mp3 turns out to be non-trivial, so it is not implemented here. The other non-implemented "feature" is Chipmunk Mode. The mp3 decoder runs off of a very precise master clock, typically around 14MHz. Following this (internal to the decoder) is a Phase-Locked Loop system of clock multipliers/dividers that can be software adjusted to provide a correct timebase from a wide variety of input clocks. While I was testing, I got the sensation that everything from my player sounded a little "sharp". Indeed, a side-by-side comparison between the early mYpod and WinAmp confirmed that the same 3.5-minute song finished almost 10 seconds faster on mYpod. Turns out I had the PLL set for a slower master clock than I used, so it was playing back too fast. I discovered the PLL settings are very, very adjustable; you could make all your favorite artists sound like demons or chipmunks. Unfortunately, this is not exactly a "fast-forward" feature (by the time you speed it up enough to be a decent FF, it's too high and whiny to be intelligible - besides, the micro can't pump data out that fast anyway), so I set the correct speed and didn't leave provisions for messing with it via the front panel.

For the firmware - that was actually the most annoying part of this project, a lot of assembly coding. The FAT16 stuff was actually written already for the most part, as part of the actual work project (otherwise, I'd release the code here). All the fiddly bits (buttons and menu system, LCD scroller, play timer, hunting for ID3 tags, position-saving hack to an already crufty file handler, etc.), and getting them to play nice with one another (e.g. does the play timer stop when playback is paused? What's the easiest way to restore the song title/info on the LCD after it's been overwritten with a menu?), still had to be done though. The PIC programmer supplies and requires 5V to program, but the mp3 decoder chip can only handle 3.3V. The solution to this was to load the Jolt serial-port bootloader onto the PIC before soldering the decoder in (and hope I never introduced something in my code that overwrote the bootloader). Sending new firmware over the serial port, the PIC can self-program at 3.3V.

Last but not least, this beast had to be connected to the headunit somehow. Pioneer decided that all good headunits should have line-ins, but ensconce them in this proprietary 11-pin "IP-BUS"*** connector (with differential inputs, no less). Bah. Luckily, breakaway pin headers plus heat shrink equal reasonable facsimile of funny plug, and the differential inputs work fine by just dumping single-ended signal into one side and grounding the other.

So yeah... it sounds good! Now I just need to put the TrashAmp back together (strip away the melty bits, etc.) for that phat window-rattling bass, yo.

* my brother calls it my mpthriller - then again, he's got some shizzle on his nizzle.

** I only sampled it because I couldn't get it from Digikey or any other decent distributor. Ohh, that was a mistake. Samples came at a cost of about 6 months of horny Cypress rep calling me about how the chip's working out for me, when he can come over and show off the full product line, and how soon I'll be ready for those 10,000 units...

*** as in like, Intellectual Property Bus? As in, if any competitors try to reverse-engineer our funny plug and make something compatable, there will be hell (or IP lawyers) to pay? All right, maybe it stands for "Interconnected Peripherals" or something.

Posted to: gadget_design, diy_electronics
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Transceivers, Cell Phones, and RS-232 [Jun. 4th, 2006|09:53 pm]

Transceivers, Cell Phones, and RS-232. Ok, here is my situation, I would like to have my computer communicate large distances to a Microcontroller. I can find simple RS-232 transceivers that will get the job done, but will only communicate a distance of 20 Meters. I found one company that www.maxstream.com that sells RS-232 RF modems that can go up to 30 miles (if you have an extreme antenna). But I would like to communicate with my MCU device over greater distances. Perhaps 100 miles, but it is within a cell site. I don’t mind using a cell phone, but I don’t know how. Could anyone help me out here?
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(no subject) [Feb. 22nd, 2006|02:04 pm]

I just got myself one of the Kingston DataTraveler USB Memory sticks. I have to say these things are mighty nifty. So nifty in fact that I think that I might try and use one for data storage on one of my robotic projects.

Question is, how would one do this? Anyone have a pointer in the right direction?

I primarily do most of my work with BS/2 MCs.. so any links based on that would be great.
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Enclosures? [Feb. 13th, 2006|04:14 pm]

Hi there! I'm pretty new to the whole EE thing, I'm just starting to teach myself about this stuff. May end up going back to school for EE at some point, but that's all beside the point. Here's what I'm here about:

I have a few ideas for nifty / useless little gadgets that I want to build, and I'm not having any trouble finding parts (DigiKey is my friend...), but all the project enclosures (aka: "boxes") I'm finding look like 1970s TV remotes or garage door openers.

So, does anyone have any resources for slightly more stylish boxes?
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The Mega-Flash [Dec. 11th, 2005|05:57 pm]
Ok, so I've been purchasing LEDs from SuperBrightLEDs.com and I also got some Luxeon stars. Anyone know of any places that also sell high-power LEDs?

I was tinkering with the idea of creating a massive strobe light using either suprbrights or Luxeons, I'm just not sure if the LEDs come to brightness fast enough to act as a strobe. I gotta get a 555 hooked up to a transistor and experiment.
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(no subject) [Oct. 6th, 2005|01:53 pm]


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Hello everyone. [Jul. 4th, 2005|01:35 am]

I am currently attending ITT tech, working on my associates in CEET. I am into a lot of different stuff, but currently I am trying to get my cell phone to trigger an amplifier circuit attached to a microphone, then that is supposed to trigger a monostable 555 timer, and then that is supposed to trigger an astable 555 timer, and power 4 superbrite LEDs. But for some reason the amplifier circuit will not amplify the ringtone from my cell phone, I am using LM741s as amplifiers. If anyone wants to lend a helping hand, or needs more information, it would be greatly appreciated!
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