I bought a few of these for $8:
http://www.ebay.com.au/itm/261132296135
MAX7219 chip plus a 8x8 LED plus PCB (not assembled).
The MAX7219 alone is around $19 for one from Farnell. OK, it's $8 if you buy 100.
But this kit includes the 64-LED display as well! And the circuit board. And two capacitors and a resistor. And the edge connectors. And the chip socket. And socket strips for the LED display.
They are designed to be daisy-chained (haven't quite got that sorted yet).
retrolefty:
Be sure to make the the small change to the bubuino variant file: pins_arduino.h or the pin mapping for the analog pins will be wrong:// #define analogPinToChannel(p) ( (p) < NUM_ANALOG_INPUTS ? NUM_ANALOG_INPUTS - (p) : -1 )
#define analogPinToChannel(p) ( (p) < NUM_ANALOG_INPUTS ? (NUM_ANALOG_INPUTS-1) - (p) : -1 )
Might be a few other changes to the maniac supplied files, I don't recall at the moment. EDIT: Some people were having reliability problems with the serial port working on the 1284P DIP (but not on bobuino boards!) and lots of different fixes were tried to different effectiveness, but what seemed to nail it for experiencing such problems is changing the low fuse byte to use full swing oscillator: bobuino.bootloader.low_fuses=0xf7 So probably a good change to make on general purposes.
Thanks for the suggestions.
Over the past weekend I went to a local hamfest and picked up a Heathkit ET-3400; it's basically a small 8-bit (Motorola 6800) computer with 512 bytes of memory, some LEDs, a hex keyboard (and 7-segment hex display), ROM monitor software (so you can enter assembler opcodes, and debug, etc) - plus a breadboarding area (which a previous owner had set up a 6821 PIA interface). Also got the manuals for it...
I spent $50.00 for it; Yeah - I could've gotten a Raspberry Pi or a Mega for cheaper - but I can guarantee you neither would be as cool as this monstrosity...hehehe.
picked up a Heathkit ET-3400;
Back in the day I had a Micro Professor which was a similar thing for the Z80 (Z80-based CP/M machines were in vogue). I got a few extras for it, like a Tiny-Basic chip.
Bloody thing got stolen from my office while I was on leave...
http://www.ebay.com/itm/250828820487
10 pcs MAX7219CNG - $4.80, free shipping.
Just sent an order to them, also got:
2PCS Arduino NRF24L01+ Wireless Transceiver Module $2.60
10PCS OPTOCOUPLERS FAIRCHILD/MOTOROLA DIP-6 MOC3041 $3.79
1 Channel Isolated 5V Relay Module $2.18
1PCS IC ATMEL DIP-28 ATMEGA328-PU $3.99 (this is a little high)
and a couple other doodads.. however, when I saw that price you said for 7219's, I figured you may want to snap a few of these up!
This is just getting insane. I wonder if they work?
Anyway just ordered 20 for under $10 including free shipping.
I've ordered so-cheap-its-unbelievable chips from these China sellers. I got some MSGEQ7s
All of them have issues. Some do not work at all. Some work, then fail after some time. They seem like factory rejects... chips that fail QA testing, or not up to par with the published specs.
For personal use, I guess it's okay to gamble with chips from China ebay sellers. But if you're planning on selling your finished product to others, I'd avoid these chinese suppliers that sell chips lower than their retail prices.
Well, I'm well-known for my bottom-feeding on ebay.. and if the device being made was critical in any way, I would use "real" parts purchased from a reputable retailer.. but in reality, almost none of my projects are something I would directly sell or depend upon for any real purpose. I will buy "as-is" and "NOS" as a priority, knowing the risks. The fact is, I feel more comfortable buying from a Shenzen seller with twenty thousand sales on ebay than I do with a Los Angeles seller with sixty sales.. I trust the Shenzen volume seller to care about their reputation more than the new account from California.
In the years I have been grabbing ebay dregs, I only once have gotten trash- a four pack of ATMEGA88's that wouldn't do a thing- and the seller refunded.
"polida" (the vendor for this particular deal) is one that I have bought a number of things from- and if you don't need customer service (language barrier) I haven't had any problems with and tends to ship pretty quickly. I think their angle is sheer volume, if you look at their total number of customers it's in the tens of thousands.
Happily, most of these vendors seem to know their customers are going to be hobbyists and the like- they tend to have a lot of the stuff we tend to buy. Modules of various types (sensors, voltage regulators, SD card, ethernet, etc) can be ridiculously cheap- I have gotten ethernet modules for $3, Bluetooth for $2, and stepper motor controller (ULN2003) plus stepper motor for $3. Outside of the modules, you can always bottom feed on certain items- 2N3904/3906 transistors, ULN2003A Darlington Arrays, LED's of all types, MOSFET's, and a dozen different "uino" clones. I had to dedicate my "real" Arduino Duemilanove to a project for a couple months, so I decided to give (reference to counterfeit product removed by moderator) a try.. they are one of the larger clone outfits. Their prices are hard to beat also, I got a Uno clone, a Proto Shield with 65 jumpers and a mini breadboard, and an LCD keypad (looks suspiciously like liudr's design) shield... all of it for $39 shipped. It's coming from California, so shipping isn't even the couple of weeks of waiting that ordering from China is.. it's just the normal 2-3 days for mail. Today, I am making a 24-channel PWM controller (8 channels of RGB) using AT90S4414.. I bought two TUBES (twenty MCU's, 40-pin AVRs) for $7 TOTAL a while back (I just realized to myself that amounts to just over a penny per GPIO pin!). I have been planning to using them to make quick and dirty SPI-to-1602 LCD interfaces, should work great for the purpose. I am still looking for a good use for the half tube of Dallas 12887+ clocks I bought for TWO BUCKS also. Yes, I know all of these components are likely to be factory seconds or overstocks- but as I said- in several years and dozens of purchases, only ONE has ever been outright bad. One thing is for sure- the vendors take take "Feedback" very seriously and will bend over backwards even on a deal to avoid getting bad feedback, it seems. I wouldn't try to "take advantage" of that, but it does seem they care about those stars a lot.
I will give a report on the (reference to counterfeit product removed by moderator) "uino" when it arrives- but I see no reason for it to be anything other than a good ole basic Uno..
focalist:
Well, I'm well-known for my bottom-feeding on ebay..
Because you keep telling us so! And then you provide the details to prove you're not just a bottom-feeder but an effing hero-class bottom-feeder to boot!
Tell me please, do you use any glass cloth in your epoxy work?
Hehehe..well, it's usually to let folks know when I stumble across something particularly crazily priced (like the 7219's, the recent logic mosfets, etc).
The thing is, I am killing hours when I am cruising that stuff out. Long story short, I have an illness which puts me in the loo for up to five hours a day, sometimes hours at a stretch, many times in tne middle of the night. The internet is what keeps you from going insane... eventually I made kind of a game of browsing for things that slip through the cracks. The reality is that I am surprised how FEW items are garbage.. at the prices I am going for, sometimes from unknown vendors- many times at what has to be a loss. I expect a certain of garbage- and have found that the amount of garbage is surprisingly small. Vendors don't want bad feedback, it's poison to an ebay vendor. I think a certain number of these sales are put out there simply to solicit positive feedback- and I'm okay with that, as long as I am getting a good deal, I'm happy to praise them for it 
It may seem I get things cheaply, but trust me, if you incorporate the hours it takes to find these things, it is anything but cheap!
I've used fiberglass... I have also used cotton gauze, twist ties, and even formed a pour mold of duct tape for use in creating structures never intended or recommended to be composed of an adhesive. If there is a wrong way to do it, rest assured, I have done it or am planning to.... I absolutely love things like epoxy, PVC pipe, duct tape and heat-formable plastics (even those not actually designed to be formed). Another good starting point for inappropriate construction is utility and junction boxes from hardware stores.. and never forget threaded rod. A discount store up the street sells hot melt glue in three temp ranges, big bag of sticks for a couple of bucks. Throw in some drywall screws and plywood, you pretty much can build a mockery of anything decently made. Some day I'll have a 3d printer, until then, pass the epoxy and staplegun...
I'm the guy that mounts heat sinks with hotmelt glue and an attitude of letting fate decide if the magic blue genie will emerge... I actually HAVE mounted power LED's (twelve one watters) to a chunk of a floppy drive made of a hunk of aluminum as a heatsink with hotmelt glue.
Doing things the right way is almost sinful when tinkering, in my eyes. Production, work- another story, real work you do right. For my own personal use, I almost prefer the slight air of danger every time something is powered up...
I had to give up on hot glue. Darn stuff gives way in the AZ heat. Now, that epoxy putty that come in a clear cylinder; that stuff is the bomb.
And, you keep looking, I've jumped in on some of your finds and look forward to doing it again.
I've jumped in on some of your finds and look forward to doing it again.
I too have succumbed to a few of focalist's E-bay finds. The problem is I just order them because the price was so killer and put them away in a parts drawer somewhere and a month or two later I have no memory of what I bought, so It's like I don't have them at all if I don't remember I have them, right?
Darn you focalist.
Lefty
retrolefty:
I've jumped in on some of your finds and look forward to doing it again.
I too have succumbed to a few of focalist's E-bay finds. The problem is I just order them because the price was so killer and put them away in a parts drawer somewhere and a month or two later I have no memory of what I bought, so It's like I don't have them at all if I don't remember I have them, right?
Darn you focalist.
Lefty
I have sort of the same problem. The difference, I think, is that I keep things very well organized. I keep smaller parts in four of the larger units shown on this page (two each of the two types):
http://www.akro-mils.com/Products/Home-Office/Hardware/Hardware-Storage-Cabinets.aspx
I label each bin. For small quantities of small parts, I can get two into each small bin using the dividers. For parts that will not easily fit in these cabinets, I use Sterilite stackable modular boxes from WalMart. These are great, they stack really, really well, even different sizes because the smaller boxes stack 2 or four onto larger boxes. A lot of thought was given to dimensioning these boxes correctly.
http://www.walmart.com/ip/Sterilite-2.7-Quart-Latch-Box-Set-of-6/20699631
WalMart stores sell these individually.
I label everything and, what's more, I go through it once every month or so just to refresh my memory of what I have and maybe some projects I intended to do and forgot.
"Hmmm... what were those ferrites for?" 
The difference, I think, is that I keep things very well organized.
Well see right there is a problem, as I'm not and at my age probably never will get organized.
Lefty
Lefty, that's Geekmas!
Opening a drawer and finding those five bubble envelopes you got, paid a dollar each for, and forgot-- only to open and find the inspiration for the next wildly useless portzebie. Why do I have an industrial ultrasonic transducer designed for use in measuring the volume in tankers? Because it was a buck (though lists for a thousand!). What will I do with it? Stick it on a shelf, and then pull it out when a ping sensor (at five bucks) would work. I saved four bucks, even if it is a thousand dollar part, actually
It's the fact that many of these are so low cost that makes it possible or reasonable to lose things in a drawer for six months until Geekmas... it's not too hard to forget three items costing a total of two dollars that take a month to arrive, especially if you were buying them to shelve them in the first place
I've used sawdust and carpenter's glue to make light mountings. Had a neighbor who made rockets from glass cloth and epoxy but I'd have to do major re-arranging here to begin at it.
Another mix I have yet to try is glass strands in concrete.
3D printer... a dream for me. I want one that can lay fiber and wire, maybe print sockets.
GoForSmoke:
3D printer... a dream for me. I want one that can lay fiber and wire, maybe print sockets.
The first thing that I am going to print with my 3D printer is a 3D printer. And then return the first one.
GoForSmoke:
Had a neighbor who made rockets from glass cloth and epoxy but I'd have to do major re-arranging here to begin at it.Another mix I have yet to try is glass strands in concrete.
I've recently been intrigued by the invention of Concrete Cloth. Cloth impregnated with concrete- they even make it as bags, with an internal bladder, as an instant hardened shelter. Leaf blower to inflate it (like a bouncy house) and then spray it with water, and it hardens overnight. Sterilizable, hardened, drillable for utility installation, all of it. They also can unroll it and make walkways, dams, runoff channels, you name it. Amazingly useful invention:
It's one of those "Geez, I wish I had thought of that" things, we've been doing the same thing forever with fiberglass and paper mache, why it's never been done before now with concrete is just that "Aha!" or "I wonder.." moment, I suppose.. it was invented by university students... and I look at it and instantly imagine it would be a PERFECT shop space. Maybe it's the extremely thinly veiled desire to have a skull-shaped island with a dome, or an underground lair, but for some reason this has that "madman with a soldering iron" feel, don't you think? Suffice to say, I think the stuff makes it worth trying out for yourself, in a poorly done hobby way. Fiberglass matting saturated with portland cement and probably some type of latex (I would use exterior latex semigloss paint. Always add latex to cement, imo- the cost is worth the durability.) would probably work for starters and would be cheap enough to try. Home depot, ten to fifteen bucks you should be able to get a sack of portland cement and the cloth and a quart of noname latex paint.. Heck, they are using canvas, but multilayered. I might consider using the fiber roll padding used for carpet backing possibly. In any case, sounds like cheap and easy enough to try...
I wonder what parts of the USA that thing would be building code compliant for a permanent installation, which I guess is the intent. Still, very cool. I didn't have that vid on with sound. Are there any specs on that like how much weight it can hold on the roof before it collapses?
edit.... Found it:
Have you done any analytical testing on CCS?
The University of Bath has completed Finite Element Analysis of CCS50 structures. The result showed that the shelter can withstand all specified load cases including a person standing on the roof, uneven snow loading and Hurricane force winds. In addition it proved that the shelter can be earth-bermed with up to 0.75m of wet sand on the sides of the structure and 0.5m on the roof.
They didn't answer if adding gun ports would significantly weaken the structure though. ]
Well, they say it's supposed to last ten years.. in many places that isn't considered a permanent structure. I know here in Massachusetts, it has to have a foundation and be expected to have a certain lifespan to be considered a permanent structure as relates to property laws. Especially considering there's no reinforcing bars or anything, that's impressive lifespan for a temporary building! The ribbing where the fabric is stitched forms the load bearing members of the structure.
I have no idea of the price of the things, but in many cases I am sure that it is a fraction of the cost of virtually any other form of construction. The one they show most often is something like 50 square meters... that's a pretty decent area, requiring framing and such with any other construction method. The thing is easier to assemble than a tent.. only takes one person.
I also look at the smaller one, and having grown up in the Midwest where tornadoes are a common thing... if you anchored that thing (and I mean really anchor it) it's rounded shape makes it an almost ideal tornado shelter. Heck, the ability to put up a feedbarn anywhere in a single day with one man... what's that worth to a farm?
I have one of the prefab steel backyard lawnmower and junk sheds, it's running down to the end of it's life- I understand it's over twenty years old. When I looked at what it costs to replace it, you are looking at a thousand dollars or more in many cases- and I know from a mechanic friend who has done it- don't do the "assemble it yourself" kits, ever. Even cheap sheds are five to seven hundred dollars, and even if you just set out to build one yourself out of lumber, you are looking at a few hundred for even the most rudimentary-- and a lot of labor and knowhow to do it if you want it to last a decade or two. If one of the smaller ones was say, five hunded dollars-- it would be a real contender in that market. I know I would think about it... and in the meantime, I take window screen and lay it across the rust holes and hit it with that spray rubber coating (or automotive undercoating spray), and it'll hold for several years.. I am up to three years on one such patch
Another very interesting material I have a yen to play with is UV-cure polymers. In all honesty, I want to build a 3-d printer which utilizes this rather than extrusion.. I think managing a UV LED or laser diode is a lot easier than a feed mechanism and temperature controlled nozzles. Just pump the liquid polymer and expose (harden) it on very precise locations, the extra runs down and is refed into the supply. The media management becomes a simple pump, the "print head" an LED or laser diode. All that's left is a gantry.
