Slashdot Mirror

this + this = paparazzi-proof . Sell 'em to celebs for $2500 a pop.

As an EE who started off with one of those 50-in-one kits when I was 8, I have a few recommendations. I had a 200-in-one, but the more impressive projects on it required so many wires it was nigh-impossible to get things to stay working. Put one in and two fall out.

You can start with one of those kits, but once you get to the point where you'll really learn what you're doing, go look for books and kits separately. Look for books by Forrest Mims III and Don Lancaster (TTL Cookbook and CMOS Cookbook are classics). Check their sites out as well.

As for parts sources, for online shopping, I'd recommend Digi-Key. Jameco is a little pricey, but they have some really interesting parts, including a lot of older stuff. All Electronics is a place I used to buy from a lot; they have a lot of manufacturer surplus parts, so it's kind of like shopping in a flea market or surplus auction. Another surplus shop is MPJA. Newark and Mouser are good places to look when you want some specific part that Digi-Key doesn't have.

For starters, you'll want to buy a modular breadboard, and one of the pre-cut wire kits for them. Or, if you want to blow some more dough, you might want to get one of the Analog Design Lab or Digital Design Lab things that has a bunch of things like power supplies, LEDs, and switches integrated into it already. Also look for parts assortments, like resistor and capacitor assortments (e.g. Digi-Key items RS125-ND and PHD1-KIT-ND). If you're going to be doing digital work, you'll probably want to get lots (20 or so) of 10K resistors (for pullups) and 0.1 uF capacitors (for decoupling).

Radio Shack is where you go as a last resort. Their selection is lousy and prices are worse.

A 30 second search turns up this lamp+inverter.

http://www.mpja.com/productview.asp?product=14840+ LA

Search a bit longer to find one the right size :)

http://www.mpja.com/productview.asp?product=15835+ PS

That should feed 6 Mini-ITX rigs running at full load.

I second that (except maybe the LUG, not all Linux users are wireheads too).

I can't stress enough that you use the right tools; a cheap-ass iron from radio shack ain't gonna cut it in my opinion. I got a very decent soldering station for $35 a few months back and I am quite pleased with it.

I bought one of these for $35 a few months ago. While a Weller/Unger unit may be better (I've used them), I have absolutely zero complaints about this unit (it even comes with a spare heating element).

The same unit is offered elsewhere for as low as $30, unbranded.

Unfortunately, a lot of cases have decorative plastic front bezels that don't let air thru, even though they seem to have a grill in the front.

On all my cases, I use a 7" diameter AC fan on the front. I cut a hole thru the plastic bezel, thru the sheetmetal, and mount a 240 volt AC 7" (6.75") diameter fan on the front, blowing in so as not to fight with the power supply fan.

Using a 240 volt fan on a 120 volt system makes it run slow so it is not noisy. You could also use a 120 volt fan and a speed control suitable for inductive loads ( a light dimmer usually isn't). The ideal is to use a 200 volt fan made for the Japanese market (where the voltage is 100 or 200 volts, vs the 120/240 in the USA) but these are a little hard to find.

You absolutely need to have outlet area to dump the hot air, and I try to put my cards in every other pci slot, and leave out the blanks covering the slots in between. In this way you make a card cage like in the mainframes, where air used to flow between every board.

The fans are cheap on the surplus market, if you check the ads in Nuts and Volts magazine, you will find lots of surplus places listed. If you get a used fan and it has noisy bearings, you can pull them, read the part numbers, and order replacements for them from a bearing place like E. B. Atmus.

Once you make the proper holes in your case and put in a big fan, you should get lower temps than you do with the cover off.

If you want to be less extreme you can use smaller 12 volt fans, just make sure you cut the holes to let air in and out.

Here are some cheap fans at marlin p jones. The 24 volt fans may not run at all on 12 volts, unfortunately, but the 12 volt ones should run on the 7 volts you get between +12V and +5V on your power supply.

Good luck!

From Atmel: 8051.

Some drivers/latches from Micrel.

And of course some LED blocks from Sun LED.

The 8051 handles incoming serial data as well as acting as a 'RAM DAC' to load the lines on the Micrels which act as line drivers to the LED displays.

The Micrel's can be bit-banged in a serial-ish protocol which corellates to outputs on the 8-16 pins on each micrel (ie: think of it as programming a multipin output chip via a serialish link).

The 8051 constantly changes which row of LED block its updating and goes about it's business. Ideally, the 8051 should be changing rows 70 times a second for a good clean refresh rate.

These really aren't any different from the LCD modules you can pick up from Jameco, Hosfelt, or MPJA (or perhaps Digikey).

And lets not forget Find Chips for all of your parts searching needs.

Ok, you can find a 5V to 12V DC to DC converter at MPJA but it only supports 1A of current.

You might give it a try, though, since the laptop in charging mode should consume less than one amp. I doubt you'll have any issues with putting 6v in instead of 5v, but buy a few (they're cheap) and find out.

Get a car adaptor (cigarette lighter type) that powers your laptop in a car and hook it up to the DC to DC converter. In a pinch, if you need more current, your friend can use two or more converters with .1 ohm resisters to supply more current (one resister on the output of each supply, then the output from the resisters can go together)

If your friend can build one, then he should not have too much problem finding a boost switching regulator that'll take 4-8 volts and output 12V at an amp or more from one of the suppliers listed above. In some cases the WebBench from national semiconductor will design it for you, and they will even sell you all the parts and a suitable PCB for under $20 for some converters.

Switching supplies are difficult to debug and are considered somewhat of a black art among EE types, which is why I was warning you away from it before.

Good luck! -Adam

Build the case yourself, and use a small powersupply from MPJA or All Electronics

It can be done for less than $30. Those places also have plastic and metal project cases that would probably do fine as a computer case.

• Marlin P. Jones - Cheap surplus stuff. May or may not work
  
• Mouser - My favorite catalog right now. A whole lot of stuff, good prices. Look in the Jameco catalog to find what you want (nice color pictures help), and actually order it from Mouser (which has a boring catalog).
  
• Digikey - order anything here you can't get from Mouser.
  
• Radio Shack - if you don't mind paying a 400% markup ($1.50 for a quad NAND gate??!) or if you need it at 6pm on a Saturday night, suck it up and go here
  
• Fry's - last I was in the valley, they had a pretty low selection compared to a real distributor. Prices were better than Radio Shack though.
  

If you want ideas for a project, hanging around in the back of Radio Shack might get you started, but I'd encourage you to read manufacturer app notes. Phillips has all sorts of consumer audio/video stuff you could build all laid out in their app notes.

Check out things like the PIC or SX microcontrollers. For ~$10 you and the price of a cheap ROM programmer kit, you can have incredible design flexibility

Yeah, there's a certain appeal to using lots of 74xx chips, but there's really no reason to when it's smaller, cheaper, and much more flexible when you put it on a microcontroller. And VHDL/Verilog may both suck at first compared to the beauty of _real_ hardware, but their potential for semi-intelligent glue logic between your microcontrollers, memory, system busses, etc cannot be overlooked. And, unlike 74xx's, you can rewire without laying out your entire circuit again.

I thought about this after my digital design class. I'd built a "single board" computer before with a whopping 2K of RAM and another 2K of EEPROM, so I wanted to make an expanded version with real I/O. Character LCD displays are really cheap, as in $7-$15 for small ones. Graphics displays might cost you $50-$100 for a small monochrome one. Check out Marlin P Jones for okay deals on surplus stuff.

For my own project, I decided that the display portion alone was difficult enough to merit an A in my lab, so I built a PIC microcontroller-based NTSC video game (Breakout -- check out the links at the bottom of the page for PIC Tetris!). Looking at Altera's UP1 FPGA evaluation board, displaying VGA at 640x480x60Hz with 16 colors isn't even very difficult (Altera UP1 at GA Tech). Try using a standard method of output like this, and you'll have a lot more fun and be able to do a lot more than with a $7 20x2 LCD module.

Input is pretty much the same. Sure, you could use a custom keypad, but why bother when you can interface with a PS/2 mouse or keyboard? Specs are widely available, and this will impress people much more than a row of DIP switches. This can be done on a relatively small FPGA (~20K gates) which Altera's university program sells on full development boards for $150.

For even more fun, try interfacing with compact flash for storage (Circuit Cellar Article). Then realize that you've just implemented a basic IDE interface, and expand it to do hard drives. Design a character generator for your NTSC or VGA output, write a simple filesystem, and have a whole computer with standard parts that you built yourself!

If that's still too intimidating, just look at company Application notes for ideas. You can find some strange ideas and take them all the way.

I'm setting up a B&W cam (from Marlin P Jones & Associates) for the same purpose (baby cam). The nice thing is that CCD cameras are very infra-red sensitive unless they incorporate an IR filter. (You can test yours by observing how well it "sees" an IR remote's beam.) I've wired up two banks of IR LEDs as a light source (20 50-cent LED's in series/parallel). Baby can sleep in complete darkness while Big Brother (well, Big Mother and Big Father) watch.

Good cameras (from MPJA, SuperCircuits, and others) are cheap enough that there really is no reason to fool with toys like the camera mentioned in the base article. The X10 stuff is as cheap and is at least barely usable (with good lighting and short distances). But if you're half-way handy with electronics, you can do a lot better assembling a system yourself for just a bit more money.

-Ed