You've got mail!

The mailman doesn't seem to be liking me much lately, annoying bubble envelopes every couple of days, and often multiple on the same day. Having delivered mail myself for a few years I can relate to that, but nevertheless it makes me happy when I hear big things fall on the doormat :D

Today's "harvest": 200 LEDs, 5000 91 Ohm resistors, 5000 150 Ohm resistors.

Also visible on the photo are some wires I stripped and straightened. A colleague of mine gave me a golden tip on how to straighten those wires easily, but that's worth its own post and instructional video ;)

Shopping

Buying electronics on eBay; my favorite way to kill time :)
It's amazing how little you pay for hundreds of components, most of the time it's less than what you'd pay for shipping alone if you'd buy it from some European supplier like Conrad or Elfa. Sure, I have to wait a week or two for the items to arrive, but who cares? Here's a small selection of items that have arrived in the past week:

6 meter of rainbow flat cable, 100 meter 22AWG wire, 100 8P dupont connector housings, 10 electrolytic capacitors, 50 ceramic smd caps, 200 sot-23 transistors, 200 RGB LEDs and 5000 1K ohm 0603 resistors.

Some people ask me if I'm afraid to get ripped off. The answer is no, not really. I've done nearly 100 transactions in the last couple of years, only 1 never arrived, and I blame that on the mail :) None of the items on the photo above have cost me more than $20, so even if an item never arrives, I never lose a significant amount of money. I'd be more bummed by having to wait two more weeks :)

I have a few favorite sellers which I'll pick if the difference isn't too big. They are, in no particular order:
Ele-parts
G&C supermarket
Tayda2009

But most of the time, I'll just try to find the cheapest ;)

Shoppinglist

Here's a list of parts required to build the cube. The given quantities are the minimum, I recommend you get a few extra of each since you (read: me) are bound to make a few mistakes.

• 512 RGB 5mm LEDs, common anode, diffused.
• 200 2N3904 transistors. These are used as switches, 192 for the cathodes, 8 as MOSFET drivers for the anodes. (datasheet)
• 25 74HC595 shift registers (datasheet)
• 8 P-channel power MOSFETs, I'm using IRF9540 in TO-220 package. (datasheet)
• 400 1 KOhm resistors to drive the transistors
• 192 resistors of varying values to use as current limiters for the LEDs. The value depends on the color of the LED and the brightness you want/
• 8 100 Ohm 1 Watt resistors for the MOSFETs
• 8 100 uF electrolytic capacitors for the MOSFETs
• 25 100 nF ceramic capacitors as bypass for the shift registers
• 100 meter 22 AWG wire for the cube

That's just the bare minimum. You'll also need a microcontroller to run the thing, a power supply (5V, 10A = 50Watt at least), something to put your components on and loads of wire to connect it. Since I'm trying to make this look nice under the hood/cube, I've added the following to the shopping list:

• loads of angled pin headers, both single and double row
• dupont female connectors, 8P, 2x4P and 1P
• a couple of meters of 40p rainbow cable
• custom made PCBs, 24 cathode drivers, 1 anode driver
• 25 surface mount LEDs for the drivers
• resistors for aforementioned LEDs

Pretty much all of the parts you can get from China on eBay. Use search terms like "200pcs" and make sure you select "worldwide" as item location. Most of these items only cost a few dollars. LEDs cost about $17 per 200, but surface mount resistors as little as $5 for 5000 pieces and you get free shipping as well. The 100 meter wire I got from the UK (also through eBay) and the PCBs will be manufactured by OshPark.com

You'll need some tools as well of course:

• soldering iron
• solder
• side cutters
• wire stripper or a small sharp knife. I'm using a small snap off knife

And most likely you'll want to create one or more jigs to aid in putting parts together neatly, but I'll cover that in a different post.

I'm planning on making a display to put the cube and all electronics in as well, so some wood, a few acrylic sheets, paint and miscellaneous hardware will be added to the list as well.

That's it for now!