Wednesday, August 29, 2012

Parts ordered

I placed orders with Mouser and DigiKey today for the parts required to build the i4004. To get the best prices I bought all the parts I'll need for all 5 planned boards, plus some spares: 700 BSS83 4-terminal MOSFETs, 1200 FDV301N 3-terminal MOSFETs, 500 4.7K ohm resistors, 100 2.2K ohm resistors, some PC/104-style connectors, and a collection of bypass and charge storage capacitors. I also bought a syringe (yes, that's the way it comes) of solder paste to make the boards easier to assemble.

One thing that really struck me is how little some of these parts cost. The 500 4.7K resistors cost less than 2 US dollars total. 100 2.2K resistors were 63 cents. These are 1% tolerance parts!

And then there's the price difference between seemingly similar parts: the BSS83s are 5.6 times the price of the FDV301Ns in 1K-unit quantities, and closer to 5.9 times since I only got the 500-unit price. Maybe someone who knows something about materials science can explain the difference to me (unless it's just that the FDV is made in larger quantities).

The parts I ordered from DigiKey have already shipped, and I expect them to arrive Friday. Mouser has a much earlier cut-off time for orders not being shipped overnight, so I expect to see them Saturday, or maybe Tuesday (Monday being a Federal holiday here in the USA).

PCB-Pool estimates that my board will ship a week from tomorrow (Thursday). If the board is fabbed in their relatively new US facility it would show up the next day, which would be a week from Friday. However, if it's coming from Ireland (which I expect) I may have to spring for Saturday delivery to have it for the weekend. They'll be sending me photos of the process (it's a fun option they offer) and I'll post them here as they arrive.

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