Let's talk about costs - because when you buy parts in the quantities I am, it's hard to determine exactly what the cost per board is (although we can try).
|Part Name||#/Board||Cost/Part||Cost/Board||Quantity Purchased||Where?||Part Number|
|Bourns PTC Reset Fuse||1||0.134||0.134||10||Newark||83K0399|
|USB B Connector||1||0.646||0.646||5||Newark||14N8154|
|3 Bit DIP Switch||1||0.22||0.22||10||eBay|
|.1uF Ceramic X7R||11||0.008||0.088||4000||Jameco|
|10k 0805 1% Resistor||6||0.008||0.048||Owned|
|4.7k 0805 1% Resistor||1||0.008||0.008||Owned|
|510 0805 1% Resistor||4||0.008||0.032||Owned|
|1k 0805 1% Resistor||5||0.008||0.04||Owned|
|2k 0805 1% Resistor||4||0.008||0.032||Owned|
|4k 0805 1% Resistor||1||0.008||0.008||Owned|
A lot of the 'Owned' stuff is eBay specials. The resistors mostly came from a single resistor sample pack and were, surprisingly, in spec (at least when I pulled them off the strips).
My guess: with zero wastage, $23.37 a board. I'll be soldering manually, so there are some hidden costs:
- I'm going to destroy something, probably some XC95144XLs and IS61LV5128ALs because Murphy's Law. Capitalized, let's call it $32.50 a board with part destruction to be conservative.
- Again, I'm hand soldering - I'm not the best solderer in the world, so the fact that we've got a .5mm pitch 100 pin part means my estimate is around an hour a board. I've got to roll out my kit, gather my supplies, use my paint stripper to recover mistakes, etc.
- I'm not making 10 boards... so I'll have extra parts. You decide whether this matters to you, your spouse, your kids, etc. I'm not counting it because I value the well-stocked parts drawer.
So: $23.37 - $32.50 a board in small quantities, depending on your level of soldering competency. Plus that hour of your time - you'll have to value it yourself (I run a finance web site, and we've discussed that exact topic - you can't use what you make at your day job). In short, if I was selling these and soldering manually, I'd be charging a bit more than $0.