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SheevaPlug Power Supply

 

An Even Newer, Even More Improved V2 Power Supply: Part 5

Now that it is all built and working, what did it all cost?

One basic tenet of having a hobby is that you should never worry about what it costs, or you might realize that it wasn't really worth doing, at least from a financial sense.  In this case, a few people have asked what it would cost to replicate this thing, so I figured it out.  Well, sort of figured it out.  I probably forgot to add in some tax and shipping on some of these things, so don't take these as exact numbers.  Plus, this page was written in 2011, so the prices will go out of style with time.  Fortunately for electronics, the prices tend to go down though, at least on some things.

Bill of materials:

Cost    Qty   Value   Device                Parts
$1      7     0.1uF   CAP0603               C1, C3, C4, C5, C7, C8, C9
        5     1K      RESISTOR              R10, R15, R17, R19, R21
        1     10K     RESISTOR              R12
        2     12.7K   RESISTOR              R1, R3
        1     97K     RESISTOR              R4
        1     100R    RESISTOR1206          R5
        1     147K    RESISTOR              R2
        1     160R    RESISTOR              R11
        4     4K      RESISTOR              R14, R16, R18, R20

$1      2     4.7uF   CAP-TANA-P            C2, C6

$2      1     10K     R-TRIMM3314J          R13

$1      1     PINHD-1X2 JP1
        1     PINHD-2X3 JP3
        1     PINHD-2X5 JP2

$6      4     1751248 1751248               X2, X5, X6, X7
        2     1751264 1751264               X3, X4
        1     1751303 1751303               X1

$2      1     PJ-045 PJ-045                 U$1
        1     PJ-063BH PJ-063BH             U$3

$3      5     FUSE-5X20 FUSE-5X20           F1, F2, F3, F5, F6

$1      2     SWITCH-MOMENTARY-2PTH         S1, S2

$1      1     USBSMD                        X8

$2      3     SSB44 SCHOTTKY-DIODESMD       D1, D2, D3
        1     BAS70 BAS70                   D4
        1     LNJ626W8CRA LED0603           LED1

$3      1     RESONATORPTH RESONATORPTH     Y1
$6      1     AQV25SMD AQV25SMD             K2
$4      1     ATMEGA168-20AU ATMEGA168-20AU U1
$5      1     FT232RL FT232RL               U2
$6      1     LTC4355CS LTC4355             IC1
$8      2     MOSFET-NCHANNEL-SOIC8         IC2, IC3

$4      1     Beeper speaker

Total: $56 for the parts, not including the PCB or LCD display.  Probably round up to $60 to account for wire and heatshrink and other small parts I forgot about.  Those prices are pretty much all for quantity-1.  Higher quantities are cheaper, but even in jillion-unit quantities, the prices might approach only half as much. 

The LCD displays are optional, but way cool.  They are generic 4x20 line character displays using the standard Hitachi controller.  I think mine cost about $25, but that was a few years ago.  They are probably cheaper now.

The circuit boards are $60 each if I get them in the minimum quantity of 2.  They get a cheaper pretty fast if you order more of them (like 10 or 20).

The DC-DC converters are $40 for the 12V output (powers the router), and about $25 for the 5V converter (powers the server).  Both of those prices included shipping from China.

The total for everything would be about $200, plus backup battery.  I think I got my battery for about $65, shipped.  If I made a bunch of circuit boards, the price might drop by about $30.  I also designed the board to be able to use plain Shottky diodes instead of the 'perfect' diodes.  That would save about $14 per board, but that doesn't seem like a lot of extra money given the total parts cost.

The cheapest way possible to replicate all this would be: no LCD, only 1 output voltage, Shottky diodes instead of perfect diodes.  That would cut about $80 from the total. 

The cost of assembly is free if you do it yourself.  Some of the parts are pretty fine pitch though, so it really helps to have a fine-tip soldering iron and a stereo microscope.  Other people use toaster ovens to solder the surface mount parts and they claim it works great.  I have not tried that yet.  Maybe someday.

And there you have it: a power supply that costs a bit more than the server & disks that it powers.  But you can't put a price tag on fun.

Next up: Firmware Updates

It will be worth it in the end.