Below is a list of everything needed to buy if building from scratch. Don't let the $126 electronics bill scare you; there are a number of ways to save by scrounging and foregoing some cosmetic items. Aside from the Stoplight, the largest costs are the arduino and the Ethernet shield. Obviously if you have either of these items already, this project will cost considerably less (-$30 and -$44.44 ). The two enclosures are not strictly needed, particularly if you are going to stuff everything into a stop light (-$17.46 ). Any 9 volt power supply that can power the arduino can work. There is no need to buy this expensive one if you have one laying around (-$16.68 ). And finally, the ribbon cable (-$3.22 ) can be replaced by any 6 conductor cable or even just 6 wires, and probably doesn't need to be 4 feet depending on where you put the arduino and the power circuit.
You will need the following tools:
|4-||1K resistor||-- 4 X $0.06 = $0.24|
|1-||ethernet shield||-- $44.44|
|1-||arduino enclosure||-- $13.33 (optional)|
|4-||NPN Transistors 2N3904||-- 4 X $0.02 = $0.08|
|4-||Diodes 1N4004||-- 4 X $0.06 = $0.24|
|6-||break off headers from 32 pin strip||-- $0.66 (Optional, and a strip of 36 is 30 more than needed for this project)|
|1-||9 pin ribbon cable||-- 4 X $0.64 = $2.56 (4 feet, strip off 3 extra conductors and trim to size)|
|1-||3 X 2 row break off headers from 10 X 2 strip||-- $0.65 (7 more than needed, break of 3 columns)|
|1-||9 volt power supply||-- $14.30 (any 9 volt power supply should work)|
|1-||power cord for 9v power supply||-- $2.38 (the power supply I ordered didn't come with a cord!)|
|1-||screw terminal block with 6 positions||-- $1.00|
|1-||2x3 socket for ribbon cable||-- $0.66|
|1-||protoboard and enclosure (BusBoard KIT-1593L-BK)||-- $9.13|
|4-||9 volt relays (fujitsu lz-9HE)||-- 4 X $1.85 = $7.40|
|4-||1 Kohm resistors||-- 4 $0.04 = $0.24|
total = $126.83
For testing and hacking the following may be desirable, but are strictly optional:
You can order all the mouser items from this project list, or start with that list and subtract anything you don't need. Mouser apparently didn't like all the traffic going right to their shopping card and deleted this project without notice. I'll be updating with actual part numbers later. If you are starting from scratch, make sure you add supplies like solder and wire. As of this writing, mouser does not carry the circuit breaker or stop lights.
Stop lights can found on ebay or on the side of the road after a really good storm*.
* Not really, but you can find them on ebay.