51 * and Super Red: <a href="https://www.mouser.com/Search/ProductDetail.aspx?R=LS_R976-NR-1virtualkey62510000virtualkey720-LSR976-NR-1" target="_blank">720-LSR976-NR-1</a>).
52 * These are $.10 each in single quantities and the price goes down to about
53 * five and a half cents each in quantities of 100. If you decide to use chip
54 * LEDs instead of regular 3mm LEDs with leads, be sure to get some extras,
55 * because you will likely loose one or two.
56 *
57 * @image latex ChipPhoto.jpg "Photo of a typical chip LED" width=3in
58 * @image html ChipPhoto.jpg "Photo of a typical chip LED"
59 * @image latex ChipPackageOutline.png "Outline drawing of a typical chip LED" width=4.5in
60 * @image html ChipPackageOutline-thumb.png "Outline drawing of a typical chip LED"
61 *
62 * These devices come on a tape carrier. This is something normally meant to
63 * go in a robot feeding device that places the chips on circuit boards in
64 * robotic factory. To handle these devices by hand you will need to make a
65 * tool to hold them. I made a tool from a standard round toothpick. I used
66 * a razor saw to cut one of the end points off, sanded cut flat and applied a
67 * dab of <a href="http://www.micromark.com/detail-tack-2-oz-applicator-bottle,9712.html" target="_blank">Detail Tack</a>
68 * (available from <a href="http://www.micromark.com" target="_blank">Micro-Mark</a> for $7.95).
69 * This stuff dries clear and remains tacky (sticky). This lets you pick up
70 * the chips from their tape carrier and hold them in place as you re-flow the
71 * solder to secure them to the circuit board.
72 *
73 * @image latex SignalChipLEDInCarrier.jpg "Signal Chip LED In Carrier" width=3in
74 * @image html SignalChipLEDInCarrier-thumb.jpg "Signal Chip LED In Carrier"
75 * @image latex ChipTape.png "Chip Tape specs (page 13 of the data sheet)" width=4.5in
76 * @image html ChipTape-thumb.png "Chip Tape specs (page 13 of the data sheet)"
77 *
78 * You will also need a supply of wire wrap wire in a number of colors (this
79 * is available from <a href="http://www.digikey.com/product-search/en?pv77=223&FV=fff40019%2Cfff8006f%2Cfffc0028%2C1c001d&k=wire+wrap+wire&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25" target="_blank">DigiKey</a>),
80 * a supply of cut off resistor leads (or really any small solid bare wired
81 * cut into pieces about 1/2 to 3/4 inches long), and a piece of Strip-board
82 * two foil strips wide (.2 inches / 5mm) that is long enough to make little
83 * circuit boards for your targets -- you will need 6 holes for 3 color
84 * targets, 4 holes for 2 color targets, and 2 holes for single color targets.
85 * I also used a block of foam as a work surface, since it let me push the
86 * resistor leads into it.
87 *
88 * The first step is to remove some of the foil. One side is the common side
89 * (cathode end) and the other is for one-of connections (anode). The common
90 * / cathode is connected with a resistor lead that will be soldered to the
91 * brass tube the signal targets will be mounted to. The anode side will be
92 * connected with wire wrap wire, one per chip and color coded (I used green,
93 * yellow, and red for the upper head and blue, white, and black for the lower
94 * head). Once the foil bits have been removed, strip and feed the wire wrap
95 * wire on one side and push the resistor lead through a hole on the other
96 * side and then solder the wires. Be sure to spread a thin layer of solder