Hardware Reference
In-Depth Information
absolutely cheapest place to get them is from the Far East through eBay, although the quality
you get can be a bit hit and miss. here will be plenty of stockists that carry them in your
home country.
In this project you have two options when it comes to powering these strips. he irst is
where the length of strip is restricted to 12 LEDs - that is about 130mm. he second is where
you can power a strip length up to 0.7 of a meter, but more on that later. First you will look
at the 130mm option.
Before you start you will have to conigure the PiFace board by removing some of the links. his
involves removing jumpers JP4, JP5, JP6 and JP7; this disconnects the internal 5V supply
from the PiFace board's output devices and disables the relays. See Figure 11-3 for the position
of these on the PiFace board. It is important you do this before connecting anything else up.
Figure 11-3:
PiFace jumpers.
Now the LED strips come in diferent colours. Normally these are white, red, green, blue and
amber, so no doubt you will be wanting some of each. You need to cut up each strip you want to
light into smaller strips of 12 LEDs. Figure 11-4 shows you where to cut; you will need a sharp
hobby knife or better still a scalpel. Every nine LEDs there is a copper soldering area; however this
will not appear on the end of every strip of twelve lights. Not to worry - it is very easy to scrape
the green solder mask of the board with a scalpel. If you don't fancy that, you can always use the
solder areas in the middle of the strips. You will end up with eight strips all the same length, but
you might want a good mix of colours; the white ones do produce the most light however.
