38 December 2014
BUILD IT YOURSELF
By Ron Newton
This is not only a great teaching project for soldering surface-mount components,
it is also perfect for the holidays and very inexpensive. Now, you can help cultivate
interest in a budding student getting started in electronics AND take care of some
gift giving in one fell swoop.
There are two projects in this article. The first utilizes surface-mount parts with a microprocessor. It has 16 different colored LEDs that flash randomly, blink, have patterns
that run up and down and down and up, and flash
different colors. It equates to about one minute of
programming. The other project uses through-hole
components. The new rainbow LEDs used here
change colors and blink. This is about a three minute
project. (My wife actually prefers this style.) Both
versions use a small hearing aid battery. There’s a
video available in the NV Webstore if you’d like to
see these two different types in action.
This project helps to teach hand surface-mounting
and has assembly files that can be changed to make your
own patterns. Normally with my projects, I include
programming pads so you can change the programming
on the board. This one does not, however. The low
impedance on the programming pathways prevents this,
The board files were generated using ExpressPCB and
their free software ( www.expresspcb.com). These files
along with hex and assembly files for the microprocessor
are available at the article link. If you don’t want to worry
about programming, there is a complete kit available from
the NV Webstore.
Okay ... let’s get started by first discussing some
helpful tools and tricks to make your construction faster,
safer, and easier.
You won’t really need much in tools. Curved forceps
(check out Mouser 578-EROP7SA for $3.90), a small
tipped soldering tip (I use a Weller PTS8 1/64” long),
“Tacky Flux” (Chip Quik SMD 290), small solder wire (I
use Kester 0.60 mm), and solder wick .030 (Digi-Key 60-1-
5-ND). If you’re like me, a lit magnifying lens, loupe, or
head magnifier will also be of use. Check out Figure 1.
You won’t need a reflow oven for this project.
MAKE THESE UNIQUE XMAS