when I started building my 3˜4 scale B9 to start from the top down.
This is backwards of how many builders do it. Naturally the brain
was the first thing I tackled.
The usual method if lighting the brain is with flasher bulbs. However,
I had some special problems to consider. First was the fact that
incandescent bulbs generate a goodly amount of heat and my brain
box was fashioned from acrylic. The heat from bulbs would
warp or crack the plastic after some time. Second, I was concerned
that the power supply I had scrounged up for my robot may not have
adequate amperage if I used all incandescent bulbs.
use little current, and generate almost no heat, especially when
properly biased. The problem was getting them to blink in
a pleasing manner. I have included the schematic I chose to use.
It is fairly basic, and, while not random, it is very flexible.
properly done can appear random except under scrutiny.
are currently available in almost every basic color, giving you
more than a few choices. I went with a multicolor scheme. To me,
it was the most pleasing option.
The circuit was constructed of a 555 timer IC, a 4017 decade counter/divider
IC, and a handful of discreet supporting components. It was constructed
on a solderable perf board, and measures about 2 inches on a side.
The LEDs were mounted in 3 separate acrylic support rails, drilled
with evenly spaced 5mm holes to mount the 28 T1 3˜4 LEDs. The 2
side rails have ten holes each, and the front rail has eight (shorter
to accommodate the eye lights).
rails are mounted about 1˜4 inch behind the sides of the brain with
a bead of goop. The LEDs are press fit into the holes, and soldered
to a common ground buss line. Individual LEDs are addressed by the
outputs of the decade counter through rainbow ribbon cable. (I have
included a scan of the actual brain wireing, however, it did not
turn out as well as I would have liked.) The three separate sets
of LEDs are wired in parallel, so one on each side flashes at a
my scaled version could not accommodate a cam drive type device
to animate the light rods, (couldnít find a suitable size
motor) I decided to tap the first and last output lines to light
LEDs mounted in the light rods. The effect is not as spectacular
as moving light rods, but at least they are semi-functional.
Brain Light Schematic Parts List/Notes
IC1 555 timer chip
IC2 4017 decade counter chip
R1 39K ohm, 1/4watt
R2 1K ohm 1/4 watt, OR 5/10 K pot
R3 1K ohm 1/4 watt
C1 47uf, 16v electrolytic capacitor
D1-D10 T1 3/4 LEDs, any color except blue or white
D11 T1 miniature LED
NOTES: R2 can be replaced with an adjustable resistor (trimmer or
potentiometer) for a variable rate.
pattern of the display can be varied by changing the output lines
to the display. Experiment on a solderless circuit board for the
most pleasing effect.
is recommended that this (or any) circuit be tried out on a solderless
board first, so component values can be selected or changed.
reason I specify any color except blue ore white is that these kinds
of LEDs have a significantly higher forward voltage (3.2-3.7V) compared
to other kinds of LEDs. While this circuit may be able to drive
them without pull up transistors, I have not tested it for this.
circuit has been successfully tested to drive three full sets of
LEDs in parallel, for a total of 30 LEDs, flashing 3 at a time.
The datasheet on the 4017 states that it can handle up to 15Vdc,
however, I have only tested this circuit up to 12V.
outputs of the 4017 could easily be used to drive 12V lamps with
the addition of pull up transistors, however I have not included
a diagram for this.
wiring for such is left to the builder.