There are two major circuits
for the Hand of Fate: the
transmitter and receiver. The
modules used for these two
circuits are shown in Figure 9.
The transmitter is the simpler
of the two circuits. In it, there are
the following modules: power;
microphone; and IR LED. While
the pink color-coded input
microphone module (i21) accepts
either voice or sound/music input,
the green color-coded output IR
LED module (o7) converts the
microphone’s audio into light
waves. These light waves are then
received and decoded by the pink
color-coded light sensor module
(i13) that has been switched into
“light” mode on the receiver. The
complete receiver circuit consists
of five modules: power; light sensor; speaker; light wire;
As previously noted, the light sensor receives the IR LED
light waves and converts them into electrical pulses. These
pulses are output through the green color-coded speaker
module (o22) as sound.
We can further “piggyback” on these pulses with the
green color-coded light wire output module (o16) and the
similarly green color-coded servo module (o11).
In the case of the light wire module, we can wrap the
electroluminescent (EL) wire around the candy dish for a
pulsing green/blue glow. Likewise, the servo module uses
its “turn” mode for moving with the pulses.
You will need a couple of extra supplies like those in
Figure 10 for completing the Hand of Fate project. A latex
glove (or any other flexible glove) and a craft stick (or a
piece of your finest home plastic cutlery, like a “spork”).
Attach the craft stick to the screw hub of the servo module.
Insert the stick assembly into a finger of choice in the glove.
Now, lay the glove on the candy, wrap the candy dish with
the EL wire, and secretly hide the entire receiver circuit
beside the candy dish.
Carefully align the IR LED from the transmitter circuit
with the light sensor of the receiver. In a darkened room,
you should be able to separate the two circuits by a
distance of two feet. Now, speak into the microphone and
watch the Hand of Fate spring into life with an
accompanying sound and light show (Figure 11). TIP: It
helps to speak very closely to the microphone!
That’s it. Your Halloween is ready for ghosts and
goblins. Finally, to get you in the goblin mood, here’s a joke
for you: What kinds of streets do ghosts live on? Dead
ends! SV Figure 11. "Would you like a candy?” asks the Hand of Fate.
Figure 10. A "spork" on a servo moves a Hand of Fate finger.
SERVO 09.2015 47
Figure 9. The Hand of Fate requires two
littleBits circuits: the transmitter (upper)
and receiver (lower).