360° LEDs ( 16) available at superbrightleds.com
TIP 120 transistors ( 2)
Solderless breadboard and/or solder-type
Patterned fabric or silk-screen your own
Polyester fiberfill plush stuffing
Arduino board with power connector
12V or adjustable AC power adapter
Toggle switch (optional)
Epoxy or hot glue
Iron and ironing board
Hand-sewing needle and sewing pins
Hot glue gun if using hot glue
Computer with Arduino IDE
USB A-B cable
The breadboard and Arduino.
the perfect feature for this: pulse width modulation
(PWM). PWM can make LEDs, which are binary,
appear dimmer by pulsing them on and off, with
varying time ratios, faster than the human eye can
detect. I could use this to produce the analog sine-wave-like throbbing glow that I wanted.
The PWM signal controls the glow, but the Arduino
can only output up to 5V, which isn’t high enough
to power these super-bright LEDs. I had planned
to power the Arduino with a 12V AC adapter, so
150 Make: Volume 11
I designed the circuit to drive the LEDs from the
same source. I used 2 TIP 120 transistors to amplify
the signal to each half of the meat tray, 4 steaks
each. This pumps the circuit’s full 12V through 2
parallel sets of 2 LEDs ( 2 steaks, 4 LEDs) in series,
which works out to 3V per LED.
3. Add the LEDs.
For each steak, I made an LED insert with 2 LEDs
wired in series and neatly twisted. I spaced the LEDs
about 4" apart, so that they would each light up an
even half of the steak without being too close to the
edges. I made the lead wires really long, and I knew
they would be exposed, so I chose red and white
wire to match my plush.
After wiring up the circuit and soldering and
testing the LEDs, I finally assembled the steaks. It’s
important to make sure all your LEDs are functioning
properly first; it’s no fun to debug a sewn-together
toy. Since electronics with fabrics could be a fire
hazard, I covered the LED leads in epoxy (hot glue
works, too) to prevent a potentially dangerous short.
I positioned each double-LED wire inside a steak,
and filled around it with polyester filling. I left the
LEDs plugged in, so I could see how the light diffused
and adjust them accordingly. When I got them how
I wanted, I stitched up the bottom openings by
hand, and arranged them together on a tray.
4. Bask in the glow.
Each half of the tray ( 4 steaks) glows in alternation
with the other. The pattern is subtle and soothing,
the way a good nightlight should be. They’re soft,
but not very cuddly, as they remain tethered to their
circuit board. In the future I could embed smaller
circuit boards inside each steak to make a portable,
more snuggly version. I’ve also been thinking of
making a larger version for throw pillows, or a smaller
version with catnip instead of electronics. These
steaks have been great conversation starters in the
classroom and online, and I hope they inspire people
to learn about the politics of our food industry.
For a full schematic of the circuit, the microcontroller code, and the pattern for the steak silkscreen,
Rebecca Stern of Brooklyn, N. Y., is an artist, technologist,
and recent graduate from Parsons School of Design, where
she studied design and technology. sternlab.org