AB
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D
EF
C
Fig. A: Glue together a wooden lattice. Fig. B: Mount the
lattice to the front of the fan. Fig. C: Cut fabric into sharp
flame shapes. The bigger the fan, the bigger the flames.
Fig. D: Glue the fabric flames to the lattice.
Fig. E: Schematic diagram for the entire circuit, including
LEDs and fan. Fig F: Solder the LEDs together in series
with the resistor, or just twist the connections together
if you don’t feel like soldering.
MATERIALS AND TOOLS
Photography by Ed Troxell, William Gurstelle (B)
Fan, 12V The build shown here uses a computer
fan, but larger “squirrel cage” fans also work.
The more air the fan moves, the larger and more
realistic the flames; an 18 CFM fan will simulate
small fires, and a 60 CFM fan can simulate
larger ones.
12V battery or power supply
Ultrabright LEDs ( 4) in red, yellow, or orange
These LEDs produce 5,000 to 10,000 milli-candelas (mcd) of light. Many online retailers
sell them, including Amazon, Parts Express,
and Solarbotics.
Resistor, 200Ω
Hookup wire, 22 gauge
Silk or silk-like fabric, red and yellow, 1 sq. ft. each
The fabric must be light and sheer.
Fast-drying glue
Tape
Machine screws, #8-32× 1" ( 4)
Nuts, #8-32 ( 10)
Wood strip, ¼"×
1", about a 2' length
Wood strips,
7" or
2" wide, about 4" long ( 2)
Hardware cloth, a piece about 3"× 10"
Small saw
Drill and t" bit
Wire cutters to cut hardware cloth
1. Prepare the fan.
First, fabricate a lattice out of the wood strips, using
fast-drying glue. Figure A shows one way to build
the lattice. You may need to improvise based on the
dimensions and characteristics of the fan you use.
Drill holes in the lattice frame to match your fan’s
mounting holes, then secure the lattice to the fan
using machine screws and nuts (Figure B).
2. Create the silk flames.
Cut the red and yellow fabric into flame shapes
(Figure C). The more powerful your fan (i.e., the
higher its CFM rating), the longer the pieces can be.
Glue or tape the fabric flames to the lattice (Figure D).
3. Light the flame.
The schematic diagram (Figure E) shows how to
wire the LEDs and the 200Ω resistor in series. You
can solder the connections (Figure F) or just twist
them. Figure G shows how to derive the resistor
value, assuming LEDs with a forward voltage (
usually denoted VF in specifications) of 2V to 4V, and a
normal current draw of 20 to 30 milliamps (mA).
Recall that the longer of the LED’s 2 legs is the
positive leg. Wire the 4 LEDs, positive to negative,
as shown in Figures E and G.
141 Make:
