We needed a fake fire for our Halloween decoration, so we decided to make our own.
This is not a new idea, we built our small fire based on this larger fire.
Step 1: Parts & Tools List
- USB Fan
The fan needs to be strong enough to keep the fabric "standing". We tried a cheap PC fan that we had lying around but it was too weak to blow the fabric reliably. You may have better luck if you have a more powerful PC fan.
- Bright LEDs
We used two red and two yellow super bright LEDs from AdaFruit.
We used 1K resistors, you can try lower. I would not go lower than 220 ohms or you will risk damaging the LEDs.
- USB Cable Extender
- 5V power supply
We used two separate power supplies: a phone charger for the USB fan and a wall adaptor for the LEDs. You may be able to use one 5V supply and a USB hub to power both.
- Scrap wires
To connect the LED, resistor and the power supply.
- Thin light white fabric
We used an old threadbare sheet. Any white thin fabric should work.
Scrap stick or dowel
To hold the fabric and LEDs over the fan.
Foam core board
Thick cardboard or wood scraps would work as a base also
To complete the illusion
We put the resistors on a breadboard, but you can just solder it, the circuit is extremely simple.
Black spray paint (optional)
We like everything except for the fabric to be black to hide it all, but the wood kindling probably already hides things quite well, so painting is optional.
- Box cutter to cut the foam board and wood stick
- Hot glue gun
- Soldering iron (optional) if you decide to solder the parts
- Multimeter (optional) to confirm polarity of the power supply
Step 2: Construction
All we're trying to do is blow the fabric upward. The simplest thing I could think of was a flat base, two pillars and a cross piece to hold the fabric and LEDs.
First cut the fabric into the fire shape and just hold it with your hand to make sure the fan is strong enough. Experiment with different "fire" lengths and shapes. Then glue the fabric on a stick and find the ideal placement. If you place the fabric too close to the fan, it will flap around too much, place it too far and it will flop down and not "stand up".
How the LED shines on the fabric affects how it looks, so bend the LEDs forward and backward to get as much of the beam on the fabric.
Once you find the optimal position, make the pillars at that height and hot glue everything.
We made two of these "fire on a stick", to give it a layered look. However, one layer might be enough
Step 3: Wiring
Wiring is straightforward, each LED should have its own current limiting resistor. We used 1K for my LEDs, you can try lower to make it brighter but probably should not go lower than 220 ohm or you will risk damaging the LED.
Flat side with the shorter lead is cathode (-)
Non-flat side with the longer lead is anode (+)
If you have a multimeter, use it to test the power polarity, otherwise, just try hooking it up and if it does not light up, reverse the + and -.
We used a header and breadboard to experiment with different LEDs and resistor values. However, this is not strictly necessary as you can just solder everything together.