This page has 2 parts. The first is a description of different flicker circuits, including some videos of the different flicker circuits in a jack o' lantern for comparison. The second is a how-to for taking an LED tea light, replacing the LED with an Ultrabright LED, and the watch battery with AA batteries. If you want to go straight to the Hack click here, the description and videos follow.
I think flickering candlelight is the best for spooky, indirect lighting, but no way am I going to have candles in a haunt. I have been searching for LED candle flicker circuits. Below are videos for several different LED Flicker methods (plus a video of a real candle). Use the videos to help select which flicker is for you. Below the videos is additional information about the different circuits, including parts lists, that you may want to check before choosing, and links to other circuits I have not tried yet. I will probably build some more later, but for now this is enough.
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Campfire Flicker by Fred Miller |
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Firelight Flicker by snovotill (one circuit uses a 390k resistor, the other uses a 18k resistor) |
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Spookyfire by spookyblue |
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LED Tea Light Candles from Global Light |
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LED Tea Light Candle with Otaku's HackOtaku's Flicker |
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Real candle |
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Snovotill with 2400 mcd Red LED, and a 15k resistor in place of the 390k resistor |
Snovotill with 2 60,000 mcd Red LEDs, and a 15k resistor in place of the 390k resistor |
Spookyfire with 7 flashing LEDs |
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2 LED Tea Lights (from Global Light) |
Fred Miller campfire flicker |
Real Candle |
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| LED Tea Light from Global Light with Otaku's Hack reusing the old flame as the diffuser and a 10mm 60,000mcd LED. | LED Tea Light from Globe Light as it comes out of the box. This video compares the tea light before Otaku's hack. |
Firelight Flicker (snovotill)
All part but the 4585 and LED from allelectronics, the 4584 and LED from jameco
| 4013 (IC dual flip-flop) | $ 0.35 |
| 4584 (schmidt trigger) | $ 0.39 |
| 1N4148 | $ 0.07 |
| 100 PF RADIAL CERAMIC CAPACITOR (note: I do not use this with the 18k resistor) | $ 0.06 |
| 047MFD CAPACITOR | $ 0.15 |
| 0.1MFD RADIAL MYLAR CAPACITOR | $ 0.17 |
| 18K OHM 1/2 WATT | $ 0.05 |
| 18K OHM 1/2 WATT (note: the original snovotill circuit used a 390k OHM resister, I like the flicker provided by the 18k better) | $ 0.05 |
| 330 OHM 1/2 WATT | $ 0.05 |
| 9V BATTERY SNAP | $ 0.33 |
| LED,RED,660NM,T-1 3/4 | $ 0.16 |
| total (w/o battery) | $ 1.83 |
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There is currently some question about the 18k resistor, some have suggested a 1 meg. I have not had a chance to verify this. |
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Note that I don't use he 100 PF capacitor in the circuit with the 18k resistor. |
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Additionally it was suggested by snovotill to replace the resistor for the 200Hz oscillator with a potentiometer, which can be used to adjust the flicker between a flicker and a shimmer. I did this and found 15k to provide a good flicker (see the mystery flicker above). |
Campfire Flicker (Fred Miller)
All parts from jameco
| LM555CN,TIMER,DIP-8 | $ 0.39 |
| 74164 | $ 0.59 |
| 7486 | $ 1.39 |
| 78L05 | $ 0.27 |
| CAP,AXIAL,100uF | $ 0.22 |
| CAP,MYLAR,2.2uF | $ 0.92 |
| CAP,AXIAL,10uF | $ 0.15 |
| 3.3K OHM (2) | $ 0.01 x 2 = $0.02 |
| 1.0K OHM | $ 0.01 |
| 150 OHM | $ 0.01 |
| LED, RED, 660NM, T-1 3/4 | $ 0.16 |
| BAT HOLDER,PARALLEL,4"AA" | $ 0.89 |
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total(w/o battery) |
$ 5.02 |
The following details were contributed by 'Engineer', the moderator for the Electrics and Electronics Forum on the Halloween-L Forum.
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You can "fine tune" the rate by tinkering with the
value of the resistor between pins 6 and 7 of the 555.
Large changes in rate are made by
changing the value of the capacitor at pin 2. |
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Further, the original circuit takes an output
only off of pin 6 of the 74x164. Pins 3, 4, and 5 are unused in the original
circuit. If you put an LED on each of them, they will appear to "flicker"
differently from the first one and from each other. |
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As I mentioned before, you could use two pins
(4 and 6, for example), with an orange LED on one and a yellow on the other.
Put those two LEDs "nose to nose" and enjoy a different kind of "candle
flame" effect because of the two colors. Use pins 3 and 5 for second
"candle". |
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With the 555 running at a much slower rate
(larger capacitor), and pairs (in series) instead of single LEDs on the pins
out (3, 4, 5, 6) you can have your own version of "cave eyes"--without
a microprocessor! Compare to: |
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It isn't difficult to add an optodiac and a triac to the output(s) and apply the flicker effect to AC light bulbs. I've done this several times with old "junk" chandelier fixtures of 4, 5, and 6 bulbs. The effect is tremendous and can be very convincing. |
Spookyfire (Spookyblue)
All parts from jameco
| LED,RED,DIF,BLINK,3Hz,T1-3/4 (quantity 7) | $ 0.45 x 7 = $ 3.15 |
| 9V BATTERY SNAP | $ 0.33 |
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total |
$ 3.48 |
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As suggested on spooky blues site, you can add non-blinking LEDs. |
Led Tea Lights
I found some at Walgreen's of all places for $3.99, so I bought 2 of them because I was dying to see how they looked. There are also available at Michaels, Jo-Anne Fabrics around Halloween time, and online from several sources.
Other Flicker Circuits
Several new links from 'Engineer' over at the Halloween-L forum, thanx!
flicker from shaunathan
ALF from Phantasmechanics
Gaslight on a budget
from Phantasmechanics (need an example of fluorescent starter in here.
This is not LED).
http://wolfstone.halloweenhost.com/TechBase/flktch_FlickerTechniques.html#Kilowatt
http://wolfstone.halloweenhost.com/TechBase/flktch_FlickerTechniques.html#ETEC
http://wolfstone.halloweenhost.com/TechBase/flktch_FlickerTechniques.html#4069
http://wolfstone.halloweenhost.com/TechBase/flktch_FlickerTechniques.html#UJT
http://www.srkconsulting.com/candles/howto.html
If you have any additional circuits to try, please contact me heresjohnny@cfl.rr.com.