# Questions about flickering LEDs



## berzerkmonkey (Oct 31, 2006)

I'm looking to do some flickering candle hacks, but I have a few questions before I rush headlong into the project. I'm hoping that people who have done it might be able to shed some light here...

I'm most likely going to purchase a lot of 55,000mcd white LEDs ($30 for 100 - sheesh!) What kind of battery power should I use for the project? I know Otaku's hack (http://www.johnnyspage.com/otakuFlickerHowto/otakuHack.htm) uses four AAs, but is that too much for a single LED? Will that much power significantly reduce the life of the LED? I was thinking of using 2 AAs, which is still probably too much, but will this work for the project?

Also, what kind of battery life can I expect out of this? Will 2 AAs dry up in a couple of hours? Is that why Otaku's uses 4 AAs?

Finally, is can anyone point to a good flicker circuit? I want to wire a few LEDs together for a lantern, but I obviously don't want a constant burning light and I also don't want to pile 3-4 flickering candles in there either. I know Revenant had sketched one up at one time, but a) I can't seem to find it, and b) I can't read schematics (yet.)


----------



## gmacted (Jan 18, 2006)

You're going to need 4 AA batteries. It's not the power, it's the voltage you'll need. I don't want to get too technical, but the forward voltage drop across those LEDs is typically ~3.4V. Each AA battery will give you 1.5 V, so two AA batteries in series will only give you 3.0V. Not enough to drive the current through the LED. You'll need at least three batteries, but a four AA battery holder is standard. I'd use four AA batteries if using AA batteries.

I personally used a 9V battery and the FireLight Flicker Circuit on heresjohnny's page. Here is a link to the circuit. This project took some time, and I knew what I was doing. There's a lot of soldering involved. I built three of these circuits, and used three ultra bright LEDs.

As far as battery life. I used a 9V battery and was able to run my circuit with 3 LEDs for a couple of days continuously. I was really surprised that they lasted that long. You should get at least a day or two of running time.


----------



## berzerkmonkey (Oct 31, 2006)

Duh, you're right. I wasn't thinking about the voltage. Thanks for the clarification. 

As for the circuit you linked to, what parts are required? I understand the resistors and capacitors on the schematic, but the rest is Greek to me. Also, how much did it cost you to construct?


----------



## gmacted (Jan 18, 2006)

I'll pull all my stuff together and give you a better answer later. I built three of these circuits and I don't recall how much it cost off the top of my head.


----------



## berzerkmonkey (Oct 31, 2006)

Thanks much - I appreciate it.


----------



## berzerkmonkey (Oct 31, 2006)

ALSO: Forgot to ask this - When doing a flickering candle hack, would it be possible to do it with a 9v battery and resistor? I was looking at battery clips and you can get three 9v clips for the same price as one 4AA clip. You'd also wind up using a bit less space.

Are there any advantages to using the 4AAs over the 9V?


----------



## Otaku (Dec 3, 2004)

I use a 9 volt with my LED spotlights, which use three 10,000 mcd LEDs wired in series. I go generic with the resistor - one 150 ohm per set. I get lots of hours out of a battery. I used the 4AA pack just for hacking the tea lights. I swapped in a 10K mcd LED and just wired the battery pack without a resistor; I'm lazy. I did notice that if you don't use a resistor with a 9 volt for the tea light hack, you will lose the flicker circuit pretty quickly, followed by a blown LED. You can certainly use a 9 volt with a single LED flicker candle, just be sure to use the right resistor.


----------



## gmacted (Jan 18, 2006)

Heresjohnny has a parts list on his web site with the parts you will need. Here is the link parts list. It's the first parts list under the videos. According to that list, it costs ~$1.83 in parts. That doesn't include a circuit board an enclosure and an on/off switch. In all, you're probably looking at less than $10 per circuit. Then you have to build it. I hope you know how to solder and are good at it. It's going to take some time.


----------



## Sickie Ickie (Jun 20, 2006)

You do realize that you can use a blinking led to make all the leds blink, right?


----------



## JacksonManor (Jun 27, 2007)

Check these out...
http://www.enjoylighting.com/candle_batt.htm
I bought one of the beeswax candles at my local Bed Bath and Beyond for around $14.

I desoldered the LEDs and put them on wires for this candle...





I am currently working on some BS2 candles, but I am having a hard time getting them to look as good as the enjoy while maintaining total control.


----------



## JacksonManor (Jun 27, 2007)

Oooh these look even better (cheaper). They have 3 LEDs in them as well but I don't know if they look the same, I can only assume they do...

http://www.enjoylighting.com/votives.htm#1


----------



## JohnnyL (Aug 17, 2006)

JaksonManor - What did you use to create the candle sleeve? Looks great! Also, are the 3 LED's just flashing LED's? I'm thinking of wiring together 2 flashing LED's and 1 steady, think that would work? Do you happen to know what type of LED's those are in the candle you hacked?

I really want to create a few floor candelabras, which will have about 6-12 candles, so I'd create 6-12 clumps of 3 LED's.


----------



## Criss (Aug 9, 2007)

I found these flicker led tea candle lights in Australia at the $2 shop . We got an old candle holder put some pvc pipe as the candle and soldered all the wire to a 9 volt battery with a 470K resistor . They give a very nice effect as the leds flicker independent of each other . I found another type of tea light that did nt look as good , you could solder 2 plain led s to the unit . But they flashed in unison with each other .

These ones you just cut the led out and re solder it to some wire , resistor and battery .

Did the wax drips with a hot glue gun

Just need to hide the wires and it's ready to go beside the coffin in our church setting


----------



## pyro (Oct 7, 2006)

nice -that looks good-you could hot clue the wire on the back side that should do


----------



## JacksonManor (Jun 27, 2007)

The candle body started out as a real candle. Using a soldering iron and another candle, I hollowed out the tip and shaped it how I saw fit. Then used the iron and other candle to add drips down the "hero" candle. I had a co-worker make a mold of it and he poured me copys out of a material called pour-cast.

I put A LOT of drips down one side and less down the other while varying in between so I could rotate the candles different ways and or chop some shorter so they won't LOOK identical.

The LEDs in the enjoy Lighting candles are clear lens steady burn superbright yellow LEDs.
I don't think flashing LEDs would look good, even if you got them flashing separatly the timing would be consistant. You will want a random delay between pulses.

I have another method that looks really good but doesn't use LEDs, it uses christmas lights.

I have a tutorial here...
http://www.jacksonmanor.net/blog/?page_id=72


----------



## Criss (Aug 9, 2007)

pyro said:


> nice -that looks good-you could hot clue the wire on the back side that should do


Good idea was going to tape them but glue will be quicker

JacksonManor great job i love em , going to try do a few .

Cheers


----------



## JohnnyL (Aug 17, 2006)

Do the LED votives have a flicker circuit board?


----------



## JohnnyL (Aug 17, 2006)

Would wiring a cluster of 3 led's (two flashing, one steady) give off a decent effect? It might be easier (and brighter) than wiring the LED flickering votive candles. Would be similar to http://www.spookyblue.com/halloween/flickerlight/spookyfire/index.htm only one of the led's in the cluster would be steady.


----------



## Otaku (Dec 3, 2004)

JohnnyL,
I did that very thing with the Spookyfire design and was happy with the effect. I used about 6 flashing LEDs and one or two steady LEDs wired in parallel. I didn't use a resistor on the flashing LEDs, but you'll need one on the steady LED or it will overdrive (green LEDs aren't supposed to glow yellow and burn your finger). I may have a video of the effect - if I can find it I'll post it here.

Found the vids:

MOV03351.flv video by Otaku1031 - [email protected]@[email protected]@http://vid73.photobucket.com/player.swf?file=http://vid73.photobucket.com/albums/i231/Otaku1031/[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@i231/Otaku1031/MOV03351

MOV03453.flv video by Otaku1031 - [email protected]@[email protected]@http://vid73.photobucket.com/player.swf?file=http://vid73.photobucket.com/albums/i231/Otaku1031/[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@[email protected]@i231/Otaku1031/MOV03453

The cardboard holders were placed in urns and covered with strechy spiderweb to diffuse the light.


----------



## JohnnyL (Aug 17, 2006)

Thanks Otaku!

Does anyone know of a source for flickering LED circuit boards?


----------



## The_Caretaker (Mar 6, 2007)

One of the forums had a link to a ebay seller who had them can't seem to find them at the moment though


----------

