AVR-Chat

--- In AVR-Chat@yahoogroups.com, tom@k... wrote:
> I know just enough about this stuff to be dangerous, so please bear 
with me if 
> my question is laughably misplaced.
> 
> I would like a circuit designed for an LED candle. I'll be 
producing about 100 
> of them, possibly many more, more, for my haunted house. 

Circuit Cellar had an article on exactly this a year or so ago.  It 
was an actors group that needed candles for their plays.

I'll hunt around - I have them all in PDF.

Dean.

I know just enough about this stuff to be dangerous, so please bear with me if 
my question is laughably misplaced.

I would like a circuit designed for an LED candle. I'll be producing about 100 
of them, possibly many more, more, for my haunted house. Requirements:

- Flickers realistically
- Works off standard 9v batteries (or 6v battery packs if necessary) for at 
least 30 hours
- On-off switch
- Costs no more than $12 (and preferably less) to build total, including 
populated circuit board & LED(s). In my fevered imagination, I hope that the 
Atmel processors have pretty much all you need except for a couple of 
transistors, resistors, and an external switch
- LED doesn't have to be exact candle color (I can supply colored cellophane or 
whatever it it's a white LED)

And ideally but not necessarily:
- Fits without the power source in a candle
- Would have an option to plug many of them into a chandelier and power from a 
single source
- Uses a bright LED
- Has some sort of user adjustability for auto-off for power saving, and/or 
randomness setting, and/or flicker speed

Would love to know if this is even close to doable in my price range, how much 
you'd charge to design it, and where I should go to get it manufactured. Feel 
free to contact me offline or to jeer at me publically.

Thanks!

Tom Campbell

>
>- Costs no more than $12 (and preferably less) to build total, including 
>populated circuit board & LED(s). In my fevered imagination, I hope that the 
>Atmel processors have pretty much all you need except for a couple of 
>transistors, resistors, and an external switch

What are you budgeting in for design, or does that have to amortize in with the $12?

You can look at Toaster oven SMD production to keep your costs low. 
I would think a panel of 10 boards would be easy to fit. 

An AVR 2343 with some sort of PN generator code, and a simple driver for the LED would work.

Power consumption will mostly depend on the LED(s) and their operating current.

You may know that C Crane sells an electronic candle that appears
well designed, but is a bit expensive:

http://www.ccrane.com/electric_candle_in_home_lighting.asp

Here at Magic Labs we've had a fair amount of experience developing
LED lighting tricks for our conjure wands, but have so far not made
a flickering candle display.
In general, the major expense of these kinds of items will be in batteries,
 and ease/robustness of battery replacement.

However, for a one-time use, you should easy shot.

Ken Holt

At 09:33 PM 3/18/2004 -0000, you wrote:

>--- In AVR-Chat@yahoogroups.com, tom@k... wrote:
>> I know just enough about this stuff to be dangerous, so please bear 
>with me if 
>> my question is laughably misplaced.
>> 
>> I would like a circuit designed for an LED candle. I'll be 
>producing about 100 
>> of them, possibly many more, more, for my haunted house. 
>
>Circuit Cellar had an article on exactly this a year or so ago.  It 
>was an actors group that needed candles for their plays.
>
>I'll hunt around - I have them all in PDF.
>
>Dean.
>
>
>
>
> 
>Yahoo! Groups Links
>
>
>
> 
>
>

I think this should quite doable within a $12 BOM budget if not 
significantly below that.  If a standard LED is bright enough, you 
can drive the LED directly (assuming a 20 mA drain - less with 
flickering) so no need for a drive transistor. Internal oscillator so 
no xtal/caps.  I think you could run at 3V off 2 AA cells and mount 
the battery holder in-line on the pc board for a skinny "candle" 
format.  A length of white PVC pipe for the candle body and some sort 
of translucent diffuser at the top.  switch at the bottom the PCB.   
I'd probably use an 8 pin PIC rather than Atmel, just for cheapness 
sake. you should be able to get a gang of boards made for fairly 
cheap assuming a 6"x 1/2" format though you might have to sneak it by 
the board house.

Phil

--- In AVR-Chat@yahoogroups.com, tom@k... wrote:
> I know just enough about this stuff to be dangerous, so please bear 
with me if 
> my question is laughably misplaced.
> 
> I would like a circuit designed for an LED candle. I'll be 
producing about 100 
> of them, possibly many more, more, for my haunted house. 
Requirements:
> 
> - Flickers realistically
> - Works off standard 9v batteries (or 6v battery packs if 
necessary) for at 
> least 30 hours
> - On-off switch
> - Costs no more than $12 (and preferably less) to build total, 
including 
> populated circuit board & LED(s). In my fevered imagination, I hope 
that the 
> Atmel processors have pretty much all you need except for a couple 
of 
> transistors, resistors, and an external switch
> - LED doesn't have to be exact candle color (I can supply colored 
cellophane or 
> whatever it it's a white LED)
> 
> And ideally but not necessarily:
> - Fits without the power source in a candle
> - Would have an option to plug many of them into a chandelier and 
power from a 
> single source
> - Uses a bright LED
> - Has some sort of user adjustability for auto-off for power 
saving, and/or 
> randomness setting, and/or flicker speed
> 
> Would love to know if this is even close to doable in my price 
range, how much 
> you'd charge to design it, and where I should go to get it 
manufactured. Feel 

> free to contact me offline or to jeer at me publically.
> 
> Thanks!
> 
> Tom Campbell

Tom,

	I do this type of design work although normally at higher costs
than what you are looking for.

	I suggest you use an incandescent lamp instead of an LED if you
are looking for the best effects.  A simple random voltage generator
circuit with two or three voltage levels should do a good job.

	Try calling Chicago Miniature Lamp Company http://www.chml.com/
to see if you can get someone to help you find a lamp with a nice look.
The original "fireflies" on the Pirates of the Caribbean ride at
Disneyland used one of their bulbs and sockets.

	Run the lamp well below the rated voltage to get a nice warm
flame color.

	I have worked with products that were so realistic that I swear
they were actual flames (at a distance) but I was told they were not.
I'm still not sure if I believe them.

Barry

-----Original Message-----
From: tom@kobo.com [mailto:tom@kobo.com] 
Sent: Thursday, March 18, 2004 12:36 PM
Subject: [AVR-Chat] RFP - can someone design an LED candle for me?

I know just enough about this stuff to be dangerous, so please bear with
me if 
my question is laughably misplaced.

I would like a circuit designed for an LED candle. I'll be producing
about 100 
of them, possibly many more, more, for my haunted house. Requirements:

- Flickers realistically
- Works off standard 9v batteries (or 6v battery packs if necessary) for
at 
least 30 hours
- On-off switch
- Costs no more than $12 (and preferably less) to build total, including

populated circuit board & LED(s). In my fevered imagination, I hope that
the 
Atmel processors have pretty much all you need except for a couple of 
transistors, resistors, and an external switch
- LED doesn't have to be exact candle color (I can supply colored
cellophane or 
whatever it it's a white LED)

And ideally but not necessarily:
- Fits without the power source in a candle
- Would have an option to plug many of them into a chandelier and power
from a 
single source
- Uses a bright LED
- Has some sort of user adjustability for auto-off for power saving,
and/or 
randomness setting, and/or flicker speed

Would love to know if this is even close to doable in my price range,
how much 
you'd charge to design it, and where I should go to get it manufactured.
Feel 
free to contact me offline or to jeer at me publically.

Thanks!

Tom Campbell


 
Yahoo! Groups Links

>
>        I have worked with products that were so realistic that I swear
>they were actual flames (at a distance) but I was told they were not.
>I'm still not sure if I believe them.

Coding in a strange attractor might give more realistic flicker. 
I think that flame height and intensity is probably a strange attractor. Similar to water dripping. It's not random, nor regular.

Yes, although I'm not an expert on candle flicker strange attractor
algorithms, intuitively I believe you are correct.

You might want to join the Yahoo Group: Show-Control

It's a surprisingly professional group with many of the members involved
with theme park, movie, stage, and other entertainment technologies.

I'm sure that several people there will have some good suggestions for
you since many of them have worked with this sort of thing.

I've been on that list for a very long time and have seen people talk
about stuff very similar to what you are looking for.

Barry

-----Original Message-----
From: David VanHorn [mailto:dvanhorn@cedar.net] 
Sent: Wednesday, March 24, 2004 1:30 PM
Subject: RE: [AVR-Chat] RFP - can someone design an LED candle for me?

>
>        I have worked with products that were so realistic that I swear
>they were actual flames (at a distance) but I was told they were not.
>I'm still not sure if I believe them.

Coding in a strange attractor might give more realistic flicker. 
I think that flame height and intensity is probably a strange attractor.
Similar to water dripping. It's not random, nor regular.

 
Yahoo! Groups Links

Have you tried Googling for, say, battery candles flicker halloween?
I turned up this device:

http://www.bpesolutions.com/lghtefx.html#anchor615436

Which looks to be what you want.

Regards,
   JJ

On Thursday, Mar 18, 2004, at 15:36 US/Eastern, tom@kobo.com wrote:

> I know just enough about this stuff to be dangerous, so please bear  
> with me if
> my question is laughably misplaced.
>
> I would like a circuit designed for an LED candle. I'll be producing  
> about 100
> of them, possibly many more, more, for my haunted house. Requirements:
>
> - Flickers realistically
> - Works off standard 9v batteries (or 6v battery packs if necessary)  
> for at
> least 30 hours
> - On-off switch
> - Costs no more than $12 (and preferably less) to build total,  
> including
> populated circuit board & LED(s). In my fevered imagination, I hope  
> that the
> Atmel processors have pretty much all you need except for a couple of
> transistors, resistors, and an external switch
> - LED doesn't have to be exact candle color (I can supply colored  
> cellophane or
> whatever it it's a white LED)
>
> And ideally but not necessarily:
> - Fits without the power source in a candle
> - Would have an option to plug many of them into a chandelier and  
> power from a
> single source
> - Uses a bright LED
> - Has some sort of user adjustability for auto-off for power saving,  
> and/or
> randomness setting, and/or flicker speed
>
> Would love to know if this is even close to doable in my price range,  
> how much
> you'd charge to design it, and where I should go to get it  
> manufactured. Feel
> free to contact me offline or to jeer at me publically.
>
> Thanks!
>
> Tom Campbell
>
>
>
>
>
> ------------------------ Yahoo! Groups Sponsor  
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> Upgrade to 128-bit SSL Security!
> http://us.click.yahoo.com/LPJzrA/yjVHAA/TtwFAA/dN_tlB/TM
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>
>
> Yahoo! Groups Links
>
>
>
>
>

Again, I should mention, I've seen very simple systems that use two or
three levels of brightness and switch between those two or three states.
The effect seems very acceptable for most applications I would think.

Don't over complicate things.

Mainly, I think the color is important and that's why I like
incandescent lights since, by their very nature, generate light from a
hot wire which is close in color to a real flame.

You could even use some kind of smoked filter or slotted gobo that would
surround the bulb and turn on a small motor thus creating your effect.

Why make things harder than they need be?

-----Original Message-----
From: David VanHorn [mailto:dvanhorn@cedar.net] 
Sent: Wednesday, March 24, 2004 1:30 PM
Subject: RE: [AVR-Chat] RFP - can someone design an LED candle for me?

>
>        I have worked with products that were so realistic that I swear
>they were actual flames (at a distance) but I was told they were not.
>I'm still not sure if I believe them.

Coding in a strange attractor might give more realistic flicker. 
I think that flame height and intensity is probably a strange attractor.
Similar to water dripping. It's not random, nor regular.

 
Yahoo! Groups Links

David VanHorn wrote:
>>        I have worked with products that were so realistic that I
>> swear they were actual flames (at a distance) but I was told they
>> were not. I'm still not sure if I believe them.
>
> Coding in a strange attractor might give more realistic flicker.
> I think that flame height and intensity is probably a strange
> attractor. Similar to water dripping. It's not random, nor regular.


What I would do is just put together a real candle and a photo-sensor as a
LDR or even a photo-transistor and ADC the light changes from the candle.
After one minute of recording, even with a 4 bits ADC @ 10sps, you would
have enough information to store inside any microcontroller to repeat the
"real thing" flickering.

Of course that to have a good "real flickering" the experiment should be
done in am ambient that produces air movement and causes flickering.


---
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The electronic candles advertised at C. Crane claim to flicker sometimes
as if an occasional breeze had blown them.
I would suggest using an orange and yellow LED, driven by 2 different
generators, for a warm color and lively feel.  Stay away from incandescent
lights and filtering/baffling unless battery life is of no consequence -
moderate
brightness at moderate current is your primary goal.

Ken



At 05:02 PM 3/24/2004 -0800, you wrote:

>Again, I should mention, I've seen very simple systems that use two or
>three levels of brightness and switch between those two or three states.
>The effect seems very acceptable for most applications I would think.
>
>Don't over complicate things.
>
>Mainly, I think the color is important and that's why I like
>incandescent lights since, by their very nature, generate light from a
>hot wire which is close in color to a real flame.
>
>You could even use some kind of smoked filter or slotted gobo that would
>surround the bulb and turn on a small motor thus creating your effect.
>
>Why make things harder than they need be?
>
>
>-----Original Message-----
>From: David VanHorn [mailto:dvanhorn@cedar.net] 
>Sent: Wednesday, March 24, 2004 1:30 PM
>Subject: RE: [AVR-Chat] RFP - can someone design an LED candle for me?
>
>>
>>        I have worked with products that were so realistic that I swear
>>they were actual flames (at a distance) but I was told they were not.
>>I'm still not sure if I believe them.
>
>Coding in a strange attractor might give more realistic flicker. 
>I think that flame height and intensity is probably a strange attractor.
>Similar to water dripping. It's not random, nor regular.
>
> 
>Yahoo! Groups Links
>
>
>
> 
>
>
>
>
>
> 
>Yahoo! Groups Links
>
>
>
> 
>
>