Flicker algorithm help

I am just starting a small design for amateur theatre group. They want me to build a camp-fire
simulator.

I already have a home-built control box and slave units for switching practicals. The control box
contains a ATmega32 and each of the slaves contains an Atmega8 with an opto-isolated solid state
relay. They use a multi-drop RS 485 comms network so that any number of slaves can be connected to
one master.

Does anyone out there have a good algorithm to simulate the flickering of a camp-fire, or will a
simple pseudo-random sequence be sufficient?

-- 
John B

"John B" <spamj_baraclough@blockerzetnet.co.uk> wrote in message
news:43ce7a19$0$823$4c56ba96@master.news.zetnet.net...
> I am just starting a small design for amateur theatre group. They want me
to build a camp-fire
> simulator.
>
> I already have a home-built control box and slave units for switching
practicals. The control box
> contains a ATmega32 and each of the slaves contains an Atmega8 with an
opto-isolated solid state
> relay. They use a multi-drop RS 485 comms network so that any number of
slaves can be connected to
> one master.
>
> Does anyone out there have a good algorithm to simulate the flickering of
a camp-fire, or will a
> simple pseudo-random sequence be sufficient?
>
> -- 
> John B

Circuit Cellar had a project 2 or 3 years ago IIRC for handheld candles on
stage. I don't have a link but the article did talk about how to make the
flicker convincing. You would probably want the same algorithm for a camp
fire.

Bob

On 18/01/2006 the venerable Bob etched in runes:

> 
> "John B" <spamj_baraclough@blockerzetnet.co.uk> wrote in message
> news:43ce7a19$0$823$4c56ba96@master.news.zetnet.net...
> > I am just starting a small design for amateur theatre group. They want me
> to build a camp-fire
> > simulator.
> > 
> > I already have a home-built control box and slave units for switching
> practicals. The control box
> > contains a ATmega32 and each of the slaves contains an Atmega8 with an
> opto-isolated solid state
> > relay. They use a multi-drop RS 485 comms network so that any number of
> slaves can be connected to
> > one master.
> > 
> > Does anyone out there have a good algorithm to simulate the flickering of
> a camp-fire, or will a
> > simple pseudo-random sequence be sufficient?
> > 
> > -- 
> > John B
> 
> Circuit Cellar had a project 2 or 3 years ago IIRC for handheld candles on
> stage. I don't have a link but the article did talk about how to make the
> flicker convincing. You would probably want the same algorithm for a camp
> fire.
> 
> Bob

Thanks Bob. I'll have a look at their archive.

-- 
John B

John B wrote:
> 
... snip ...
> 
> Does anyone out there have a good algorithm to simulate the
> flickering of a camp-fire, or will a simple pseudo-random
> sequence be sufficient?

Dunno, but I believe the old fashioned method was to have a small 
motor rotate a crumpled mica tube over a light bulb.  Used in 
artificial fireplaces and the ilk.

-- 
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  the broken "Reply" link at the bottom of the article.  Click on
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  "Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>

"John B" <spamj_baraclough@blockerzetnet.co.uk> wrote in message
news:43ce8fbb$0$820$4c56ba96@master.news.zetnet.net...
> On 18/01/2006 the venerable Bob etched in runes:
>
> >
> > "John B" <spamj_baraclough@blockerzetnet.co.uk> wrote in message
> > news:43ce7a19$0$823$4c56ba96@master.news.zetnet.net...
> > > I am just starting a small design for amateur theatre group. They want
me
> > to build a camp-fire
> > > simulator.
> > >
> > > I already have a home-built control box and slave units for switching
> > practicals. The control box
> > > contains a ATmega32 and each of the slaves contains an Atmega8 with an
> > opto-isolated solid state
> > > relay. They use a multi-drop RS 485 comms network so that any number
of
> > slaves can be connected to
> > > one master.
> > >
> > > Does anyone out there have a good algorithm to simulate the flickering
of
> > a camp-fire, or will a
> > > simple pseudo-random sequence be sufficient?
> > >
> > > -- 
> > > John B
> >
> > Circuit Cellar had a project 2 or 3 years ago IIRC for handheld candles
on
> > stage. I don't have a link but the article did talk about how to make
the
> > flicker convincing. You would probably want the same algorithm for a
camp
> > fire.
> >
> > Bob
>
> Thanks Bob. I'll have a look at their archive.
>
> -- 
> John B

this might help, too:
http://wolfstone.halloweenhost.com/TechBase/flksof_SoftwareFlicker.html

several versions of a candle. One is the CC piece I was thinking of (Oct
2002).
Bob

On Wed, 18 Jan 2006 15:28:08 -0500 in comp.arch.embedded, "Chuck F. "
<cbfalconer@yahoo.com> wrote:

>John B wrote:
>> 
>... snip ...
>> 
>> Does anyone out there have a good algorithm to simulate the
>> flickering of a camp-fire, or will a simple pseudo-random
>> sequence be sufficient?
>
>Dunno, but I believe the old fashioned method was to have a small 
>motor rotate a crumpled mica tube over a light bulb.  Used in 
>artificial fireplaces and the ilk.

I've seen modern implementations that use a shredded nylon cloth,
blown upwards by a small fan, lit from beneath by a small colored
lightbulb.  Surprisingly effective.

Regards,
 
                                        -=Dave

-- 
Change is inevitable, progress is not.

On 18/01/2006 the venerable Bob etched in runes:

.
.
> 
> this might help, too:
> http://wolfstone.halloweenhost.com/TechBase/flksof_SoftwareFlicker.html
> 
> several versions of a candle. One is the CC piece I was thinking of (Oct
> 2002).
> Bob

Hi Bob. I couldn't find the article on Circuit Cellar but I have just subscribed to the electronic
edition!! That website is just what I need. Thanks.

-- 
John B

On Wed, 18 Jan 2006 09:37:27 -0800, "Bob" <SkiBoyBob@excite.com> wrote:

>
>"John B" <spamj_baraclough@blockerzetnet.co.uk> wrote in message
>news:43ce7a19$0$823$4c56ba96@master.news.zetnet.net...
>> I am just starting a small design for amateur theatre group. They want me
>to build a camp-fire
>> simulator.
>>
>> I already have a home-built control box and slave units for switching
>practicals. The control box
>> contains a ATmega32 and each of the slaves contains an Atmega8 with an
>opto-isolated solid state
>> relay. They use a multi-drop RS 485 comms network so that any number of
>slaves can be connected to
>> one master.
>>
>> Does anyone out there have a good algorithm to simulate the flickering of
>a camp-fire, or will a
>> simple pseudo-random sequence be sufficient?
>>
>> -- 
>> John B
>
>Circuit Cellar had a project 2 or 3 years ago IIRC for handheld candles on
>stage. I don't have a link but the article did talk about how to make the
>flicker convincing. You would probably want the same algorithm for a camp
>fire.

Nuts & Volts had a project on this for last October's issue. The article
itself isn't online but there is a link to the example source code. Back
issues are for sale, though, natch.

http://www.nutsvolts.com/toc_Pages/oct05toc.htm

-- 
Rich Webb   Norfolk, VA

On 19/01/2006 the venerable Rich Webb etched in runes:

.
.
.
> Nuts & Volts had a project on this for last October's issue. The article
> itself isn't online but there is a link to the example source code. Back
> issues are for sale, though, natch.
> 
> http://www.nutsvolts.com/toc_Pages/oct05toc.htm

Thanks Rich. I've got the code, but haven't looked at it yet. I suppose I'll have to translate from
BASIC to C. Hmmm, could be worse ;-)


-- 
John B

In article <43ce7a19$0$823$4c56ba96@master.news.zetnet.net>,
John B <spamj_baraclough@blockerzetnet.co.uk> wrote:
>I am just starting a small design for amateur theatre group. They want
>me to build a camp-fire simulator.
>
[...]
>
>Does anyone out there have a good algorithm to simulate the flickering
>of a camp-fire, or will a simple pseudo-random sequence be sufficient?

Here's an article with some info on simulating candle flicker.
   http://instruct1.cit.cornell.edu/courses/eceprojectsland/STUDENTPROJ/2001to2002/pc59/

The basic answer is a pseudo-random sequence with a 1-pole low pass
filter at some lowish frequency.

That URL's from my bookmarks, but I think I found it by looking through some
of the same websites people are mentioning elsewhere in this thread :-)

-- 
   Wim Lewis <wiml@hhhh.org>, Seattle, WA, USA. PGP keyID 27F772C1