On 22/01/2006 the venerable Wim Lewis etched in runes:

> 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 :-)

Thanks Wim. That looks really useful. Code is in C too so conversion to AVR should be a breeze.

-- 
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

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

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 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 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.

"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

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.

-- 
"If you want to post a followup via groups.google.com, don't use
  the broken "Reply" link at the bottom of the article.  Click on
  "show options" at the top of the article, then click on the
  "Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>

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" <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