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

Flicker algorithm help
Started by ●January 18, 2006
Reply by ●January 18, 20062006-01-18
"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 meto build a camp-fire> simulator. > > I already have a home-built control box and slave units for switchingpracticals. The control box> contains a ATmega32 and each of the slaves contains an Atmega8 with anopto-isolated solid state> relay. They use a multi-drop RS 485 comms network so that any number ofslaves can be connected to> one master. > > Does anyone out there have a good algorithm to simulate the flickering ofa camp-fire, or will a> simple pseudo-random sequence be sufficient? > > -- > John BCircuit 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
Reply by ●January 18, 20062006-01-18
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. > > BobThanks Bob. I'll have a look at their archive. -- John B
Reply by ●January 18, 20062006-01-18
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/>
Reply by ●January 18, 20062006-01-18
"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 wantme> > 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 numberof> > slaves can be connected to > > > one master. > > > > > > Does anyone out there have a good algorithm to simulate the flickeringof> > 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 candleson> > stage. I don't have a link but the article did talk about how to makethe> > flicker convincing. You would probably want the same algorithm for acamp> > fire. > > > > Bob > > Thanks Bob. I'll have a look at their archive. > > -- > John Bthis 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
Reply by ●January 18, 20062006-01-18
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.
Reply by ●January 18, 20062006-01-18
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). > BobHi 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
Reply by ●January 18, 20062006-01-18
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
Reply by ●January 19, 20062006-01-19
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.htmThanks 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
Reply by ●January 21, 20062006-01-21
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
