Post by thread:Mains lighting control

Hi Whats the best way of controling the brightness of mains lights? I saw a lamp a while back that consisted of a frosted perspex tube with two coloured mains lamps in it. They were then faded in and out to produce various coloured lighting in the room. I liked the idea but I thought I could do better with a PIC and make it user controllable (such as speed of change and pattern). I was thinking of triac control but I have never had to do this in the past. Can someone suggest some code or control method that would be appropriate. Cheers Tim Kerby ------------------------------------------------------------------ Personal Web Pages: http://web.ukonline.co.uk/members/tim.kerby/ Email: spam_OUTtim.kerbyTakeThisOuTukonline.co.uk ------------------------------------------------------------------

Tim Phase angle control is the easyest way to control the volume of a light (incandessent) if you need to use flouressent then consider the HF ballast from phillips they take a 0-10v signal same as many commercial dimers. A consideration with phase angle control is the ammount of noise radiated and conducted this needs to be controled with capacitive and inductive filters. Low voltage lamps were described in a recent mchip seminar using pwm and a single FET these make a simalar ammount of 'noise' but due to the switching frequency it is simpler to filter. Cheers Steve.....

I am involved with our church's annual Singing Xmas Tree, where we have an choir put on a concert in a 6 level tree shaped pyramid. We use Xmas tree lights in 4 colors and some special channels as well, all on dimmers. Commercial dimmers all seem to have that 30 volt turn on where you can't dim to or start from '0', because of the diac diode built in to most dimmers. I built a 555 ckt a few years ago, that starts its time period each ac zero crossover and then C/R times from 0 to 8.33333ms (1/2 of each 60 cycle) and then triggers a 25 amp triac. The problem is we now want to remote the control pots and I now need dc control rather than R/C time constant control as we want to run the controls ~200 ft away from the triacs/power boards. The pic seems like a good vehicle for this. One other consideration, I don't mind the concept of running analog wires/dc voltage for each control if it is much simpler, but it seems to me, I could run RS422 signals as well on two wires. Rather than re-inventing the wheel (fun but takes time), can any of you help me. Surely this has been done many times before - theater lighting etc. I have no problem with the electronics, making PC boards etc. but don't (yet) have much pic experience. Tks for your time. Mike Montaigne {Quote hidden}>---------- >From: XYGAX[SMTP:.....XYGAXKILLspam@spam@AOL.COM] >Sent: Monday, January 12, 1998 4:46 PM >To: PICLISTKILLspamMITVMA.MIT.EDU >Subject: Re: Mains lighting control > >Tim >Phase angle control is the easyest way to control the volume of a light >(incandessent) if you need to use flouressent then consider the HF ballast >from phillips they take a 0-10v signal same as many commercial dimers. > >A consideration with phase angle control is the ammount of noise radiated and >conducted this needs to be controled with capacitive and inductive filters. > >Low voltage lamps were described in a recent mchip seminar using pwm and a >single FET these make a simalar ammount of 'noise' but due to the switching >frequency it is simpler to filter. > >Cheers Steve..... >

Montaigne, Mike <.....PICLISTKILLspam.....MITVMA.MIT.EDU> wrote: > I am involved with our church's annual Singing Xmas Tree, where we > have an choir put on a concert in a 6 level tree shaped pyramid. > We use Xmas tree lights in 4 colors and some special channels as > well, all on dimmers. .... we now want to remote the control pots > and I now need dc control rather than R/C time constant control as > we want to run the controls ~200 ft away from the triacs/power > boards. .... it seems to me, I could run RS422 signals as well on > two wires. Rather than re-inventing the wheel (fun but takes > time), can any of you help me. Surely this has been done many times > before - theater lighting etc. Mike: Yes, it's been done before; take a look at the DMX512 mini-FAQ at: http://waapa.cowan.edu.au/lx/dmx-faq.htm -Andy === Andrew Warren - EraseMEfastfwdspam_OUTTakeThisOuTix.netcom.com === Fast Forward Engineering - Vista, California === http://www.geocities.com/SiliconValley/2499

Tks Andy, I printed that out. Question: Simple light dimmers are C/R time from '0' crossover to trigger triac. Theater (analog) dimmers are 0-10V control & 0-10V ramp into comparator to time from '0' xover. Even if controlled by DMX or other serial link, still electronically noisy because of A.C turn-on. Why not (using micro) always start on '0' crossover and leave out 1/2 cycles. The more 1/2 cycles you leave out (alternate odd and even so load is balanced), the dimmer the light. Would this work? I've never seen it, but I may be re-inventing the wheel again. Comments? Mike {Quote hidden}>---------- >From: Andrew Warren[SMTP:fastfwdspam_OUTIX.NETCOM.COM] >Sent: Wednesday, January 14, 1998 5:45 AM >To: @spam@PICLISTKILLspamMITVMA.MIT.EDU >Subject: Re: Mains lighting control > >Montaigne, Mike <KILLspamPICLISTKILLspamMITVMA.MIT.EDU> wrote: > >> I am involved with our church's annual Singing Xmas Tree, where we >> have an choir put on a concert in a 6 level tree shaped pyramid. >> We use Xmas tree lights in 4 colors and some special channels as >> well, all on dimmers. .... we now want to remote the control pots >> and I now need dc control rather than R/C time constant control as >> we want to run the controls ~200 ft away from the triacs/power >> boards. .... it seems to me, I could run RS422 signals as well on >> two wires. Rather than re-inventing the wheel (fun but takes >> time), can any of you help me. Surely this has been done many times >> before - theater lighting etc. > >Mike: > >Yes, it's been done before; take a look at the DMX512 mini-FAQ at: > > http://waapa.cowan.edu.au/lx/dmx-faq.htm > >-Andy > >=== Andrew Warren - RemoveMEfastfwdTakeThisOuTix.netcom.com >=== Fast Forward Engineering - Vista, California >=== http://www.geocities.com/SiliconValley/2499 >

Regarding lamp dimming by including only selected full half-cycles, I believe you'll get a lot of flicker on the lamp. This is especially the case if you want a large number of levels. Our Shoebox dimmer (http://www.dovesystems.com) maps the 256 levels of DMX to 33,333 possible turn-on times in each half cycle. If you want ten lamp levels (and don't care about relative lamp intensity or DC component), you could select to send 1 to 10 half-cycles every 83mS, resulting in a flicker rate of only 12 Hz. This would be quite visible. Harold On Fri, 16 Jan 1998 16:13:55 -0500 "Montaigne, Mike" <spamBeGonemontaignemspamBeGoneAECL.CA> writes: {Quote hidden}>Tks Andy, I printed that out. >Question: >Simple light dimmers are C/R time from '0' crossover to trigger triac. >Theater (analog) dimmers are 0-10V control & 0-10V ramp into >comparator >to time from '0' xover. >Even if controlled by DMX or other serial link, still electronically >noisy because of A.C turn-on. >Why not (using micro) always start on '0' crossover and leave out 1/2 >cycles. >The more 1/2 cycles you leave out (alternate odd and even so load is >balanced), the dimmer the light. >Would this work? I've never seen it, but I may be re-inventing the >wheel again. >Comments? >Mike > >>---------- >>From: Andrew Warren[SMTP:TakeThisOuTfastfwdEraseMEspam_OUTIX.NETCOM.COM] >>Sent: Wednesday, January 14, 1998 5:45 AM >>To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU >>Subject: Re: Mains lighting control >> >>Montaigne, Mike <PICLISTEraseME.....MITVMA.MIT.EDU> wrote: >> >>> I am involved with our church's annual Singing Xmas Tree, where we >>> have an choir put on a concert in a 6 level tree shaped pyramid. >>> We use Xmas tree lights in 4 colors and some special channels as >>> well, all on dimmers. .... we now want to remote the control pots >>> and I now need dc control rather than R/C time constant control as >>> we want to run the controls ~200 ft away from the triacs/power >>> boards. .... it seems to me, I could run RS422 signals as well on >>> two wires. Rather than re-inventing the wheel (fun but takes >>> time), can any of you help me. Surely this has been done many times >>> before - theater lighting etc. >> >>Mike: >> >>Yes, it's been done before; take a look at the DMX512 mini-FAQ at: >> >> http://waapa.cowan.edu.au/lx/dmx-faq.htm >> >>-Andy >> >>=== Andrew Warren - EraseMEfastfwdix.netcom.com >>=== Fast Forward Engineering - Vista, California >>=== http://www.geocities.com/SiliconValley/2499 >> >