On 26/09/2020 15:56, jlarkin@highlandsniptechnology.com wrote:> On Sat, 26 Sep 2020 08:54:01 +0100, Piglet <erichpwagner@hotmail.com> > wrote: > >> On 25/09/2020 18:36, John Larkin wrote: >>> Given that this is an electronic design forum, we should design >>> something. I could start. Maybe some others can suggest circuits. >>> >> >> I already started - didn't you see my design? >> >> piglet > > Sorry, missed that one. I'd delete the EMI filter, except with a > standard dimmer as the starting point, it's free already. > > What about ramping down the value of Rt over time? Some variation on > one of my circuits? NTC thermistor? > > Maybe the entire circuit could be one NTC thermistor, one of those > inrush limiter things. > > >Yes, I think Tabby (or someone) suggested an NTC already. piglet
Slow fade-in circuit
Started by ●September 23, 2020
Reply by ●September 26, 20202020-09-26
Reply by ●September 26, 20202020-09-26
On Sat, 26 Sep 2020 17:11:54 +0100, Piglet <erichpwagner@hotmail.com> wrote:>On 26/09/2020 15:56, jlarkin@highlandsniptechnology.com wrote: >> On Sat, 26 Sep 2020 08:54:01 +0100, Piglet <erichpwagner@hotmail.com> >> wrote: >> >>> On 25/09/2020 18:36, John Larkin wrote: >>>> Given that this is an electronic design forum, we should design >>>> something. I could start. Maybe some others can suggest circuits. >>>> >>> >>> I already started - didn't you see my design? >>> >>> piglet >> >> Sorry, missed that one. I'd delete the EMI filter, except with a >> standard dimmer as the starting point, it's free already. >> >> What about ramping down the value of Rt over time? Some variation on >> one of my circuits? NTC thermistor? >> >> Maybe the entire circuit could be one NTC thermistor, one of those >> inrush limiter things. >> >> >> > >Yes, I think Tabby (or someone) suggested an NTC already. > >pigletMaybe heat sink it to a chunk of aluminum or two to slow down the turn-on? -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●September 26, 20202020-09-26
On Saturday, 26 September 2020 17:37:43 UTC+1, jla...@highlandsniptechnology.com wrote:> On Sat, 26 Sep 2020 17:11:54 +0100, Piglet <erichpwagner@hotmail.com> > wrote: > >On 26/09/2020 15:56, jlarkin@highlandsniptechnology.com wrote: > >> On Sat, 26 Sep 2020 08:54:01 +0100, Piglet <erichpwagner@hotmail.com> > >> wrote: > >>> On 25/09/2020 18:36, John Larkin wrote:> >>>> Given that this is an electronic design forum, we should design > >>>> something. I could start. Maybe some others can suggest circuits. > >>>> > >>> > >>> I already started - didn't you see my design? > >>> > >>> piglet > >> > >> Sorry, missed that one. I'd delete the EMI filter, except with a > >> standard dimmer as the starting point, it's free already. > >> > >> What about ramping down the value of Rt over time? Some variation on > >> one of my circuits? NTC thermistor? > >> > >> Maybe the entire circuit could be one NTC thermistor, one of those > >> inrush limiter things. > >> > >> > >> > > > >Yes, I think Tabby (or someone) suggested an NTC already. > > > >piglet > > Maybe heat sink it to a chunk of aluminum or two to slow down the > turn-on?With 20w of load a biggish one or 2 may be slow enough as is. Heatsinking it would require great thermal contact to be effective in slowing interior heat-up, most THs aren't a good shape for that. Laser slice them? :) You might be able to slow it further with a series cap. It takes the LED closer to the point where it dims, ie lower mains v, and Xc + Rth is going to be larger at any time during warm up. And if you really must you could slow it yet again with a PTC Thermistor across the bulb. There are so many ways it can be done. And Ricky is getting snipey again. NT
Reply by ●September 26, 20202020-09-26
On Sat, 26 Sep 2020 11:33:10 -0700 (PDT), Tabby <tabbypurr@gmail.com> wrote:>On Saturday, 26 September 2020 17:37:43 UTC+1, jla...@highlandsniptechnology.com wrote: >> On Sat, 26 Sep 2020 17:11:54 +0100, Piglet <erichpwagner@hotmail.com> >> wrote: >> >On 26/09/2020 15:56, jlarkin@highlandsniptechnology.com wrote: >> >> On Sat, 26 Sep 2020 08:54:01 +0100, Piglet <erichpwagner@hotmail.com> >> >> wrote: >> >>> On 25/09/2020 18:36, John Larkin wrote: > >> >>>> Given that this is an electronic design forum, we should design >> >>>> something. I could start. Maybe some others can suggest circuits. >> >>>> >> >>> >> >>> I already started - didn't you see my design? >> >>> >> >>> piglet >> >> >> >> Sorry, missed that one. I'd delete the EMI filter, except with a >> >> standard dimmer as the starting point, it's free already. >> >> >> >> What about ramping down the value of Rt over time? Some variation on >> >> one of my circuits? NTC thermistor? >> >> >> >> Maybe the entire circuit could be one NTC thermistor, one of those >> >> inrush limiter things. >> >> >> >> >> >> >> > >> >Yes, I think Tabby (or someone) suggested an NTC already. >> > >> >piglet >> >> Maybe heat sink it to a chunk of aluminum or two to slow down the >> turn-on? > >With 20w of load a biggish one or 2 may be slow enough as is. Heatsinking it would require great thermal contact to be effective in slowing interior heat-up, most THs aren't a good shape for that. Laser slice them? :)My wild guess is that a bit of heat sinking would slow it down. One NTC would sure be simple, but dramatic home theatre lighting may have crucial timing requirements.> >You might be able to slow it further with a series cap. It takes the LED closer to the point where it dims, ie lower mains v, and Xc + Rth is going to be larger at any time during warm up. And if you really must you could slow it yet again with a PTC Thermistor across the bulb.NTC-PTC voltage divider. Interesting.> >There are so many ways it can be done. And Ricky is getting snipey again.Again?> > >NT-- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●September 26, 20202020-09-26
lørdag den 26. september 2020 kl. 04.25.53 UTC+2 skrev jla...@highlandsniptechnology.com:> On Fri, 25 Sep 2020 17:29:21 -0700 (PDT), "rhor...@gmail.com" > <rhorerles@gmail.com> wrote: > > >On Friday, September 25, 2020 at 4:56:32 PM UTC-5, John Larkin wrote: > > > >> Do you feel like building a circuit? It could be done with 5 discrete > >> parts, or possibly 3. > > > >Yes, of course! I am having a little trouble imagining only 5 components, let alone 3, but I am game to look at anything. > > > >I did find a nice, small buck converter module that is only 7mm x 4.5mm with up to 450V input and 300ma output. It only requires 13 external components, all of which can be 1206 SMDs except for a small inductor. This makes a trailing edge MOSFET based dimmer using a 555 practical. It's $2.24, but I can handle that. > > Guess nobody wants to play. As usual. > > One of these might work: > > https://www.dropbox.com/s/616xu5p4z1bw2yb/LED_Soft-Start.JPG?raw=1 > > The lower one starts at half brightness, because of the mosfet > substrate diode. Upper one probably doesn't need R2 if you use a > protected-gate fet. > > I don't have time to Spice these, but either should work. > > There are some variants, like an RC and a source follower maybe. > > https://www.dropbox.com/s/g3kaaaauft986b9/LED_Soft_Follower.JPG?raw=1 >https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP4001/document_id/2012/ with a cap on the dim input
Reply by ●September 26, 20202020-09-26
On Sat, 26 Sep 2020 14:12:30 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>l�rdag den 26. september 2020 kl. 04.25.53 UTC+2 skrev jla...@highlandsniptechnology.com: >> On Fri, 25 Sep 2020 17:29:21 -0700 (PDT), "rhor...@gmail.com" >> <rhorerles@gmail.com> wrote: >> >> >On Friday, September 25, 2020 at 4:56:32 PM UTC-5, John Larkin wrote: >> > >> >> Do you feel like building a circuit? It could be done with 5 discrete >> >> parts, or possibly 3. >> > >> >Yes, of course! I am having a little trouble imagining only 5 components, let alone 3, but I am game to look at anything. >> > >> >I did find a nice, small buck converter module that is only 7mm x 4.5mm with up to 450V input and 300ma output. It only requires 13 external components, all of which can be 1206 SMDs except for a small inductor. This makes a trailing edge MOSFET based dimmer using a 555 practical. It's $2.24, but I can handle that. >> >> Guess nobody wants to play. As usual. >> >> One of these might work: >> >> https://www.dropbox.com/s/616xu5p4z1bw2yb/LED_Soft-Start.JPG?raw=1 >> >> The lower one starts at half brightness, because of the mosfet >> substrate diode. Upper one probably doesn't need R2 if you use a >> protected-gate fet. >> >> I don't have time to Spice these, but either should work. >> >> There are some variants, like an RC and a source follower maybe. >> >> https://www.dropbox.com/s/g3kaaaauft986b9/LED_Soft_Follower.JPG?raw=1 >> > >https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP4001/document_id/2012/ > >with a cap on the dim inputThe data sheet prohibits me from copying or printing it. OK, deal. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●September 26, 20202020-09-26
jlarkin@highlandsniptechnology.com wrote:>>https://www.monolithicpower.com/en/documentview/productdocument/index/v >>ersion/2/document_type/Datasheet/lang/en/sku/MP4001/document_id/2012/ >> >>with a cap on the dim input > > The data sheet prohibits me from copying or printing it. OK, deal.They put it on the web, so they intend for it to be copied. Besides, you are just posting the link, so you are innocent.
Reply by ●September 26, 20202020-09-26
On Saturday, September 26, 2020 at 2:56:43 AM UTC-5, piglet wrote:> Inventive fersureYes, it is surely that. The thought of a DC solution never dawned on me. Does anyone have a schematic of a typical LED bulb? If they have any AC components, this might not work, but otherwise, it should. It definitely will work with an incandescent bulb and definitely not with a fluoresent, I expect.> but the mosfet is going to dissipate a few watts for a few seconds so will need some heatsinking.Yeah, probbably, but not much.
Reply by ●September 26, 20202020-09-26
On Saturday, September 26, 2020 at 9:56:55 AM UTC-5, jla...@highlandsniptechnology.com wrote:> Sorry, missed that one. I'd delete the EMI filter, except with a > standard dimmer as the starting point, it's free already.Well, I do have several standard dimmers that I just replaced with wifi dimmers. Free is always nice. OTOH, I dislike hanging components off in the air. Unless it is a very simple mod, I would rather print my own custom boards. I guess I am kind of anal that way.> What about ramping down the value of Rt over time? Some variation on > one of my circuits? NTC thermistor? > > Maybe the entire circuit could be one NTC thermistor, one of those > inrush limiter things.Hmm. Unless temperature control is the entire purpose of the device, I dislike temperature dependent solutions. Again, maybe I am just anal that way, but environment can cause a lot of variability, especially with low temperature solutions, and high temperature solutions bring their own set of problems. Please understand I am not trying to be contrary, here. The more I think about it, the more I like the idea of a simple DC solution. It's not only unicorn free, it is elegant and very reliable. It also completely eliminates the question of triggering and timing. *IF* it works.> Science teaches us to doubt.And doubt teaches us how to do science.
Reply by ●September 26, 20202020-09-26
On Saturday, September 26, 2020 at 3:20:20 PM UTC-5, jla...@highlandsniptechnology.com wrote:> NTC would sure be simple, but dramatic home theatre lighting may have > crucial timing requirements.Uh-uh. This is just overhead lighting in a home movie theater. 'No drama, at all. The idea is simply to be kind to dark-accustomed eyes at the end of a show. Bright ights going up suddenly can actually be a bit painful. Allowing the pupils time to contract is much more comfortable.
