On Friday, September 25, 2020 at 5:00:54 PM UTC-5, Jasen Betts wrote:> no. but terminals, strain-releif, and insulation will take up most of the matchbox > size leaving very little room for any active parts. those things scale > with wire-size and voltage, you have not indicated a willingness to > negotiate on those parameters.Oh, nonsense. The only thing that will carry any significant current is the output stage, which consists of either a Triac or a pair of MOSFETs. Those will be TO-220 cases sitting off the board. They probably don't even need heat sinks, given the small current they will be carrying. There is no need for any insulation other than that provided by the board itself and the plastic case. I won't use terminals. The wires will solder to the board.
Slow fade-in circuit
Started by ●September 23, 2020
Reply by ●September 25, 20202020-09-25
Reply by ●September 25, 20202020-09-25
On Friday, September 25, 2020 at 5:00:54 PM UTC-5, Jasen Betts wrote:> size leaving very little room for any active parts. those things scale > with wire-size and voltage, you have not indicated a willingness toOh, yeah. Wire size. The fixture is intended to utilize four 5 watt bulbs. That's 20 watts, or 0.167 amperes. Allowing for NEC rules, we apply a factor of 1.2, or 0.2 amperes. Even 32AWG wire can easily handle more than that, but I won't go that low. I will use 18AWG stranded wire, which can handle up tp 16 amperes (over 2000 watts) in free air.
Reply by ●September 25, 20202020-09-25
On 2020-09-26, rhor...@gmail.com <rhorerles@gmail.com> wrote:> On Friday, September 25, 2020 at 5:00:54 PM UTC-5, Jasen Betts wrote: >> size leaving very little room for any active parts. those things scale >> with wire-size and voltage, you have not indicated a willingness to > > Oh, yeah. Wire size. The fixture is intended to utilize four 5 watt bulbs. That's 20 watts, or 0.167 amperes. Allowing for NEC rules, we apply a factor of 1.2, or 0.2 amperes. Even 32AWG wire can easily handle more than that, but I won't go that low. I will use 18AWG stranded wire, which can handle up tp 16 amperes (over 2000 watts) in free air.NEC allows that only if the wire is protected by a suitable fuse or breaker. do you have a 200mA fuse in your setup that you have not told us about yet? It's only just today I found out that you had the light switch built into the fan. -- Jasen.
Reply by ●September 25, 20202020-09-25
rhor...@gmail.com wrote: -------------------------> > > > > ** So called "Dimmable LEDs" are not all the same nor dimmable > > by usual means like triac dimmers or a variac. > > Who on Earth would employ a variac these days?** It was an example of "usual means" - and they are used in circumstances where EMI free dimming is needed.> I used plenty of them back when I was in college,** I use one every day - so do most service tech.> > Most are designed to use a "trailing edge dimmer" that chops the AC wave in the reverse sense to a triac. The circuit inside the lamp uses this clue to control the LED current. > > > > See fig 1 for a schematic of such a dimmer. > > > > https://sound-au.com/project157.htm > > A trailing edge dimmer can be used with CFL bulbs,** Cos their operation is closer to tat of a variac.> It is true leading edge dimmers may not work as well as trailing edge dimmers with LED bulbs, but unless I am mistaken, I believe most consumer dimmers are leading edge dimmers, and they do work with dimmable LED bulbs well enough.** IME not, makers specifically warn TE dimmers must be used. ..... Phil
Reply by ●September 25, 20202020-09-25
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 -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●September 26, 20202020-09-26
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
Reply by ●September 26, 20202020-09-26
On 26/09/2020 03:25, jlarkin@highlandsniptechnology.com wrote:> 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 > > > > >Inventive fersure but the mosfet is going to dissipate a few watts for a few seconds so will need some heatsinking. piglet
Reply by ●September 26, 20202020-09-26
On Sat, 26 Sep 2020 08:56:37 +0100, Piglet <erichpwagner@hotmail.com> wrote:>On 26/09/2020 03:25, jlarkin@highlandsniptechnology.com wrote: >> 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 >> >> >> >> >> > >Inventive fersure but the mosfet is going to dissipate a few watts for a >few seconds so will need some heatsinking. > >pigletMaybe. As I said, I didn't have time to Spice any of those ideas. Take them as starting points. Brainstorm, please. Play. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●September 26, 20202020-09-26
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? > >pigletSorry, 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. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
Reply by ●September 26, 20202020-09-26
On 9/25/2020 6:47 PM, Ricketty C wrote:> On Friday, September 25, 2020 at 4:58:36 PM UTC-4, John S wrote: >> On 9/25/2020 1:44 PM, Ricketty C wrote: >>> On Friday, September 25, 2020 at 1:36:55 PM UTC-4, John Larkin wrote: >>>> On Tue, 22 Sep 2020 21:08:07 -0700 (PDT), "rhor...@gmail.com" >>>> <rhorerles@gmail.com> wrote: >>>> >>>>> I need a simple circuit design for a slow fade-in AC dimmer. In a dark theater, suddenly turning on the lights is a somewhat unpleasant experience. I want a simple circuit compatible with 110 volt dimmable LED lights that will slowly ramp the light output over a period of about 5 seconds or so. I have found a number of simple designs that would work for 12VDC LEDs, but none for 110VAC dimmable LED lights. >>>> >>>> Given that this is an electronic design forum, we should design >>>> something. I could start. Maybe some others can suggest circuits. >>>> >>>> How much power are the LED lights, in total? >>>> >>>> A triac dimmer typically won't see a low enough impedance when dimming >>>> some LEDs. I have one string of LED spots, with one incandescent left >>>> to make the dimmer work. >>> >>> I would design using modules. I already posted a link to two. Done and dusted! >>> >>> Since when is Larkin actually concerned about discussing electronic design other than when he intends to use it as a put down for someone? That is a truly nasty individual. >>> >>> It's no wonder that Larkin is not respected by many here. On a personal level he is the sort of person the world would be better off without. But he has a highly specialized skill in a corner of electronics design that still has some minimal demand, so the world pays him to do that. >>> >> >> You are a good contributor to the group, Ricketty, except when you're >> not. There are not that many people here that dislike Larkin. He, too, >> is a good contributor. He does not post the kind of diatribe as you have >> done. You do much better at describing projects than you do at this kind >> of attack. Please take my post as constructive criticism. > > Fine, but it's not accurate. There have been any number of posts by Larkin responding to nothing in particular by others where he talks about his disfavored few being "nasty" and other choice terms. That was why I used the term. > > It is rather un-evenhanded to call my two, short paragraphs as a "diatribe" but ignore the many ugly posts by Larkin. > > That's on you. >How many is "any number" of posts? Have you counted them? What is his ratio of "ugly" posts vs total posts? And you have not responded to my earlier post asking "How many is many? Have you taken a census?" Give us some data. That's on you.
