On Wednesday, September 23, 2020 at 9:10:11 AM UTC-5, bitrex wrote:> Wow, what a pain in the ass. Guy said nothing about ceiling fans in the > original post.Imagine showing up looking for free work and barking> orders simultaneously. Wanna bark orders at least have the decency to > pay someone for the privilege. > > IOW get a grip, pal.
Slow fade-in circuit
Started by ●September 23, 2020
Reply by ●September 25, 20202020-09-25
Reply by ●September 25, 20202020-09-25
On Wednesday, September 23, 2020 at 9:10:11 AM UTC-5, bitrex wrote:> Wow, what a pain in the ass. Guy said nothing about ceiling fans in the > original post.No, but I did in the second post, and I apologized for not going into more detail.> Imagine showing up looking for free work and barking orders simultaneously.I did not bark any orders. I just mentioned you did not bother to read what I wrote, which is tru
Reply by ●September 25, 20202020-09-25
On Wednesday, September 23, 2020 at 6:57:34 PM UTC-5, palli...@gmail.com wrote:> rhor...@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. > > > ** 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? I used plenty of them back when I was in college, but that was 40 years ago.> 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.htmA trailing edge dimmer can be used with CFL bulbs, yes, which leading edge dimmers normally cannot. 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. I could use either one, although the 555 would need to be replaced with a passive solution, I think. It is the voltage control that has me a bit sytmied. A simple voltage divider is not a very good solution, since 130V at 20ma is 2.6 watts, whihc is going to get pretty hot in a small enclosure. Even when half-wave rectified, we are looking at 1.3 watts, unless I use some sort of switching solution.
Reply by ●September 25, 20202020-09-25
On Thursday, September 24, 2020 at 8:44:08 AM UTC-5, George Herold wrote:> Maybe hack one of the commercial triac AC dimmers? I get a ton > of hits for DIY triac dimmer. (lots with Arduino input.) > I didn't look at the details. > > George H.All of them I have seen with Arduino / Raspberry Pi inputs are PWM. That means something like a 555, which in turn means a low voltage DC supply. 'Possible, but a bit tricky given the space constraints.
Reply by ●September 25, 20202020-09-25
On Thursday, September 24, 2020 at 7:24:18 AM UTC-5, amdx wrote:> These show some promise, the size seems good, it has the 0 to 10 volt > control. I have now idea what the impedance of > > the 0 to 10 volt control is, so not sure how easy it would be to control > with an RC. Price is right. > > Not sure how it reacts to applying AC with the control held at zero. > > Might need a big resistor or see if these can be modified for 12V operation > > > https://www.1000bulbs.com/category/25-36-volt-hardwire-constant-current-led-drivers/ > 12v-36v unit > > https://www.1000bulbs.com/product/209386/HAT-10032.html > Here's a 12V unit, but it's a little longer, 4.25" x 1.5". > > > https://www.1000bulbs.com/product/100980/LEDF-ACA12V12H10M.html > > Mikek > > > -- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirusNo, those are all LED drivers. There are a number of inexpensive fade-up solutions for low voltage DC LED strips. I need a solution for 120VAC bulbs.
Reply by ●September 25, 20202020-09-25
On Thursday, September 24, 2020 at 9:58:50 AM UTC-5, bitrex wrote:> OP said he wants a circuit considerably smaller than a matchbox.That's right. There is already a WiFi fan control and light switch up in the vell housing, so there isn't a whole lot of room.> I think the clearances required for 110VAC operation and the voltage > ratings of the components you'll need to build a trailing-edge dimmer, > say, are going to make that a problem if it all has to fit on a single > board.'Not at all. The trailing edge dimmer circuit in te provided example has only 30 components. I can fit a lot more than that on a board less than 50mm on a side.> Why the circuit MUST fit inside the bell-housing of a ceiling fan isIt must fit inside the bell housing because it has to be downstream of the switch. The switch - a wifi / Google Home controlled fan and light switch is in the bell housing. Running wires from the switch to the outside of the light housing and back is not a very good idea.> unclear if this is a one-off personal application, sounds more like > someone trying to integrate something for sale.No, I wasn't considering this as a salable item. I don't think it has enough sales potential to make it practical to produce commercially. I just want it for the two ceiling fans in my theater.> Would recommend hiring an engineer in that case.I am an engineer. 'Not a EE, but I am an engineer, and this is certainly not beyond my capabilities.
Reply by ●September 25, 20202020-09-25
On Thursday, September 24, 2020 at 10:35:28 AM UTC-5, Ricketty C wrote:> A 120 VAC circuit does not require any special clearances. That would be for isolating high voltage and low voltage circuits. This entire design can be treated as a high voltage circuit.Correct. Dimmers of up to 1000watts can easily fit in a case the size of a brownie.> > It has to go in the housing of the fan so it isn't stuck someplace even more crowded like the wall switch box.That said, if a commercial product would do the job, but not fit in a match box (as if that were remotely likely) it would be very reasonable to add a box next to the fan mounting box which could then house a commercial circuit more easily.> > But it does seem reasonable to simply add a wall dimmer switch in place of the toggle switch. But maybe the lights are being brought up automatically by the "theater" system rather than manually switched on. The automatic effect would be nice though. > > -- > > Rick C. > > -- Get 1,000 miles of free Supercharging > -- Tesla referral code - https://ts.la/richard11209
Reply by ●September 25, 20202020-09-25
On Thursday, September 24, 2020 at 10:35:28 AM UTC-5, Ricketty C wrote:> A 120 VAC circuit does not require any special clearances. That would be for isolating high voltage and low voltage circuits. This entire design can be treated as a high voltage circuit.Correct. A dimmer capable of handling up to 1000 watts can easily fit in a case smaller than a brownie.> It has to go in the housing of the fan so it isn't stuck someplace even more crowded like the wall switch box.Well, in this case, it is more a matter of needing to go inline between the switch lead and the light lead, both of which are in the bell housing.>That said, if a commercial product would do the job, but not fit in a match box (as if that were remotely likely) it would be very reasonable to add a box next to the fan mounting box which could then house a commercial circuit more easily.That's possible, but not bery convenient. It's not the main issue, however.> But it does seem reasonable to simply add a wall dimmer switch in place of the toggle switch.Not when there is no toggle switch. The fan and light are entirely controlled wirelessly by the module in the bell housing. There is no switch box, at all.>But maybe the lights are being brought up automatically by the "theater" system rather than manually switched on.Actually, they are being brought up by a Google Home Mini.>The automatic effect would be nice though.Manual fading would not be practical, really.
Reply by ●September 25, 20202020-09-25
On Thursday, September 24, 2020 at 8:45:33 AM UTC-5, Ricketty C wrote:> Even dimmable LED bulbs don't always respond well to the standard triac/SCR type dimmers.Yeah, I know that, too. This doesn't have to be ultra-fancy or ultra-smooth.> I bought an LED ceiling light along with a dimmer which was listed on the LED package as "compatible". It works very badly, requiring the handle to move > half it's range before the LED comes on at all, then the brightness is irregular with movement of the control and even varies a bit while the handle is still.I would expect it to be stable once the light control reaches 100%. Until then, it needn't be perfectly stable, as long as it doesn't actually flash on and off.> In your application this will mostly not be an issue although you may see some flickering of the light as it dims.You mean as it fades up? It won't be fading down, and with two light fixtures (two fans), some flicker will be less noticeable.
Reply by ●September 25, 20202020-09-25
On 23/09/2020 5:08 am, rhor...@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. >If a conventional triac based domestic dimmer will drive your lights then you could try adapting it a bit like this: <https://www.dropbox.com/s/8ll9n5wjnzl21wh/dimmer_fade_up.pdf?dl=0> I haven't built this and it is only conceptual so some experimentation will be needed. It works like this: The diac/triac firing phase angle is determined by the time it takes for the voltage across CT to reach the diac trigger voltage, typically 20-30V. By robbing RT current from charging CT the add-on circuit can extend the firing delay without having to change RT. Finally because the voltage across CT is limited to 30V or so then the add-on parts can all be jelly bean low power devices. In more detail: D1-D4 can be 1N4148/914 etc. Q1-Q4 can be 2N3904/BC847 etc. C2 is the fade-up timing capactior probably several uF, as it charges via R4 it reduces the current sunk by Q3/Q4 to zero. R1-3, C1, and Q1-2 ensure that C2 is discharged between uses. When the circuit is live Q1 is periodically switched on and keeps the C1 Q2 base node low. Q2 then plays no part in the fade-up ramp. When the power is removed R3 and Q2 discharge C2. After drawing the schematic I realized that the E-B junction of Q2 may be overly reverse biased so a diode in series with either the base or emitter may be wise. As a start point R1-2-3-4 could all be about a megaohm, R5 about 5k, C1 about 0.1uF. D5 can be a low power 8-18V zener, as long as it is lower than the diac trigger volatge. It serves to ensure that even when Q3/4 are shunting phase timing current there is sufficient voltage to keep Q1 active. Be interested to know if it actually works! piglet
