Slow fade-in circuit...

[Ricketty C]

On Wednesday, September 23, 2020 at 5:39:52 AM UTC-4, Miguel Giménez wrote:

El 23/09/2020 a las 6:08, rhor...@gmail.com escribió:
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.


We did that many years ago with a small microcontroller and a triac, it
worked very well. The application was sunrise/sunset simulation in a
city small-scale model.

Bet you weren\'t using LED lights. LEDs often flicker a bit when used on triac type dimmers. I\'ve read some articles about why this happens, but don\'t recall the reasons. I think it comes down to the fact that LED supplies don\'t naturally respond to changes in the AC duty cycle. So they have to measure the phase angle of the triac turn on and adjust the dimming from that. Since the full AC cycle is not presented to the supply the duty cycle is horrible.

For all practical purposes triac type dimming is deprecated for use with LEDs. Direct control via a low voltage or resistance is the recommended method. But then this is an extra wire and a low voltage extra wire which must be run separately... in other words, a PITA.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[bitrex]

On 9/24/2020 9:45 AM, Ricketty C wrote:

On Wednesday, September 23, 2020 at 4:20:28 AM UTC-4, rhor...@gmail.com wrote:
On Wednesday, September 23, 2020 at 12:39:09 AM UTC-5, whit3rd wrote:
LED fixtures that take 110VAC are all different types and designs, and while some come with dimmer
options, not all do.

I am aware, thanks. Non-dimmable bulbs do not work well with dimmers. \'Big surprise. It is easy enough to buy dimmable LED bulbs.

Even dimmable LED bulbs don\'t always respond well to the standard triac/SCR type dimmers. 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.

In your application this will mostly not be an issue although you may see some flickering of the light as it dims.


There are also different types of \"12VDC\" lamps, none of which (to my knowledge)
is a simple LED.
Many are. As a matter of fact, I just installed a 12V wifi dimmer on my 12V LED strips lining the stair step in my theater. I already have wifi control of the ceiling lights. I just need them to come up slowly when turned on. A VCO feeding a Triac / Diac pair should work, but I am unsure of details.

You could, however, operate a servo motor to lower a shade over a panel, or
rotate a polarizer, i.e. ignore the electronic range of such devices by... ignoring the electronic parts.
No, no, no. That is going off the rails. All I need is a circuit with a slowly charging capacitor that changes the duty cycle of a Triac.

Good luck with that. I believe I would use an 8 pin MCU which is aware of the line voltage as well as the phase. A problem with many dimmers is the poor response to line voltage changes, but then you won\'t be using it in a dimmed mode. The dimming will be purely transient coming up to full brightness in a few seconds.

OP said he wants a circuit considerably smaller than a matchbox.

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.

Why the circuit MUST fit inside the bell-housing of a ceiling fan is
unclear if this is a one-off personal application, sounds more like
someone trying to integrate something for sale.

Would recommend hiring an engineer in that case.

 

[Ricketty C]

On Thursday, September 24, 2020 at 10:58:50 AM UTC-4, bitrex wrote:

On 9/24/2020 9:45 AM, Ricketty C wrote:
On Wednesday, September 23, 2020 at 4:20:28 AM UTC-4, rhor...@gmail.com wrote:
On Wednesday, September 23, 2020 at 12:39:09 AM UTC-5, whit3rd wrote:
LED fixtures that take 110VAC are all different types and designs, and while some come with dimmer
options, not all do.

I am aware, thanks. Non-dimmable bulbs do not work well with dimmers. \'Big surprise. It is easy enough to buy dimmable LED bulbs.

Even dimmable LED bulbs don\'t always respond well to the standard triac/SCR type dimmers. 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.

In your application this will mostly not be an issue although you may see some flickering of the light as it dims.


There are also different types of \"12VDC\" lamps, none of which (to my knowledge)
is a simple LED.
Many are. As a matter of fact, I just installed a 12V wifi dimmer on my 12V LED strips lining the stair step in my theater. I already have wifi control of the ceiling lights. I just need them to come up slowly when turned on. A VCO feeding a Triac / Diac pair should work, but I am unsure of details.

You could, however, operate a servo motor to lower a shade over a panel, or
rotate a polarizer, i.e. ignore the electronic range of such devices by... ignoring the electronic parts.
No, no, no. That is going off the rails. All I need is a circuit with a slowly charging capacitor that changes the duty cycle of a Triac.

Good luck with that. I believe I would use an 8 pin MCU which is aware of the line voltage as well as the phase. A problem with many dimmers is the poor response to line voltage changes, but then you won\'t be using it in a dimmed mode. The dimming will be purely transient coming up to full brightness in a few seconds.


OP said he wants a circuit considerably smaller than a matchbox.

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.

Why the circuit MUST fit inside the bell-housing of a ceiling fan is
unclear if this is a one-off personal application, sounds more like
someone trying to integrate something for sale.

Would recommend hiring an engineer in that case.

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.

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

 

[bitrex]

On 9/24/2020 11:35 AM, Ricketty C wrote:

On Thursday, September 24, 2020 at 10:58:50 AM UTC-4, bitrex wrote:
On 9/24/2020 9:45 AM, Ricketty C wrote:
On Wednesday, September 23, 2020 at 4:20:28 AM UTC-4, rhor...@gmail.com wrote:
On Wednesday, September 23, 2020 at 12:39:09 AM UTC-5, whit3rd wrote:
LED fixtures that take 110VAC are all different types and designs, and while some come with dimmer
options, not all do.

I am aware, thanks. Non-dimmable bulbs do not work well with dimmers. \'Big surprise. It is easy enough to buy dimmable LED bulbs.

Even dimmable LED bulbs don\'t always respond well to the standard triac/SCR type dimmers. 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.

In your application this will mostly not be an issue although you may see some flickering of the light as it dims.


There are also different types of \"12VDC\" lamps, none of which (to my knowledge)
is a simple LED.
Many are. As a matter of fact, I just installed a 12V wifi dimmer on my 12V LED strips lining the stair step in my theater. I already have wifi control of the ceiling lights. I just need them to come up slowly when turned on. A VCO feeding a Triac / Diac pair should work, but I am unsure of details.

You could, however, operate a servo motor to lower a shade over a panel, or
rotate a polarizer, i.e. ignore the electronic range of such devices by... ignoring the electronic parts.
No, no, no. That is going off the rails. All I need is a circuit with a slowly charging capacitor that changes the duty cycle of a Triac.

Good luck with that. I believe I would use an 8 pin MCU which is aware of the line voltage as well as the phase. A problem with many dimmers is the poor response to line voltage changes, but then you won\'t be using it in a dimmed mode. The dimming will be purely transient coming up to full brightness in a few seconds.


OP said he wants a circuit considerably smaller than a matchbox.

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.

Why the circuit MUST fit inside the bell-housing of a ceiling fan is
unclear if this is a one-off personal application, sounds more like
someone trying to integrate something for sale.

Would recommend hiring an engineer in that case.

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.

Enforcing some minimum distances between hot and neutral traces and any
exposed contacts with hot and neutral on them seems like a good
idea...resistors that are going to see the full rectified line voltage
across them at some point should be rated for 350 volts

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.

It\'s a weird requirement for a one-off

 

[Ricketty C]

On Thursday, September 24, 2020 at 12:02:33 PM UTC-4, bitrex wrote:

On 9/24/2020 11:35 AM, Ricketty C wrote:
On Thursday, September 24, 2020 at 10:58:50 AM UTC-4, bitrex wrote:
On 9/24/2020 9:45 AM, Ricketty C wrote:
On Wednesday, September 23, 2020 at 4:20:28 AM UTC-4, rhor...@gmail.com wrote:
On Wednesday, September 23, 2020 at 12:39:09 AM UTC-5, whit3rd wrote:
LED fixtures that take 110VAC are all different types and designs, and while some come with dimmer
options, not all do.

I am aware, thanks. Non-dimmable bulbs do not work well with dimmers. \'Big surprise. It is easy enough to buy dimmable LED bulbs.

Even dimmable LED bulbs don\'t always respond well to the standard triac/SCR type dimmers. 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.

In your application this will mostly not be an issue although you may see some flickering of the light as it dims.


There are also different types of \"12VDC\" lamps, none of which (to my knowledge)
is a simple LED.
Many are. As a matter of fact, I just installed a 12V wifi dimmer on my 12V LED strips lining the stair step in my theater. I already have wifi control of the ceiling lights. I just need them to come up slowly when turned on. A VCO feeding a Triac / Diac pair should work, but I am unsure of details.

You could, however, operate a servo motor to lower a shade over a panel, or
rotate a polarizer, i.e. ignore the electronic range of such devices by... ignoring the electronic parts.
No, no, no. That is going off the rails. All I need is a circuit with a slowly charging capacitor that changes the duty cycle of a Triac.

Good luck with that. I believe I would use an 8 pin MCU which is aware of the line voltage as well as the phase. A problem with many dimmers is the poor response to line voltage changes, but then you won\'t be using it in a dimmed mode. The dimming will be purely transient coming up to full brightness in a few seconds.


OP said he wants a circuit considerably smaller than a matchbox.

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.

Why the circuit MUST fit inside the bell-housing of a ceiling fan is
unclear if this is a one-off personal application, sounds more like
someone trying to integrate something for sale.

Would recommend hiring an engineer in that case.

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.

Enforcing some minimum distances between hot and neutral traces and any
exposed contacts with hot and neutral on them seems like a good
idea...resistors that are going to see the full rectified line voltage
across them at some point should be rated for 350 volts

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.


It\'s a weird requirement for a one-off

What\'s weird about it??? I can see someone wanting to not blow out their theater experience by bringing up the lights abruptly. I get that.

There is a lot of home automation stuff on aliexpress, but you can never tell just what it really does. They always push the Wow! factor rather than explaining it in any detail.

The ads are SO into color! Doesn\'t matter what it does, but it has to have color!!!

--

Rick C.

-+ Get 1,000 miles of free Supercharging
-+ Tesla referral code - https://ts.la/richard11209

 

[Tabby]

On Thursday, 24 September 2020 14:54:25 UTC+1, Ricketty C wrote:

On Wednesday, September 23, 2020 at 5:39:52 AM UTC-4, Miguel Giménez wrote:
El 23/09/2020 a las 6:08, rhor...@gmail.com escribió:
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.


We did that many years ago with a small microcontroller and a triac, it
worked very well. The application was sunrise/sunset simulation in a
city small-scale model.

Bet you weren\'t using LED lights. LEDs often flicker a bit when used on triac type dimmers. I\'ve read some articles about why this happens, but don\'t recall the reasons. I think it comes down to the fact that LED supplies don\'t naturally respond to changes in the AC duty cycle. So they have to measure the phase angle of the triac turn on and adjust the dimming from that. Since the full AC cycle is not presented to the supply the duty cycle is horrible.

For all practical purposes triac type dimming is deprecated for use with LEDs. Direct control via a low voltage or resistance is the recommended method. But then this is an extra wire and a low voltage extra wire which must be run separately... in other words, a PITA.

Series capacitor makes a lot more sense than a resistance. No extra wire needed.


NT

 

[Tabby]

On Thursday, 24 September 2020 19:07:19 UTC+1, Ricketty C wrote:

On Thursday, September 24, 2020 at 12:02:33 PM UTC-4, bitrex wrote:

It\'s a weird requirement for a one-off

What\'s weird about it??? I can see someone wanting to not blow out their theater experience by bringing up the lights abruptly. I get that.

There is a lot of home automation stuff on aliexpress, but you can never tell just what it really does. They always push the Wow! factor rather than explaining it in any detail.

The ads are SO into color! Doesn\'t matter what it does, but it has to have color!!!

I forget the original requirement details. An NTC thermistor could fade up some LEDs extremely simply.


NT

 

[Ricketty C]

On Thursday, September 24, 2020 at 4:33:20 PM UTC-4, Tabby wrote:

On Thursday, 24 September 2020 14:54:25 UTC+1, Ricketty C wrote:
On Wednesday, September 23, 2020 at 5:39:52 AM UTC-4, Miguel Giménez wrote:
El 23/09/2020 a las 6:08, rhor...@gmail.com escribió:
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.


We did that many years ago with a small microcontroller and a triac, it
worked very well. The application was sunrise/sunset simulation in a
city small-scale model.

Bet you weren\'t using LED lights. LEDs often flicker a bit when used on triac type dimmers. I\'ve read some articles about why this happens, but don\'t recall the reasons. I think it comes down to the fact that LED supplies don\'t naturally respond to changes in the AC duty cycle. So they have to measure the phase angle of the triac turn on and adjust the dimming from that. Since the full AC cycle is not presented to the supply the duty cycle is horrible.

For all practical purposes triac type dimming is deprecated for use with LEDs. Direct control via a low voltage or resistance is the recommended method. But then this is an extra wire and a low voltage extra wire which must be run separately... in other words, a PITA.

Series capacitor makes a lot more sense than a resistance. No extra wire needed.


NT

Care to explain that in the context of my post? I was talking about using commercially available dimmer circuits. How are you talking of using a capacitor? You mean to dim it only on application of power? Yeah, I suppose that could work, but it requires building a circuit which is to the many issues of building a hobby circuit and adding it to a high voltage line.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[rhor...@gmail.com]

On Wednesday, September 23, 2020 at 9:53:12 AM UTC-5, Bill Sloman wrote:

It\'s rather unrealistic ambition. He wants to control ten watts or more at 110V AC - about 100mA - and wants the whole thing in a package smaller than a matchbox, and simple with it. You can get quite a lot of surface mount components into that sort of volume, but it would need some reactive components, and ones that can cope with that kind of power tend to be a bit on the bulky side.

--
Bill Sloman, Sydney
So I suppose I am dreaming when I look at this dimmer sitting in my hand that is smaller than a pack of cards and can handle 600 watts? Or the one below which handles 1000 watts AND includes WiFi?

https://www.amazon.com/DS-Wang-Module-90-250V-Automation-Intelligent/dp/B08HV6WXR6/ref=sr_1_45?crid=JOTC5FGUZFGB&dchild=1&keywords=wifi+fan+dimmer&qid=1601014148&sprefix=wifi+fan+dimmer%2Caps%2C182&sr=8-45

 

[rhor...@gmail.com]

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.

 

[rhor...@gmail.com]

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

 

[rhor...@gmail.com]

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.htm

A 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.

 

[rhor...@gmail.com]

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.

 

[rhor...@gmail.com]

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/antivirus

No, 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.

 

[rhor...@gmail.com]

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 is

It 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.

 

[rhor...@gmail.com]

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

 

[rhor...@gmail.com]

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.

 

[rhor...@gmail.com]

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.

 

[piglet]

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

 

[Martin Brown]

On 25/09/2020 07:49, rhor...@gmail.com wrote:

No, 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.

One slightly expensive solution is to swap the existing bulbs for smart
ones and control them with an app. Then you can program the on-off time
constants if you choose the right system.

Otherwise you basically want a soft start LED compatible trailing edge
dimmer that has a time constant of 5s before it allows full mains cycles
through. Your problem may well be that individual lamps do not present
*enough* load to any of the commercial dimmers to work reliably.

A friend has burnt out several 240v trailing edge LED dimmers in a
configuration that ought to work if the manufacturers were honest. The
dimmer manufacturers have agreed to replace the failing duds free of
charge which I take to be an admission of guilt.

--
Regards,
Martin Brown