Slow fade-in circuit...

[Ricketty C]

On Saturday, September 26, 2020 at 2:33:16 PM UTC-4, Tabby 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?

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.

Yes, I suggest a method of solving the problem that doesn\'t need to be spiced, is guaranteed to work out of the box and is very affordable... that\'s snipey.

Larkin doesn\'t take the time to simulate the circuits to show they really work and I\'m not going to take the time to find the guy an exact part number..

This is not a project I would want to spend significant time on designing a circuit that can have hidden risk of fire and/or shock when there are off the shelf solutions.

If you don\'t mind that sort of risk, there are off the shelf solutions on aliexpress for a song, probably cheaper than the parts to build a dimmer and won\'t limit the circuit to only dimming and at just one rate.

This conversation has dragged out for days already. I expect it will be some time longer before anyone has a circuit that might actually work. It\'s not the sort of thing I would be wanting to design a circuit for. I would want to get it done and move on to more useful endeavors. That\'s why I recommended a module.

--

Rick C.

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

 

[bitrex]

On 9/26/2020 2:33 PM, Tabby 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?

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

I think a thermistor might work with some cheapo LED bulbs but the
good-quality ones have an integrated buck converter that likely has some
undervoltage lock-out on the rectified mains input.

I think those type which are \"dimmable\" accomplish it through an
auxiliary circuit to sense if the input is chopped and hold-off the
lockout if so and translate the angle of the zero-crossing to an
appropriate set-point for the regulator.

 

[bitrex]

On 9/26/2020 8:53 PM, Ricketty C wrote:

On Saturday, September 26, 2020 at 2:33:16 PM UTC-4, Tabby 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?

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.

Yes, I suggest a method of solving the problem that doesn\'t need to be spiced, is guaranteed to work out of the box and is very affordable... that\'s snipey.

Larkin doesn\'t take the time to simulate the circuits to show they really work and I\'m not going to take the time to find the guy an exact part number.

This is not a project I would want to spend significant time on designing a circuit that can have hidden risk of fire and/or shock when there are off the shelf solutions.

If you don\'t mind that sort of risk, there are off the shelf solutions on aliexpress for a song, probably cheaper than the parts to build a dimmer and won\'t limit the circuit to only dimming and at just one rate.

This conversation has dragged out for days already. I expect it will be some time longer before anyone has a circuit that might actually work. It\'s not the sort of thing I would be wanting to design a circuit for. I would want to get it done and move on to more useful endeavors. That\'s why I recommended a module.

Clearly the answer is to build an artificially-intelligent dimmable LED
bulb that can automatically adapt itself to a wide range of standard
dimmer circuits.

I\'m only half-kidding

 

[Jan Panteltje]

On a sunny day (Sat, 26 Sep 2020 14:42:14 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
<badvmftp4m6r9vfsbvt0a7u9a28og9sm9j@4ax.com>:

>The data sheet prohibits me from copying or printing it. OK, deal.

Here is my take, untested:
http://panteltje.com/pub/triac_trigger_r_IXIMG_0540.JPG

C2 sets fade-in time.

Disadvantage: needs pulse tranasformer (10 cent upwards from China).

The UTJ circuit is from around 1966 or so,
For triggering I think most triacs are fine when triggered positive with negative voltage
across those.
No idea if it dims all LED lights, my cheap Chinese LED bulbs use a
capacitor as current limit in series with a bridge with the LEDs in it
directly on the mains, no other parts, should work.

Wave form drawings should explain.

Other disadvantage is the series resistor for the 12V,
but it basically only charges the cap, the PNP is a linear current source
to charge the cap, not many mA needed

You can replace the resistors on the PNP with a pot for brightness adjustment.

Circuit resets at each zero crossing of the mains and causes a trigger pulse
sooner (brighter) or later (dimmer) in each half cycle.

<disclaimer>

<end disclaimer>

Would a ISDN transformer work as pulse transformer ;-)?

 

[George Herold]

On Saturday, September 26, 2020 at 4:20:20 PM UTC-4, jla...@highlandsniptechnology.com wrote:

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.

That is fun!
Do NTCs, PTCs have lifetime, number of uses limits?
(I know I could search on DK... but that\'s work. :^)

George H.

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

 

[amdx]

On 9/27/2020 1:40 AM, Jan Panteltje wrote:

On a sunny day (Sat, 26 Sep 2020 14:42:14 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
badvmftp4m6r9vfsbvt0a7u9a28og9sm9j@4ax.com>:

The data sheet prohibits me from copying or printing it. OK, deal.
Here is my take, untested:
http://panteltje.com/pub/triac_trigger_r_IXIMG_0540.JPG

I see you are still stuck in your old ways.
Mikek


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[mpm]

On Wednesday, September 23, 2020 at 12:08:15 AM UTC-4,
> 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.

Can\'t you just use an Alexa (Amazon Echo) compatible light bulb and run a quick script?
10%..., 20%..., 40%..., 100%

Each bulb is addressable.

 

[Piglet]

On 27/09/2020 16:40, George Herold wrote:

On Saturday, September 26, 2020 at 4:20:20 PM UTC-4, jla...@highlandsniptechnology.com wrote:
NTC-PTC voltage divider. Interesting.
That is fun!
Do NTCs, PTCs have lifetime, number of uses limits?
(I know I could search on DK... but that\'s work. :^)

George H.

Yes, the shadow mask degaussing coil around CRT color tubes was often
fed by a PTC/NTC thermistor combo. Mostly reliable but switching on and
off repeatedly before they had reached thermal equilibrium was said to
kill them.

piglet

 

[server]

On Sun, 27 Sep 2020 17:32:27 +0100, Piglet <erichpwagner@hotmail.com>
wrote:

On 27/09/2020 16:40, George Herold wrote:
On Saturday, September 26, 2020 at 4:20:20 PM UTC-4, jla...@highlandsniptechnology.com wrote:
NTC-PTC voltage divider. Interesting.
That is fun!
Do NTCs, PTCs have lifetime, number of uses limits?
(I know I could search on DK... but that\'s work. :^)

George H.


Yes, the shadow mask degaussing coil around CRT color tubes was often
fed by a PTC/NTC thermistor combo. Mostly reliable but switching on and
off repeatedly before they had reached thermal equilibrium was said to
kill them.

piglet

Were they separated or thermally coupled?



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Tabby]

On Sunday, 27 September 2020 02:56:49 UTC+1, bitrex wrote:

I think a thermistor might work with some cheapo LED bulbs but the
good-quality ones have an integrated buck converter that likely has some
undervoltage lock-out on the rectified mains input.

why would anyone design that into an LED lamp? What for?


NT

 

[Tabby]

On Sunday, 27 September 2020 18:18:39 UTC+1, jla...@highlandsniptechnology.com wrote:

On Sun, 27 Sep 2020 17:32:27 +0100, Piglet <erichpwagner@hotmail.com
wrote:
On 27/09/2020 16:40, George Herold wrote:
On Saturday, September 26, 2020 at 4:20:20 PM UTC-4, jla...@highlandsniptechnology.com wrote:

NTC-PTC voltage divider. Interesting.
That is fun!
Do NTCs, PTCs have lifetime, number of uses limits?
(I know I could search on DK... but that\'s work. :^)

George H.


Yes, the shadow mask degaussing coil around CRT color tubes was often
fed by a PTC/NTC thermistor combo. Mostly reliable but switching on and
off repeatedly before they had reached thermal equilibrium was said to
kill them.

Life was not infinite, but a colour tv where one had failed was uncommon.
However bear in mind that TVs were generally cost sensitive machines, if you run your thermistor half as hot the metallisation does not oxidise.


> Were they separated or thermally coupled?

I\'m trying to remember. I think there were both separate -istors & then 3 legged blocks. I\'m not sure it makes much difference, the short heatup time isn\'t going to transfer significant heat from one to the other.


NT

 

[server]

On Sun, 27 Sep 2020 10:36:34 -0700 (PDT), Tabby <tabbypurr@gmail.com>
wrote:

On Sunday, 27 September 2020 02:56:49 UTC+1, bitrex wrote:

I think a thermistor might work with some cheapo LED bulbs but the
good-quality ones have an integrated buck converter that likely has some
undervoltage lock-out on the rectified mains input.

why would anyone design that into an LED lamp? What for?


NT

It\'s common for them to have a bridge rectifier and a linear IC
voltage regulator. Or even some passive-part current limiters.






--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[Piglet]

On 27/09/2020 18:18, jlarkin@highlandsniptechnology.com wrote:

On Sun, 27 Sep 2020 17:32:27 +0100, Piglet <erichpwagner@hotmail.com
wrote:

On 27/09/2020 16:40, George Herold wrote:
On Saturday, September 26, 2020 at 4:20:20 PM UTC-4, jla...@highlandsniptechnology.com wrote:
NTC-PTC voltage divider. Interesting.
That is fun!
Do NTCs, PTCs have lifetime, number of uses limits?
(I know I could search on DK... but that\'s work. :^)

George H.


Yes, the shadow mask degaussing coil around CRT color tubes was often
fed by a PTC/NTC thermistor combo. Mostly reliable but switching on and
off repeatedly before they had reached thermal equilibrium was said to
kill them.

piglet

Were they separated or thermally coupled?

Thermally coupled in one packaged three terminal module.

piglet

 

[George Herold]

On Sunday, September 27, 2020 at 1:41:11 PM UTC-4, Tabby wrote:

On Sunday, 27 September 2020 18:18:39 UTC+1, jla...@highlandsniptechnology.com wrote:
On Sun, 27 Sep 2020 17:32:27 +0100, Piglet <erichpwagner@hotmail.com
wrote:
On 27/09/2020 16:40, George Herold wrote:
On Saturday, September 26, 2020 at 4:20:20 PM UTC-4, jla...@highlandsniptechnology.com wrote:

NTC-PTC voltage divider. Interesting.
That is fun!
Do NTCs, PTCs have lifetime, number of uses limits?
(I know I could search on DK... but that\'s work. :^)

George H.


Yes, the shadow mask degaussing coil around CRT color tubes was often
fed by a PTC/NTC thermistor combo. Mostly reliable but switching on and
off repeatedly before they had reached thermal equilibrium was said to
kill them.

Life was not infinite, but a colour tv where one had failed was uncommon.
However bear in mind that TVs were generally cost sensitive machines, if you run your thermistor half as hot the metallisation does not oxidise.
OK, the OP\'s home theater is ~ a TV.

I made this thermistor pressure sensor, kinda a pirani gauge*..
but just a lm317 current source into a ~10 k NTC and measure the
voltage. It works from atm. down to ~0.1 torr.. it\'s sensitive
(on the high pressure end) to the outside (vacuum can) temperature.

George H.

*1/2 a pirani gauge bridge.

Were they separated or thermally coupled?

I\'m trying to remember. I think there were both separate -istors & then 3 legged blocks. I\'m not sure it makes much difference, the short heatup time isn\'t going to transfer significant heat from one to the other.


NT

 

[George Herold]

On Sunday, September 27, 2020 at 3:23:37 PM UTC-4, piglet wrote:

On 27/09/2020 18:18, jlarkin@highlandsniptechnology.com wrote:
On Sun, 27 Sep 2020 17:32:27 +0100, Piglet <erichpwagner@hotmail.com
wrote:

On 27/09/2020 16:40, George Herold wrote:
On Saturday, September 26, 2020 at 4:20:20 PM UTC-4, jla...@highlandsniptechnology.com wrote:
NTC-PTC voltage divider. Interesting.
That is fun!
Do NTCs, PTCs have lifetime, number of uses limits?
(I know I could search on DK... but that\'s work. :^)

George H.


Yes, the shadow mask degaussing coil around CRT color tubes was often
fed by a PTC/NTC thermistor combo. Mostly reliable but switching on and
off repeatedly before they had reached thermal equilibrium was said to
kill them.

piglet

Were they separated or thermally coupled?




Thermally coupled in one packaged three terminal module.

piglet

So I\'m guessing not made anymore.. or not for less than $1.
George h.

 

[rhor...@gmail.com]

I did some testing, and the dimmable LED bulb I used did not turn on with 64VDC, although it did pull a couple of milliamps at that voltage. That is as high a voltage as my lab power supply can produce, so I am going to order some parts to build a variable output high voltage supply, but of course they will take a few days to get here.

Meanwhile, pending testing, I am leaning toward a PWM oscillator with a voltage controlled duty cycle fed by a simple voltage integrator, pending the results of the high voltage testing. It is already clear a simple AC or DC voltage ramp is not going to work well. Pity

 

[rhor...@gmail.com]

On Sunday, September 27, 2020 at 1:40:53 AM UTC-5, Jan Panteltje wrote:

On a sunny day (Sat, 26 Sep 2020 14:42:14 -0700) it happened
jla...@highlandsniptechnology.com wrote in
badvmftp4m6r9vfsb...@4ax.com>:
The data sheet prohibits me from copying or printing it. OK, deal.
Here is my take, untested:
http://panteltje.com/pub/triac_trigger_r_IXIMG_0540.JPG

I am sorry, but I am having a very hard time making out your diagram. It is very dim, and no offense intended, but the writing is not very legible.

 

[rhor...@gmail.com]

On Sunday, September 27, 2020 at 11:25:25 AM UTC-5, mpm wrote:

On Wednesday, September 23, 2020 at 12:08:15 AM UTC-4,
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.
Can\'t you just use an Alexa (Amazon Echo) compatible light bulb and run a quick script?
10%..., 20%..., 40%..., 100%

Each bulb is addressable.

Well, that is a thought. I am using Google Home, but that is an insignificant detail. The advantage would be the color temperature could be controlled as well as the intensity. They are fairly expensive (~$60 for a 4 pack) every time one needs to be changed, but hopefully that would not be very often. I would need to bypass the existing controller, which is an idea that doesn\'t thrill me much.

I will need to consider this. I also need to do a little testing with one of my smart dimmers.

 

[whit3rd]

On Sunday, September 27, 2020 at 8:40:17 AM UTC-7, George Herold wrote:

That is fun!
Do NTCs, PTCs have lifetime, number of uses limits?
(I know I could search on DK... but that\'s work. :^)

PTCs definitely do; the motor start circuit in my fridge konked out a few years back,
and (1) GE parts department didn\'t have any stock, (2) it was available on eBay
only after I identified the 120V version (Chinese electricity is 220V, and there\'s
a LOT of 220V motor-start PTC aka \"relay\" available). Before the part came in
the mail, I\'d been tripping over ice chests in the kitchen for almost a week.

PTCs, though, ARE cheap; I got half a dozen spares.

If\'n you want a light to come up slow, resistive can work for you, but not if you want it to dim
gently as well.

 

[Jan Panteltje]

On a sunny day (Sun, 27 Sep 2020 17:22:01 -0700 (PDT)) it happened
\"rhor...@gmail.com\" <rhorerles@gmail.com> wrote in
<34fbc506-214b-43a3-a408-112747d93417n@googlegroups.com>:

On Sunday, September 27, 2020 at 1:40:53 AM UTC-5, Jan Panteltje wrote:
On a sunny day (Sat, 26 Sep 2020 14:42:14 -0700) it happened
jla...@highlandsniptechnology.com wrote in
badvmftp4m6r9vfsb...@4ax.com>:
The data sheet prohibits me from copying or printing it. OK, deal.
Here is my take, untested:
http://panteltje.com/pub/triac_trigger_r_IXIMG_0540.JPG

I am sorry, but I am having a very hard time making out your diagram. It is very dim, and no offense intended, but the writing
is not very legible.

Yes, my apologies, should have taken into account many of you earthlings still have simpler display system.
Do have a much higher resolution original, but just to simplify things
it is just an unijunction transistor generating trigger pulses for a triac.
If you type
unijunction transistor triac trigger circuit
in google and then select \'images\' you see plenty of examples.
The charge current in the timing capacitor sets the firing angle.
These days (but I still have some UJTs here) I would likely use a small PIC micro-controller
and use it comparators to detect zero crossing of the mains, and do the fade-in in software,
generate the trigger pulse in software, maybe add a transistor to drive the pulse transformer.

As to the LED light circuit diagrams, here is the circuit of the ones I bought on ebay from China:
http://panteltje.com/pub/LED_light_circuit_diagram_IMG_6925.JPG
the green is more in the center of you human beings light sensors.