[Solved]Smart Artificial Light as a Window

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
Hi there,
Please kindly read the problem here, I have not enough knowledge of electronics, your help is appreciated deeply :)

The Project
there is a room in the corner of an apartment, floor -1, there is no window possible there, I want to make an artificial light window in the absence of real one. that artificial light must turns on when sunrises in the morning and its intensity must increase up to the mid day then it starts to decrease until sunset it has to be shut down or almost off.

My Knowledge
I know a little bit in the term of electronics, for example I know that there should be a MOSFET in this project which its Gate has to be controlled by a light sensor, the MOSFET has to be suitable for 180 Volts DC (my SMD Diode strip specification).

The Problems
1- I absolutely do not know anything about how to choose that MOSFET!!!!! it seems there are a lot of different sort of MOSFETs.
2- How does the sensor actually should be set up to the MOSFET???
3- Anything I've missed???

Dear All readers, thanks for your patience, it is glade you've spent your time to read this, if you help me, then it will be much more awesome. :D
 

Sensacell

Joined Jun 19, 2012
2,622
While you have the basic idea right, the subtleties are far more complex than you might imagine.

The trick is being able to adjust the dimming to match your expectations.
You need to be able to adjust the sensitivity, span and offset of the system so it gives you that pleasing light at the right time of day, the gradual change that matches what a window provides.

This would be best done with a micro-controller and a bit of code, using PWM dimming.
The micro gives you the ability to format the sensor input to give you a dimming curve that looks the way you want.
It's actually rather hard to do this with simple analog circuits, it would become a painful exercise if you tried to do this analog.

In fact, I would not bother sensing the light at all, I would use the time of day to adjust the light output - much simpler.
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
While you have the basic idea right, the subtleties are far more complex than you might imagine.

The trick is being able to adjust the dimming to match your expectations.
You need to be able to adjust the sensitivity, span and offset of the system so it gives you that pleasing light at the right time of day, the gradual change that matches what a window provides.

This would be best done with a micro-controller and a bit of code, using PWM dimming.
The micro gives you the ability to format the sensor input to give you a dimming curve that looks the way you want.
It's actually rather hard to do this with simple analog circuits, it would become a painful exercise if you tried to do this analog.

In fact, I would not bother sensing the light at all, I would use the time of day to adjust the light output - much simpler.
actually first I thought about doing exactly what you said with Arduino and I know enough to do such that but the MOSFET is simpler and cheaper both, nevertheless if there is no way to make such analog system then I have to do it with Arduino but first I want to solve the case before stepping up!
 

Dodgydave

Joined Jun 22, 2012
9,651
I would use photo-transistors pointing to the sky verticle, or a solar panel pointing south at say 60 -75deg azimuth, and use the voltage to feed a 555 pwm controller to vary the white leds brightness. This will work automatically as the sun rises and sets and will turn off the leds at sunset, you can add a Comparator to ensure they go off at your sunset.
 
Last edited:

-live wire-

Joined Dec 22, 2017
912
Get a pack of photoresistors like this, and spread them out over a pannel. Combine them in series. This way, you get the average light, and it is not just that of one spot. Put them in series with a resistor of known value and measure the voltage across that resistor. The greater the voltage, the more light there is on it. Feed this to a 100-200Hz variable duty cycle VCO IC. This should feed into a mosfet driver IC, which should control the mosfet. If the mosfet is switching something that is not isolated from mains, you need an optocoupler to isolate the control circuitry from mains. Just look for a mosfet that can definitely handle the drain-source current and the drain-source voltage.
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
Get a pack of photoresistors like this, and spread them out over a pannel. Combine them in series. This way, you get the average light, and it is not just that of one spot. Put them in series with a resistor of known value and measure the voltage across that resistor. The greater the voltage, the more light there is on it. Feed this to a 100-200Hz variable duty cycle VCO IC. This should feed into a mosfet driver IC, which should control the mosfet. If the mosfet is switching something that is not isolated from mains, you need an optocoupler to isolate the control circuitry from mains. Just look for a mosfet that can definitely handle the drain-source current and the drain-source voltage.
Dear friend is there any way to draw it on the paper for me please, thanks anyway.
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
I would use photo-transistors pointing to the sky verticle, or a solar panel pointing south at say 60 -75deg azimuth, and use the voltage to feed a 555 pwm controller to vary the white leds brightness. This will work automatically as the sun rises and sets and will turn off the leds at sunset, you can add a Comparator to ensure they go off at your sunset.
dear, the LEDs are not the main source of light here, the SMD Diode Strip has 180 Volts and I guess transistors wont support it if I am not mistaken. so I want to use MOSFETs, any idea then?
 

Dodgydave

Joined Jun 22, 2012
9,651
dear, the LEDs are not the main source of light here, the SMD Diode Strip has 180 Volts and I guess transistors wont support it if I am not mistaken. so I want to use MOSFETs, any idea then?
So start by telling us how many leds you're planning to use, and the voltage requirements, then you'll get better results posted.
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
So start by telling us how many leds you're planning to use, and the voltage requirements, then you'll get better results posted.
actually I mentioned the SMD Diode strip I am going to use under the project part of my post
the voltage is 180 V
and current depends on the length of strip and the number of SMD Diodes, lets assume 100 of them.
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
Do yourself a favor:

Just buy really cheap 12 V LED strip from China.
Why struggle with complicated and dangerous high voltages?
actually the LED strip I have is Chinese but it is not 12 Volts!!! and also does not have any smart dimming capability
is there any led strip out there with smart controlling ability???
 

-live wire-

Joined Dec 22, 2017
912
If you can't make a PWM controller based on the light on some photoresistors or photoiodes, and don't know how to select a mosfet, then you shouldn't be around 180V! It is unnecessarily dangerous - you could easily kill yourself. Get a strip like this off of amazon. You can also get the same thing in warm white, if you want it to look less artificial and more like incandescent bulbs. Get a power supply that is the same voltage and is rated for more current than the strip should consume. Use a mosfet like the RCX200N20.

For the control circuitry, try something like this.
upload_2018-8-20_14-11-13.png
The resistors with the arrows are the photoresistors, and would be arranged in series on a panel. TL494 is a VCO IC. This is pretty similar to what this guy did in one of his videos. Skip to 5:25 where he talks about the IC.
 

oz93666

Joined Sep 7, 2010
737
actually the LED strip I have is Chinese but it is not 12 Volts!!! and also does not have any smart dimming capability
is there any led strip out there with smart controlling ability???
All led strips are easily dimmable . Don't drive over 12V or the life expectancy will suffer , at 11V they draw about a quarter of full power ,at 10V they draw about a tenth ... they cease emitting around 8V ..( figures approximate , varies with make)

Very important you use WARM WHITE .... easy on the eyes and closest to sunlight .
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
If you can't make a PWM controller based on the light on some photoresistors or photoiodes, and don't know how to select a mosfet, then you shouldn't be around 180V! It is unnecessarily dangerous - you could easily kill yourself. Get a strip like this off of amazon. You can also get the same thing in warm white, if you want it to look less artificial and more like incandescent bulbs. Get a power supply that is the same voltage and is rated for more current than the strip should consume. Use a mosfet like the RCX200N20.

For the control circuitry, try something like this.
View attachment 158427
The resistors with the arrows are the photoresistors, and would be arranged in series on a panel. TL494 is a VCO IC. This is pretty similar to what this guy did in one of his videos. Skip to 5:25 where he talks about the IC.
So many thanks for your help, hope to make it. :)
 

Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
If you can't make a PWM controller based on the light on some photoresistors or photoiodes, and don't know how to select a mosfet, then you shouldn't be around 180V! It is unnecessarily dangerous - you could easily kill yourself. Get a strip like this off of amazon. You can also get the same thing in warm white, if you want it to look less artificial and more like incandescent bulbs. Get a power supply that is the same voltage and is rated for more current than the strip should consume. Use a mosfet like the RCX200N20.

For the control circuitry, try something like this.
View attachment 158427
The resistors with the arrows are the photoresistors, and would be arranged in series on a panel. TL494 is a VCO IC. This is pretty similar to what this guy did in one of his videos. Skip to 5:25 where he talks about the IC.
dear friend I cannot recognize the red sign I put, in the circle I mean, does it connect? or what? please kindly make me correct thanks
 

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Thread Starter

farzad latifeh

Joined Oct 3, 2017
59
OK guys after months trial and fail based on what -live wire- and others said and explained me, I made it and it is actually working almost well. also I took 12 V advice and didn't try high voltages, thanks for your advice :)
I just want to put the schematic here for anybody who likes to know what will be the result of this post finally. However, the LED strip blinks in very low lights in the morning and as far as I searched, it is a big deal even for big companies like DELL, since LEDs (Screen or what so ever) even in frequencies like 15 kHz blink in low duty cycles and it is the main reason of headache and nausea for some phone and tablet and notebooks when the screen brightness decrease below some values. on the other hand this system is working very smooth and well stable with 12 V car incandescent lamps.
123456789.jpg

Edited: BTW in any case if anybody wants to make the system in reverse mode like to be on in darkness and off in light, they just need to change R1 with LDR4, then the system works with amount of darkness instead of sun and light, actually as much as darkness increases the system brightness will increase.

Edited 2: and if you put a Potentiometer instead of R1, then you can control the sensitivity, the problem here is the Maximum Voltage for FB in TL494 datasheet is rated 4.5 V while I tested even 12 V with no error, but I prefer to set it under it's critical value since I don't want it to be blown after a while. :)
 
Last edited:

BR-549

Joined Sep 22, 2013
4,938
Are there any lifeforms in the room? To prevent behavioral and growth problems.....use an outside sensor for dimming control.
 
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