Blink Program Using PDLC Film

Good afternoon people, firstly let me say thanks for everything in advance. I've learned a lot from this forum and this is my first post I think, I signed up ages ago and have only just got my arduino uno and started playing around with it.

Down to my question. I am working on a project and part of it involves a box with windows on every side. The windows will have panels on them and these panels will be sheets of PDLC smart film.

I wrote a program using a 6 channel relay that randomly switches the relays on or off. It works brilliantly with LEDS. So today I decided to use just one relay linked up to the PDLC film and wrote a basic blink program to switch it on, delay for 2 seconds then off, as a test.

The problem is, the film switches on fine (opaque to transparent), but when it switches off it fades back to opaque instead of instantly. It's almost like the voltage is going from high to low gradually instead off instantly. It's hard to explain so I uploaded a video on youtube of it.

The film came with a button witch the runs off two AA batteries, I don't know much about electronics but I'm guessing I'm missing something in this circuit which is responsible for the switch from opaque to transparent being instantaneous. The switch works like this: Push it once turns the film off (opaques to transparent), puch it again turns the film on (transparent to opaque).Here are some pictures of the circuit from the switch that came with it along with some pics of my breadboard circuit. The circuit is the same as this one (credit microcontrollerslab.com) except it's just one relay, the led and resistor are replaced by the PDLC film and the batteries are replaced by mains voltage (I'm in the U.K. so that's 240V I think).

Breadboard:
(EDIT: Just noticed that the hot wire from the relay is in the wrong position on the breadboard. I actually noticed this after I took the photo and corrected it before I took the video)



PDLC Switch Circuit:



So the main problem in a nutshell is that the film is not switching on or off instantly. Can anyone help me with my problem? What's causing this fading issue and how do I fix it, what am I missing in the circuit that should cause the film to switch off instantly instead of gradually fading off?

Thanks in advance.

Do you have any link to the specs on the PDLC panel?

Unfortunately I don't. I bought it off Amazon and it came with a few pages (in Chinese) of how to install it but not any technical specs. All I know for certain is that it only runs off a high voltage. I tried hooking up a 24V transformer and it didn't switch the film, so I wired it direct to a plug which I plugged direct to mains 240V and it switched fine. I'm guessing that big block thing in the switch circuit is some sort of step up transformer? As I said, I don't know much about electronics sadly...I'm trying my best to learn.

Ok, stop right there! What you are doing is extremely dangerous! You should never connect anything to the mains voltage without safety precautions and a full understanding of high voltage safety and operation!

Actually, just checked the booklet that came with it and there are some specs, but they're in chinese.

Thanks for the heads up, what would you suggest I do to connect it safely then?

What voltage and frequency comes from the module?

Have you Googled PDLC?

Yes I've researched eveything on PDLC for months but nothing describes my issue.

Months of research and you don't have any specs at all? ??????

I posted the specs above, they were in the booklet but they are in Chinese.

What is your hope? That you can manufacture a substitute module for the Chinese one? Seems unlikely for someone that self professes a poor knowledge of electronics. Just trying to get a sense of what you need. You already do know that it uses high voltage, so you obviously can't just connect it to Arduino pins.

No my hope is to simply switch it off and on randomly at random intervals. But the film switches on instantly but switches off gradually instead of instantly. There's something in the module that I am missing in my circuit that is preventing the film from switching off instantly like it switches on. I need to know what that something is so I can implement it in my circuit.

I'm not running it off arduino pins, it's being switched via a 5V relay.

Measure the voltage coming from the driver module. CAREFULLY! IT IS HIGH VOLTAGE AND COULD STOP YOUR HEART

While we were talking here, I googled PDLC and came up with several different manufacturers specifications. It seems different panels work with different drive voltages from 80-110V, but no mention was made of frequency. This is why you need to measure the voltage and frequency of the converter.

Do not now, or even again in future, play with wires that are attached to the mains power. Killing yourself is not fun, but killing someone else is really tragic.

If you want help with your circuit, please post a schematic (wiring diagram).

Thanks aarg, I've heeded and taken note of your advice and shall be more careful in the future. I have a multimeter but am not sure what setting to put it at. Sorry this is all new to me, I didn't realise something so simple would turn out to be a nightmare and it's such a crucial aspect of my project.

Set your meter to VAC, a scale over 200V. Post a wiring diagram. A real one, not a Fritzing diagram with a lot of "except that this is that" explanations... thanks for the images, they are somewhat helpful.

Why do you not just use the driver module, and switch the power to it? It looks like it takes 2 AA batteries?

It does seem unlikely that a person with little experience in electronics could build a custom driver board for a display with vague specifications. Not to pour cold water on the project, but it seems to me very unworkable. You need a different approach.

You have a working panel (I hope, after connecting it to 220V), and a working driver module. Best to try to use that. As a simple example, the relay could operate the switch on the module.

Well not to be confrontational as your advice is welcome but it really was a simple idea until I ran into this problem. As I said I already have a working circuit that randomly switches 5 LEDs on and off at random intervals. To me, my thoughts, were that it would be as simple as replacing the LEDs with the PDLC film...simple in theory but this fading issue was something that was unforseen.

Anyway, I measured the voltage...probably did it wrong, but I got a reading of 144.

Using the module doesn't help, I tried that first before using the mains and the fading issue is still present.

Now I'm confused. You say you used the module before, does it also fade with the module? So, under what conditions did you actually see it turn off quickly?

Also, the problem itself is the source of any difficulty, not anything I can say.

Yes the first thing I did was to wire the module into the circuit and test it with the relay. Two problems arise, the module has a switch that is on when you push it once and off when you push it again which means the button has to be held down to complete the circuit. And yes, the fading issue is still present.

The PDLC film works under the correct conditions if the module is connected straight to the film.