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Author Topic: Smart Glass and Arduino  (Read 2263 times)
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Hi there,
I am building a kinetic sculpture, where the 4 different sides of a column are covered with smart glass film, top and bottom part won't be used.
The smart glass is a special material which has two states (opaque when not active and transparent when current is applied); it should be controlled by an Arduino and with a series of relay; each one of the films comes with two pads, one for the positive and the other for the negative pole, each one measures 9x50cm.
As all parts came without a specification regarding a circuit that could be built to control them I thought about posting it on the forum.
Power to each of the panels will be supplied via a transformer with the following specifications, I assume the panles will have to be connected in parallel:
The transformer is 200VA Isolating Transformer, (230>110v) Thermal Fuse self resettable (see attached img, with an output cable to be connected to the panels and an input to be connected to mains).

Questions I need to answer:
- Am I correct in thinking that I should connect all 4 panels in parallel?
- In order for me to be able to switch each individual panel at time, I need to connect the relays to the Arduino.
Should I buy a shield that comes with 4 relays already? I was thinking about using this one for instance, but it says that it cannot switch more than 35v DC per channel, am I missing something?
http://proto-pic.co.uk/4-channel-relay-shield-for-arduino/
- I have realised other projects with Arduino and motors etc but as this would be my first time playing around with big voltage, as I was wondering if wouldn't be a good idea that of buying a powerswitch tail (http://www.powerswitchtail.com/Pages/PSTIIU.aspx) but then I would I be able to control each one of the 4 panels?

One last thing, I am based in the UK.

Thank you very much in advance for all your help

Best

Faeve





* SF_01.jpg (159.25 KB, 567x378 - viewed 41 times.)

* SF_02.jpg (162.1 KB, 378x567 - viewed 58 times.)
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Dubuque, Iowa, USA
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Can you provide a link to tech specs for this film (manufacturer website / where you bought it, etc.)? You've hinted that it is switched with 100V AC but the minds on the board will want the full specs in lieu of making a recommendation that will burn down your house.

The relay board you have linked to is capable of 3A at 120V AC or 3A at 24V DC (according to the printing on the relays in the picture). Relays and switches are always rated separately for AC and DC current due to arcing on the switch contacts and how it differs with AC and DC.
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Thanks, I've forgot to add the specific of the smart glass.
This material uses:
Power - 110v
Frequency - 50-60 Hz
Electrical current - 0.1 amperes per square metre
Power consumption - 7 watts per square metre

each piece is made out of 9x50cm, so well below the square metre.

And here is the link to the manufacturer and specifically to the product:
http://www.prodisplay.com/switchable-smart-film.html

And here is the uploaded pdf with all the technical specs of the product:
https://plus.google.com/u/0/113031776563317981191/posts?hl=en
(double clic on the image so see the larger version)

Thanks for your help!
« Last Edit: August 27, 2012, 06:21:47 pm by faeve » Logged

Dubuque, Iowa, USA
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Make sure you have an appropriate fuse and switch somewhere upstream of the transformer <insert "you can die from high voltage" comments here>. I can barely see the colors in the picture, but the blue wire on the transformer input is neutral and the brown is hot. In the US for home wiring that would correspond to white and black, respectively.

One side of each panel would then be connected to the neutral (white?) from the transformer output. The hot/common (black?) from the transformer would be split into four wires, and each wire would connect to the four "COM"s on the relay board. You would then take four separate black wires and connect them between the "NO" (normally open) on each relay to the second pad on the panel.

It looks like a digitalWrite(HIGH) to any of pins 0, 1, 2, or 3 on the Arduino then activates the respective relay. Be warned that pins 0 and 1 will flicker when you're uploading a program to the Arduino so you probably want to disconnect the shield whenever you upload a sketch. There are cheaper relay boards out there (example and tutorial) that would be less restrictive in that respect -- while you can't stack them right on the Arduino you have more flexibility in which pins to use.
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Could you not use an LCD screen with out the Backlight?
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Hi Lakes and thanks for the advice. I am using the smart glass film as it is extremely thin and you don't see it when applied as it is transparent. It makes the sculpture looks kinda magical. I am afraid the LCD wouldn't achieve the same result but it is a very good idea for a future artwork. Thanks!
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No problem, would be interesting to see how you get on with the smart glass, as it seems to be a new product.
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Sure, I will post a log of all this adventure. So that it can hopefully be used by other ppl wanting to work with the smart glass. Once finished I will put a link on this thread in the forum!
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Thanks Chagrin
The cables coming from the transformer are:
Input (black cable) blue 0, brown 230v.
Output (white cable) blue 0, brown 110v.
I have contacted the manufacturer about the transformer, they confirmed that it outputs 110va current steeping down from the original 230va.
There is a fuse in the mains here in the uk, it is an equivalent of 13A.
They suggest that I run the power from the mains to the transformer and that then I connect this to an electrical junction box. This box would be connecting the transformer to each positive and negative poles of the panel.
Translating this into my project I would assume I would be following your advice by splitting the hot wire in the output cable (brown 110va) into 4 cables and have them inserted in the com of each relay.
Then the 4 negative wires as you suggested from the NO of each relay to the negative pad of each panel.
Where is the negative wire coming out of the white output cable (blue wire) supposed to go to?
I will sketch out a circuit diagram later on in the day, it would be very useful if you could review it for me.
Thanks for the suggestion related to the relay board.
Can I buy it and use it in the UK? I have seen that it is for the US market I wonder if it had the same specs.
I have found this Relay Board they sell in London, reading the specs sheet looks like it could be suitable for this type of project:
http://www.coolcomponents.co.uk/catalog/relay-module-p-926.html
Many thanks again for your help, I will use all necessary caution to avoid making a mess.

Best

Faeve
« Last Edit: August 28, 2012, 12:00:26 pm by faeve » Logged

Dubuque, Iowa, USA
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Don't refer to AC wires as negative or positive; they're hot and neutral. Confusing me smiley-wink

The neutral/blue out of the white transformer cable is split into four and one goes into each panel -- the remaining pad.

All of the relay boards discussed thus far should be fine for your use. The one you have linked from Cool Components is a bit mysterious on the 10-pin block; I'm not familiar with .NET Gadgeteer cables. It's fundamentally identical to the one I linked to at Arduino Direct but I'd have to see a closeup to tell which pin is which.
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Great! Thanks!
Just learning about Electricity and Physical Computing smiley-lol
Yes, I called the shop and they suggested I don't use the Gadgeteer.

So, at the end I happened to purchase a solid state relay (I am attaching the picture) and a mechanical one (from YourDuino http://arduino-direct.com/sunshop/index.php?l=product_detail&p=155) which I will use in conjunction with a Sensor Shield. The 4 channel mechanical Relay Board will arrive in 2 days I hope.
But for now I was thinking about using the Solid State Relay.
I have noticed that instead of having (NO, COM, NC), for each one of the Solid State Relays there are only two inputs (called A1, B1; A2, B2; A3, B3; A4, B4) and then one unique block on top where it reads: IN1, IN2, IN3, IN4, GND, GND, VCC.  
I will have a look online about how to connect the board to the Solid State relays and will send an update very soon!


* RelayBoard_01.jpg (171.16 KB, 567x378 - viewed 21 times.)

* RelayBoard_02.jpg (313.59 KB, 850x567 - viewed 21 times.)
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There is a problem with solid state relays when it comes to switching very light loads, which is what you have. You might have to put an other load in parallel to make it turn off correctly. Something like a 20W light bulb or a small heating element.
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There is a problem with solid state relays when it comes to switching very light loads, which is what you have. You might have to put an other load in parallel to make it turn off correctly. Something like a 20W light bulb or a small heating element.

Just to back that up, a web search suggests the SSR is an OMRON G3MB-202P which requires a .1A load.
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Thanks Grumpy Mike,
I didn't know that, uhmmm..... that makes it slightly more complicated as I will be hosting the SSR in small plinth. I have also purchased this mechanic model: http://arduino-direct.com/sunshop/index.php?l=product_detail&p=155
It will arrive in 2 dd from Hong Kong, I might have to wait and use that instead then.
Quick question, will I be able to use more than one relay at time?

Many thanks

F
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Quote
will I be able to use more than one relay at time?
Yes.
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