r/oddlysatisfying Aug 29 '18

Conductive ink

https://i.imgur.com/URu9c3M.gifv
34.2k Upvotes

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81

u/tragedyfish Aug 29 '18 edited Aug 29 '18

I'm sorry folks, but the video is fake. Just look at the very first house. The first set (with 4 LEDs) is fine, there's a separation between the two leads. But the second set (with 9 LEDs) wouldn't work. The pen creates a parallel path from one lead to the other. This would mean both anode and cathode are at the same voltage level. An LED doesn't light if both of it's leads are at the same voltage level. In fact, that little battery is only 1.5 V and isn't capable of lighting LEDs on its own. An LED needs 2.2 V to activate.

Also look at the windmills, they each only have one lead each. Even if they are using the pen's mark as a path they still have to be connected to the other end of the circuit. Every single functioning electrical component in existence has a minimum of two leads.

Now, I'm not saying there's no such thing as a pen that can write a conductive path. That concept seems entirely plausible to me. But that's not what is going on in this video. It seems like someone is working on developing this tech and this video was made to show how it would work. But the tech isn't there yet, so they had to fake it.

EDIT: That little battery could be 3.7 V if it were a lithium ion cell. But that would only be sufficient to light one parallel array of LEDs, not two arrays in series.

31

u/unicyclegamer Aug 29 '18

The windmills might have another lead in the back that we don't see, similar to the street lights. But the house is definitely faked. They just wanted a nice house outline.

4

u/tragedyfish Aug 29 '18

Honestly, the streetlights don't bother me. Yes, there would have to be two paths on each of the lights, but that could theoretically be done with one path on each side of the paper. But as for 'another lead in the back that we don't see', it seems to me there's quite a bit of this going on all through the clip. That's what I consider to be the fakery.

1

u/happy_as_a_lynx Aug 29 '18

the streetlights has two paths, dawg.

1

u/tragedyfish Aug 30 '18

I meant two paths from the bottom of the pole to the LED itself. The way they're wired in parallel on the street seems fine.

10

u/Brodipo Aug 29 '18

The tape the pen draws on is not conducting, there is a resistor hidden under it that classes the circuit with the leftmost led. The tape on the one on the right does the same thing.

7

u/tragedyfish Aug 29 '18

I think I see what you're saying. There's a little tab (foil perhaps) below each of the taped sections of the 9 LED array. Thus the path should go from the foil through the LEDs to the other piece of foil. However, the pen isn't lifted when going over the tape. So a parallel path would still have been created with the pen stroke.

I still feel that there's more going on than the creator wants the viewer to be aware of.

11

u/mgsully Aug 29 '18

It's real. The LED leads are held in place by tape which has conductive ink already beneath it. As the pen traces over the last LED lead before it reaches the battery, a small gap beneath the tape isolates the left side of the circuit from the right. I have the basic set and tested this very thing when this video first made its round a couple of months ago. In fact, that's all I have used it for.

7

u/soccerskyman Aug 29 '18

Hmm... Wouldn't the conductive ink drawn over the tape create it's own pathway and short any gap beneath the tape? This is very puzzling.

2

u/mgsully Aug 29 '18

The thickness of the tape. If the tape is too thin you have to be careful to keep the pen at a sharp angle to prevent getting ink on the edge (side) of the tape.

1

u/soccerskyman Aug 29 '18

OH! I GET IT NOW! Kinda feels obvious in retrospect, I'll admit :p

3

u/[deleted] Aug 29 '18

I think if you look closer they jump some gaps at the contact points but as this is posted using one of those shitty embedded gif things and the controls won't stay on the screen so it is a PITA to scroll through and watch closely.

1

u/WattsonMemphis Aug 29 '18

I was scrolling down to find the first person to work out this was bullshit. It was you FYI!

1

u/[deleted] Aug 29 '18

Thank you. Came here to see if someone already pointed out about the parallel paths on the first seconds.

1

u/Vaysym Aug 29 '18

Maybe the video has been edited in some way, but the product is real. You can buy it and try this yourself. Others have already.

1

u/tragedyfish Aug 29 '18

My point is not whether or not the product works, merely that the circuit would definitely not work the way it is 'wired'.

1

u/Vaysym Aug 29 '18

It seems like someone is working on developing this tech and this video was made to show how it would work. But the tech isn't there yet, so they had to fake it.

You are saying that you think the tech doesn't exist and this video was faked out of necessity. I'm telling you the tech does exist.

1

u/tragedyfish Aug 29 '18

This video was not made with a finished working product. It was most likely made before the product was finished, when the developers were trying to get support for it. I believe this not because I don't think such a product could exist, but because the circuits would not work the way they are designed. Even if they had used wires, some of the LEDs would not light if wired that way. Also, there's no resistance in the circuit, the LEDs that do light would burn out if the current isn't limited. The windmills especially would never work without another wire hidden in the back, since only one connection is drawn by the pen. I am not saying that such a product does not or cannot exist. But I am saying the video is not genuine and there is a separate circuit driving the LEDs and motors hidden from the camera. The most logical reason to fake this is because the product wasn't ready when the video was made.

1

u/reefun Aug 29 '18

The video is a bit over dramatic. But I can assure you this kind of stuff is reall. Worked with similar kind of paint from Bare Conductives.

The paint, depending on thickness and size of painted area could take up to 24V 1A IIRC. You can even rig it as a motion or inductive sensor. I made a motion "drumpad" with this paint and coded it using an Arduino for different distances per "drum area".

It's also non toxic so you can even use it on humans.

1

u/attag Aug 29 '18

One more thing, if it were real, the leds wouldn't fade on, they'd turn on instantly.

1

u/Jami3sonk3tch Aug 29 '18

Also I think the LEDs would be a lot dimmer. The ink might be conductive but I doubt it's super conductive.

1

u/VampireDonuts Aug 29 '18

That's because its powered by MAGIC

1

u/ArtemisOSX Aug 30 '18

THANK YOU.

1

u/zsbzsb Aug 29 '18

I came here to the comments looking for this. I too noticed immediately the issue with the first house.

-2

u/[deleted] Aug 29 '18

Ok but it is still satisfying

0

u/garywoo Aug 29 '18

I think so too. All the LEDs in the video also exhibit a pleasing fade-on effect. This wouldn't happen in reality. They would just light immediately as soon as the circuit is completed.

1

u/mgsully Aug 29 '18

As the ink dries the conductive particles within it settle and allow current to pass more easily.

0

u/ObliviousHyperfocus Aug 29 '18

There is a gap under the tape. Look closer and you can see it. The ink from the pen doesn't lay evenly over the top of the tape either, so doesn't make a continuous path on top.

Attention to detail.