
Circuit Scribe: Draw Circuits Instantly - hkbarton
http://www.kickstarter.com/projects/electroninks/circuit-scribe-draw-circuits-instantly
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revelation
_... a conductivity of 50-100 milliohms per square per mil ..._

That's pretty bad. Cue the video of him measuring 50 Ohms for that small
scribbled line...

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DonGateley
Yeah, it will be fine for high impedance signal paths, which are by far the
majority of traces, but not so much for power. I'm not sure what to use for
the power traces and hope they come up with some solutions or suggestions. As
an EE I know where it is appropriate and where it's not and would hope that
design/layout software could make that mechanical just because it's easy to
do.

I jumped on the project as soon as I saw it and will be thinking about a
solution myself.

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solistice
drawing over a given trace several times depositing more material might do the
trick.

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DonGateley
That could be hard to do freehand. There is a KS plotter project, the
WaterColorBot, which is very inexpensive and should be easy to adapt to this.
Then, over-tracing and creating multiple overlapping parallel traces could be
rather easily achieved.

With regard to this question they responded,

"2\. There are ways to reduce the ohm rating when dry, simply rubbing the
trace with a hard, smooth surface like a rounded pen cap will decrease the
resistance by increasing particle to particle contacts 3\. The ink can support
a maximum current of about 175 mA on standard copy paper. Higher currents
cause joule heating and a subsequent drop in resistance due to sintering the
particles (up to around 8x decrease in resistance if controlled). Currents
exceeding 400 mA may break the trace on standard copy paper. High currents can
be achieved with photo paper, near 800mA. 4\. Currently, the ink will only be
available via rollerball pen, but this can be adapted to be used in various
plotters. We will have videos and demos of this shortly. 5\. Conductive
adhesives will work with the ink"

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albertyw
From the article they published in Advanced Materials, it seems the ink
actually contains silver (the element) nanoparticles in a colloid. I'm
surprised that the resistance is still that high.

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sitkack
Oh good, more nanoparticles around the kids.

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yitchelle
I can see this as part of one of those electronic kits ([http://www.kosmos-
shop.de/Elektronik/easy-elektro-start/kosm...](http://www.kosmos-
shop.de/Elektronik/easy-elektro-start/kosmos_1446/)) that I got as a kid.
Instead of having physical metal rods to connect all the circuit elements,
they would supply a couple of these pens and a stack of papers.

It might reduce the obstacles for getting more kids into science and
engineering.

For the real stuff, I am not so sure...

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DonGateley
Yeah, I've been wanting to make a high order yagi antenna for FM for a long
time but have been daunted by the construction. All I need with this is a
piece of cardboard, a ruler and a nub to compress the traces when dry for
better conduction. :-)

They did some experiments with HF antennas like for WiFi or cellular and it
didn't work so well but I think there is a HF limit with it that FM should
fall far below.

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jlas
Neat, but seems like a novelty.

As far as usage in teaching circuits, it wouldn't be very useful after the
first class. The bulk of learning about circuits is math.

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jmpe
That's because it is a novelty. You're pretty much restricted to planar
circuits with this approach and the resistance is pretty bad.

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DonGateley
Not at all. You can paint over a crossover with something (Whiteout I think)
and then just write across it. When you can do that it's far more flexible
than multi-layer with via's.

The resistance will not be an issue either for signal traces. Only those
receiving or delivering power such as Vcc or the output of an audio amp or
cable drivers.

I'm looking to enhance it with software for another KS project WaterColorBot,
a very low cost plotter. With that, multi-line overlapping traces can be
created to lower resistance and it could even automatically implement their
suggestion of rubbing over a dried trace with something hard to compress the
colloidal silver in it into making better contact between particles.

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therobot24
what happens when you put too much current through? Does the notebook go up in
flames? Having seen many fellow classmates flip polarities to watch caps
explode, i can see them lighting up their notebooks with this..

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solistice
Hooking up 230 V to a 2 cm @ 100ohm/cm resistance trace would generate about
250W of heat (unless I'm miscalculating something), which is about the power
rating of a beefy soldering iron, or an amnemic hair drier, and at that
lenght, it should be enough to ignite the paper. However you have to consider
that

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jaytaylor
How is this different from a Circuit Trace Pen [0]?

[0]
[http://www.amazon.com/gp/aw/d/B0002BBVQO](http://www.amazon.com/gp/aw/d/B0002BBVQO)

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platinum1
It dries faster. I believe that's competitor #2 in the video.

