Instructables
Picture of Printing Circuits with Conductive Paint
After making a flexible circuit, I wanted to experiment with other ways of working with conductive paint.  I saw this project posted by the people who make Bare Conductive paint and I had the idea to try to create a circuit on paper using lithography.  This is just a sample project I tried, it's a finger activated 555 synthesizer.  You could use your own parts and circuits with this technique, though you need to be aware of how the increased resistance on the traces will affect the electronics.  I made this project a while back, and unfortunately seem to have misplaced my final images, so this documentation is a little more about the technique than the actual project.

Parts List:
Bare Conductive Paint Pen Bare Conductive
0.01uF ceramic capacitor Digikey 399-4324-ND
1kOhm 1/4watt resistor Digikey CF14JT1K00CT-ND
555 timer Digikey LM555CNFS-ND
9V battery clip Radioshack 270-324
copper conductive tape Amazon
amplifier and speaker
paperclips
22 gauge jumper wire
Paper
Paint brush
Blue painter's tape
 
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Step 1: The circuit

The circuit is pretty simple, it centers around a 555 timer IC.  The 555 timer is wired up in astable mode, meaning that it will be outputting a continuous square wave, with a frequency dependent on the resistance between the two pins labelled "POT" in the diagram above.  The only extra components needed are a 1kOhm resistor and a 0.01uF capacitor.  The circuit is powered by a single 9V battery, connected at the ground and 9V pins.  A speaker is connected to the ground and output pin (pin 3) of the 555.

I also included a jumper wire in my circuit, indicated by the two pins labelled "jumper" in the schematic above.  A jumper wire is a wire that connects one part of a circuit to another in case it is too difficult to find a path for it on the printed circuit board (PCB).  Pins 4, 5, and 8 should all be connected to 9V, but since they are on opposite sides of the 555 timer this was a little tricky.  As you can see in fig 2, I already had conductive traces running under the 555 timer, so I had to use a jumper cable to connect pins 4 and 5 to 9V without running into other traces or taking a very long path around the chip (although this might not be a problem with regular copper traces, a long path with conductive paint will add some unnecessary resistance to the circuit).
This is REALLY cool! But I am having a hard time understanding the point of this project. What does the final result do? Is this to go on an article of clothing? Or let me asked this another way... What is this technique used for specifically? In what circumstances would you want to use conductive paint? Please pardon my ignorance, I don't really understand electronic components, though they fascinate me.
Thanks!
Thanks!
there's been many times i've been short of cash, and out of copper clad. sticking the pins through cereal box cardboard and soldering point to point works for a LOT of things, this might work well to make boards on plastic ice cream tub lids.

if someone might dare, they could possibly draw the circuit on the bottom of a storage container, some glue to keep heavy items from flying off if it's dropped would probably help too.
amandaghassaei (author)  skaar1 year ago
maybe, but you have to remember there's a decent amount of internal resistance in this paint. It will affect your circuit.
mmhmm, but i've seen some low resistance silver ink and epoxy, i think on the weller site, a few years back that might do the same job.
amandaghassaei (author)  Gueritala101 year ago
the final project is a synthesizer, I just didn't document it very well. I figured I would just post what I had instead of deleting it...
jokickass1 year ago
instead of the jumper you could have just drawn a trace from pins 4, 5 and 8 on TOP of the chip.
amandaghassaei (author)  jokickass1 year ago
that's a good idea!
Or put the trace between pins 5 and 8 on the bottom of the paper. You would need to poke holes through and mount short pieces of wire to get the effect of a plated through hole on a two sided board.
amandaghassaei (author)  pmartel1 year ago
yeah I'd love to see someone try this
SJU871 year ago
I wonder if you put 3-5 pin holes in the paper if the paint would conduct through the paper to the trace on the other side and eliminate the need for wires through the paper? I see the pen is just $10 and available at my local Radio Shack. I love that they have the "Find it in your store" link now. When did they start that? Anyway, I digress. My next thought is to coat it with hot glue or spray varnish to hold items on. Great instructable!
amandaghassaei (author)  SJU871 year ago
great ideas!
wizer1 year ago
What is the difference between Bare Conductive paint and normal Silver conductive paint?
SJU87 wizer1 year ago
That would be a great school project. Kids could put down lines of each and measure the resistance across various distances, examine the product makeup and try to determine why there is a difference (if there is). It seems based on a quick look that silver is more expensive, although, if you're not careful, you can pay nearly as much for a BC pen!
pmartel1 year ago
Or on the bottom of the paper.
synthdust1 year ago
How well does this conductive paint hold the components to the surface?
amandaghassaei (author)  synthdust1 year ago
it's still very fragile, even when you have everything stuck with a big glop of paint, it's hard to get metal wires to stay on paper. The chip is fine, it's the resistor an cap that can potentially get knocked off.
qtz1 year ago
Amazing , very useful ,thank you
Now, make an LED blinky with surface mount parts.
zawy1 year ago
The conductive ink seems interesting, but the manufacturer completely misunderstands conductivity in their spec sheet and gives no specifications for the tensile strength (or conductivity or resistance). Their discussion makes no sense in either electrical engineering or basics physics.
amandaghassaei (author)  zawy1 year ago
http://www.bareconductive.com/file/2013-technicaldatasheet-bareconductivepaint-pdf
Yes, that's the discussion I'm referring to that makes no sense and provides no intelligible information. Your comment that you measured 600 ohms per inch tells me a lot more than their 2 pages on resistivity.
Hallofo1 year ago
Nicely done! Now I have yet another excuse to get a laser cutter...
Very Interesting.