Instructables

Making a Touch Sensitive On/Off Circuit with Bare Paint and a 555 Timer IC

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Picture of Making a Touch Sensitive On/Off Circuit with Bare Paint and a 555 Timer IC
In this tutorial we are going to make a simple touch sensitive circuit using some Bare Paint, a 555 timer circuit, a couple of resistors, a LED and a capacitor. The 555 timer is a fun and versatile integrated circuit (IC) that can be used in several distinct ways. There are loads of interactive circuits that can be made with this chip, we'll be adding tutorials illustrating more of these projects in the future. Today we are  using the 555 with its internal flip-flop to sense the change in voltage at two input in the circuit.

When you touch the Bare Paint on either side of the gap you connect the circuit through your skin – don't worry, the current is so low you will not be able notice it. The 555 timer senses voltage change at pin 6 and pin 2, depending on which button you press and flips the output state at pin 3 - turning the LED ON or OFF. By the end of this tutorial you will have painted two touch buttons, with Bare Paint or a Bare Pen, that connect to a touch sensitive ON/OFF 555 timer circuit. Once you have got this simple circuit going you are free to get even more creative in using the paint to make different graphical touch buttons. Please send your electro-art works to us to put up on the community site!
 
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Step 1: Components

Picture of Components
For links to purchase these components visit our tutorials page at: http://www.bareconductive.com/555-touch-circuit

Bare Paint
Paintbrush
Paper
LM555 Integrated Circuit
Resistors
Bread Board
Jumper Wires
Capacitor
LED
Paper Clip Wires
9V Battery
Battery Clip


BeyondTheSky11 months ago
I think this idea is amazing! Thank you for sharing this project.
I just wanted to know, is there a substitute for Bare paint? Thanks.
tplim1 year ago
Thanks for sharing
PeterBr2 years ago
Hi,

One suggestion:

A circuit diagram as well as the "breadboard schematic" would be most helpful for those of us who'd like to hard wire the circuit without doing a breadboard layout first. Sorry if it's in the 'ible somewhere but I couldn't find it.

Thanks for sharing this - I have many ideas for it already :-)
BareConductive (author)  PeterBr1 year ago
Hi PeterBr,

The circuit diagram should be on the same page as the breadboard schematic on Step 6. Let me know if you have trouble finding it.

Glad you enjoyed the tutorial!
can you solder to this stuff? It would be cool to try to laser cut a pcb stencil, drill it, and then solder components to it.
BareConductive (author)  amandaghassaei2 years ago
Hi Amandaghassaei,

You can't solder to it, but you can use the paint itself as a cold solder or glue to attach the components so there's no need to!
alright, here it is:
http://www.instructables.com/id/Flexible-Circuits/
ok, then maybe you could glue a backer over it or put some tape on top to keep everything in place. We still have some of this in the office, I think I'll try it sometime!
charles5432 years ago
You don't need conductive paint. Just use wires.
sir, can I use carbon ink instead bare paint....................!
mutha292 years ago
Hey, just wanted to say--Nice article! I saw the 9 volt "flashlight" battery used. Is there a minimum or maximum for the power source to be used with a bare paint switch. Do you shock the person? Would it be necessary to make like a little solenoid with human/bare paint and then make that thing jump and trip a bigger switch for bigger power?
BareConductive (author)  mutha292 years ago
Hi Mutha29,

The 555 works with a voltage between 3 - 15 volts DC. It will work well with 6 volts (4 AA battery pack). It can still work with lower voltages, but you will sacrifice on LED brightness. I have successfully used a 3.7V lithium Ion battery with the circuit, but find 6 to 9 volts gets the LED to a nice glow. At less than 3 volts supply the 555 will no longer work properly.

There is no need to worry about getting a shock with this circuit - the current going through the touch points is incredibly low (due to the 3M ohm resistor) that you won't even register it.

You can use the paint to trigger higher currents using an Arduino and a relay - see Matt's tutorial, link below - which switches a mains light on and off. Always be careful when working with high voltages and currents.

http://www.bareconductive.com/bare-paint-lightswitch

Good luck!
Schematic needed here!
BareConductive (author)  emerson.john2 years ago
Hi Emerson John,

We have just added a circuit diagram to the steps.

Thanks for the suggestion!

vricsi942 years ago
(removed by author or community request)
BareConductive (author)  vricsi942 years ago
Hi Vricsi94,

We actually only sell the paint online. You can get it on our website and we have free shipping http://www.bareconductive.com/store so it will make it to Hungary in 7 days or so.

Otherwise you could try making a paste with graphite but I'm not sure how well that will bind.

Good luck!
Conductive paint is sold by other companies, and one can even make conductive paint/ink fairly easily.
How do you make conductibe paint easily please?
Try this Instructable:
http://www.instructables.com/id/Conductive-Glue-And-Conductive-Thread-Make-an-LED/step1/Make-Conductive-Glue-Conductive-Paint-and-Conduc/
I tried the low resistance glue version, and was able to use it to get a good connection to the back of a solar cell, but for this application the higher resistance ink formulas should be fine.
Thanks guys, much appreciated.
Jack
Thanks!
Now I have an idea: would it work if I replaced the power button of my computer with something like this?
Make sure the voltage/amperage is low, and use something non-conductive but also not moisture absorbent (like paper is) as a backing (maybe a plastic of someo sort). You don't need it starting/stopping your computer when it gets humid out :-)
rey_salasjr2 years ago
nice....
tjfoth2 years ago
In some research we did a number of years ago, we found that there is sufficient carbon in either laser toner or black inkjet ink to accomplish pretty much the same thing...
Goodhart tjfoth2 years ago
Graphite from a hard pencil is usable in some circumstances too