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

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## Introduction: 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!

## Step 1: Components

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

## Step 2: Materials

The first step is to gather the appropriate materials mentioned above. To make this nifty circuit you will need:

1. A jar of Bare Paint, paint brush and paper, or use a Bare Pen

2. A 330 Ohm resistor, two +-2.7 Mega Ohm resistors (make sure it is sufficiently large for greater sensitivity), one 10nF capacitor (0.01uF = 10nF = 10 000pF) and a LED

3. Some wire to make your paperclip wire connectors (see Connecting to Bare Paint for how to)

4. Solder-less  breadboard and some jump wires

5. Some paper or other non-conductive material to apply the Bare Paint

6. A 9V Battery and a battery clip with wires.

## Step 3: Painting the On/Off Touch Buttons

Before you start to paint your buttons onto a non-conductive surface, such as paper, think about what form you would like the graphic to take. You can think of the 'button' as a line of paint with a gap and at that gap you connect the circuit with your finger, thumb or other body part. So make sure it is narrow enough for this. A very small current, imperceptible to a human, flows through across your skin when you bridge the circuit over the paint-gap.

Second, paint your decided button graphic onto your surface with Bare Paint and a paintbrush. I have done this on paper and used a thin piece of masking tape to ensure a clean thin break at my touch points. Below is my finished pair of touch buttons after being left to dry for several minutes. I have made sure that the lines come close to the edge of the paper so that they can be reached by a paperclip.

## Step 4: Placing the Components and Connecting the Circuit

The next step is to assemble the simple circuit (pictured in the image below). Take a good look at the breadboard schematic and make sure you have connected the circuit up correctly. You can download a copy of the breadboard schematic above.

## Step 5: Adding the Paperclip Wires

Once you have your circuit setup on your breadboard you can place your paperclip wires in the tracks indicated in your schematic and in the images below.  Take a look at our connecting tutorial which shows you how to make these cool prototyping wire - and other interesting ways to connect to Bare Paint.

## Step 6: Circuit Diagram and Breadboard Schematic

Make sure to double-check your connections using the circuit diagram and schematic below. You can use this while you follow along in the tutorial video, pausing the video when you need to get a closer look at which tracks are being connected.

## Step 7: Testing

You can test it by first touching the blue paperclips together to turn the LED ON and then touching the yellow pair together to turn it OFF.

## Step 8: Connecting to Bare Paint

Now you can connect them to your touch buttons using the paperclip ends of the wires. Connect the blue wires to your ON touch button and your yellow wires to your OFF touch button. Now you can simply place your finger, thumb or other body part at the gap to control you LED! It's that simple!

## Step 9: Completed Circuit!

If this is working for you, you can now start experimenting with creating more interesting painted buttons with your paint - they don't even need to look like buttons. Try using vinyl cutouts as stencils or even try screen printing if you have access to the equipment. Check out these cool painted button below! Make sure to send in your crazy work so we can post it on our community wall - email us at community@bareconductive.com.

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## Questions

Hi, the pdf schematic is different from your circuit and your last schematic.

Hi IkraamG,

Could you let me know exactly how it's different so I can confirm??

if you dont mine sir i need a VIDEO of this circuit

i did this experiment but were i did mistake i'm nt getting i tried dis circuit fo 3tyms led continuously glowing..n i have to submit this case study in another 1:30 min

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.

Hi there, you can use something else conductive. We like using our paint as you can create your own graphics on paper. Thanks!

Is there is any video how to connect components in breadboard??

I'm afraid not on our site!

Thanks for sharing

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 :-)

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.

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.

2 replies

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:
https://www.instructables.com/id/Flexible-Circuits/

You don't need conductive paint. Just use wires.

sir, can I use carbon ink instead bare paint....................!

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?

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!