Introduction: Feltronics

About: Cleverly disguised as a responsible adult

Feltronics turns your refrigerator into a soft circuit breadboard (a large format electronics project kit). That is, you can make real, working electronic circuits and projects using big fuzzy felt pieces, and stick them to metal surfaces. Hackerspace Charlotte took home the Grand Prize from the Global Hackerspace Challenge with this project in 2011. In this instructable we present an easy method for creating your own Feltronics set. This set have the four simple parts that can be combined to demonstrate a simple and beautiful circuit that lights up an LED at the touch of a button, that looks great on your refrigerator.

This video is from a Tech Talk given at Skookum. It uses Feltronics to demonstrate the electronics in a simple radio:

These two videos demonstrate basic electronics to kids at the Discovery Place, a children's science museum in Charlotte, NC. We armed the kids with lasers and asked them to point out the path of electricity.

Discovery Place 2

This video shows an early demonstration of Feltronics at the 2011 Atlanta Mini Maker Faire. You can see the [not quite finished] RGB LED mixer circuit at 2 minutes and 4 seconds in (sorry, deep linking doesn't seem to work).

Step 1: Laser Cut the Pieces

Download the zip file containing the template cut files (vector graphics), choose the format for your Epilog Zing 16 Laser Cutter and cut the following for a simple series circuit:

Black Felt:
                    4 x Outer Layers
                    1 x Battery Schematic Symbol
                    1 x Resistor Schematic Symbol
                    1 x Button Switch Schematic Symbol
                    1 x LED (Diode) Schematic Symbol

White Felt:
                    4 x Inner Layers.

We have cut out zillion felt parts, and can say without a doubt a laser is the way to go. You can cut the parts with scissors but it's the single most time consuming step. So if you would like to see more of these parts in the wild please feel free to login (or create an account on Instructables.com ) and vote for us in the Epilog Laser challenge (you'll have to login and actually enter into "voting mode" in order to vote).

Step 2: Alternative to Laser Cutting (Skip If You Haz an Epilog 16 Zing Laser Cutter)

Not everyone has a laser - We briefly were able to borrow a laser to cut some pieces and it made a huge difference in the quality and speed that we were able to create parts.  We would desperately love to have a laser, and we would immediately put it to great use.  So please vote for us in the Epilog Laser Challenge (you will need to create an account and/or login to vote).

If you don't have a laser, you will need to first print the templates and cut them out of paper and the use those paper templates to trace the pattern on to felt to cut, or just hold the templates over the while you cut.  Either way after you do that once you'll know just how much having a laser means to us.

Download the zip file, choose the format for your Epilog Zing 16 Laser Cutter and cut the following:

Black Felt:  
                    4 x Outer Layers
                    1 x Battery Schematic Symbol
                    1 x Resistor Schematic Symbol
                    1 x Button Switch Schematic Symbol
                    1 x LED (Diode) Schematic Symbol

White Felt:
                    4 x Inner Layers.

Step 3: Tools

1. An an Epilog Zing 16 Laser Cutter (not shown - because we don't have one, hint hint - vote for us!)
2. If you don't have an Epilog Zing 16 Laser cutter - a Pair of Scissors* (note: this is not as good as a laser)
3. Wire Strippers.
4. Heat Gun (also not shown, but we have one) - may use a Hair Dryer - (look under the bathroom sink)
5. Glue Gun

Step 4: Parts List

Black and White Felt (Laser  Cut  using these Templates - we recommend using an Epilog Zing 16 Laser)
24g Stranded wire
3/16" Heat shrink
10mm x 3mm Ring Magnets

LED (or substitute your desired component)
1 Coin Batteries & Holder
Momentary Button Switch
100 Ohm Resistor

The PDF template files are attached so you can cut the templates by hand with scissors or on your laser (highly recommended).  Most of the parts can be found on eBay such as the Extension Springs - Stainless. Other parts like the ring magnets can be found with reasonable prices on sites like K&J Magnetics  or Super Magnet Man and others.  Felt is readily available for your local fabric store, but don't get the little rectangles, by the yard is far more economical.

If you shop carefully the cost per part should be less than $1

Step 5: Strip Wire Leads

Cut a single piece of 24 gauge stranded wire approximately 8 inches in length.
Strip 3 inches of insulation off one end , exposing about an inch of bare wire. We recommend leaving the extra insulation on the wire as this will provide extra structural support.

Step 6: Attach the Magnet to the Wire

Thread one of the ring magnets onto the stripped portion of the wire
Wrap the wire around the magnet and thread it through a two more times
Finish with the wire running back parallel to itself and cut of the extra inch of wire sheathing

Step 7: Add Heat Shrink

Slide 2 inches of 3/16" heat shrink tubing over the long and short wire ends
Head the wire with a hot air gun or a soldering iron or even the tip of a hot glue gun
Be careful not to heat up the Magnet!!  The magnet will be degaussed if it gets too hot.

Step 8: Glue Schematic Symbol

Apply hot glue to the feltronics  schematic symbol
Avoid putting glue into the laser cut holes for the wires

Flip the symbol over and onto the white felt piece
Line up the wire holes in the top layer (octogon) 
Avoid smushing glue into the laser cut holes for the wires

Step 9: Attach Spring Terminal

Strip 3/4 inch of insulation off the other end of the Wire and insert the wire through the top felt piece.
Bend the spring in half so the end loops are next to each other
Thread the stripped wire through the spring loops
Bend the wire and twist it around itself to hold the springs

Step 10: Final Assembly

Apply additional hot glue to the back of the white inner layer,
Flip it over and center on the black outer layer,
Flip it once more and Iron from the Bottom - this will ensure the top of the piece is flat.
Insert your LED by squeezing the spring and jabbing the lead in (and out)

Step 11: Make a Circuit

You can make circuits big and small, simple or complex with Feltronics.  All you have to do is make more pieces in for your electronics project kit and you're on you way.  If there is a new schematic symbol that isn't in your kit just cut one out.  

A few of the circuits we've made so far:
    Simple series circuits (analog 'AND' logic)
    Simple parallel circuits (analog 'OR' logic)
    Complex series and parallel circuits (AND with OR in various configurations)
    AM Radio (with only 5 components!!)
    FM Radio (with a few more)
    Flip Flops (a-stable multivibrator)
    Analog Multi-meter (Analog to Digital to Servo Control) with an Arduino
    RGB LED mixer
    And many more

We have also evolved are manufacturing process over time.  Presented here is what we believe to be the best combination of the cheapest, easiest, most reliable  for home manufacture.  We have included several of the iterations  in these pictures to give you an idea of some of the other possibilities.
Magnets in the middle of parts for connectors with washers on component leads
Magnets in the middle of parts for connectors with magnets on component leads   
Magnets in the middle of parts for connectors with component leads sandwiched between magnets
Washers in the middle with magnets on component leads
Sockets in the middle with components plugged in
Alligator clips in the middle holding onto component leads
Foil tape (HVAC tape) wrapped [regular] magnets
Springs in the middle with component leads poking through (as used in this instructable)
Header type connector on the side of the Feltronics piece with components sticking in (for mass production if we ever get a laser - hint hint)
And surely a few others that I've forgotten.

Please share your designs and ideas for others.  We'll post more schematics and templates just as soon as we clean them up.

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    9 years ago on Introduction

    "a simple radio", 'eh? Have you worked up a feltronics microphone yet?


    Reply 9 years ago on Introduction

    We do have a microphone so you can modulate the carrier. But that part was hand cut. We would have worked up svg drawing to include, but we were pressed for time and we didn't want to mix the parts and we don't have a laser to use anymore...

    Electret mics work well in this well powered circuit, but we really wanted an old carbon mic. I don't supposed you (or anyone ) has a good cheap source for carbon mics? Electrets "hide" some of the magic and we like to "demystify the world around you", show you all the parts and just how simple and understandable it is and can be.


    Reply 9 years ago on Introduction

    Hm -- never heard of a carbon microphone... I wonder if a ribbon mic would be makeable (and if quality's not a concern, would it be easily-ish to do).... Aluminum foil, magnets, and a transformer -- what could be easier? ;)


    On a side note -- what makes this project different than snap circuits? Don't they accomplish the same goal? And they're already purchase-able....


    Reply 9 years ago on Introduction

    I like the ribbon mic. But we wouldn't want to show that in a single symbol since it's make up of several more basic components that we would rather show. Same situation as the electret really. That said, I think it's a great project and we should have the parts to make it for sure!

    The carbon mics are what used to be in old style telephones. They were once plentiful and cheap. Now they are scarce and expensive.


    9 years ago on Introduction

    On a side note -- what makes this project different than snap circuits? Don't they accomplish the same goal? And they're already purchase-able....


    Reply 9 years ago on Introduction

    Snap circuits are awesome, so no difference there ;)

    Actually, we love snaps circuits, but we like the flexibility we get with removable components. A resistor schematic symbol/felt part can have any value, because you plug in the actual resistor/value separately. So if you only have 3 resistor parts but need them all to be 10k resistors, that's no problem with feltronics.

    Also we're big on no hidden stuff (we'll build to that not start with it). So if you want to build a radio in Snap Circuits you add some resistors, a battery a capacitor, etc and then plug in the FM module. You should be building the module. Now there are obvious reason to have a module, but that's just not where we want to start.

    And the two work well together. This is a large format kit, so you can do it on the whiteboard at the front of the classroom, and the kids can follow along back at there desks. Or they can come up and share what they did individual by building the circuit for everyone to see with Feltronics.


    9 years ago on Introduction

    Very nice Instructable, I'm going to build a kit for my refrigerator! Do you get Felt burn after making so many components?


    Reply 9 years ago on Introduction

    Hehe, no felt burn but you do get very attached to the pieces. It makes it hard to give them away or sell them, and the real value is getting them in the hands of people that will use them to play, and learn, and teach.