Giant 555 Timer Chip Backpack

For the aspiring engineer, make this cool integrated circuit shaped backpack to carry your assortment of little electronic goodies. This can also be used as a debug-out bag with essentials such as a multimeter, 30 watt soldering iron, solder, solder pump, third hand, pliers, tweezers, screwdriver, wire cutters, lockpicking tools, flashlight and a bunch of capacitors and resistors. Suitable for wear at an IEEE convention, hamfest, or kindergarten.

The bag can be a single strap sling across the body type/over the shoulder or strap unzipped to form two backpack straps.

Kids, bug your folks to get you a sewing machine, serger, arduino or the rest of the plushies from Adafruit's Circuit Playground(watch the educational videos and download the coloring book), not necessarily in that order.

CAUTION: Know your machinery before you work with it. No soldering required here but a good skill to learn.

(Halloween Note: Just make the backpack in the shape of a spider, add more legs if needed to be anatomically correct.)

For this project you will need

Black cloth

My outside layer was fleece and a liner fabric of sturdier canvas

Grey/Silver cloth

stiff wire

fabric paint

cardstock

packaging tape

1 inch world wide webbing

long purse type zipper for backpack opening, 22 inches or larger

long separating zipper for sling/backpack straps, 26 inches longer or shorter depending on how long you want the backpack straps

You might be able to get away with some tedious hand sewing of this project but you should be able to zip through it with a sewing machine. Having a serger makes sewing some parts easier.

The size of my backpack was based on the fit of a regular spiral bound notebook. It also happens to be the size of my iPad 3 *cries*

Mark a 3 inch border all around which will form the sides.

I serged together the liner fabric with the outer fleece fabric all around the outside edges.

Mark off where the corners go.

Since it is all flat, now would be a good time to sew applique on a circular patch for the indicator dot.

Working on the inside, Sew off the folded up corner and trim off excess material.

Turn inside out.

You should now have two "trays" or "inboxes" as the top and bottom halves of your backpack.

To make the legs or wire leads that come out of the chip:

Cut up strips of fabric 9 x 2 inches (1/4 inch seam allowance in there)

Sew two layers of fabric to form a U-shaped pocket with the opening at the top.

Turn inside out and shape the corners. Use a dowel, drumstick or chopstick to help push the inside out.

Cut pieces of cardstock that fit inside the tube when folded lengthwise. It will become the leg stiffener.

Cut a piece of wire for each leg. I took apart some 12 gauge household wire cable.

You can use a pair of pliers to loop the ends of the wire so they don't poke through. Form the wire so that it will not be in the way of sewing the top of each leg to the body.

Tape a section of wire into the cardstock stiffener. Cover everything with tape to make it water resistant.

Place inside the fabric tube and trim to below the opening at the end. You just want fabric to sew through when you attach it to the body.

Arrange your legs onto the body.

Sew to the top all around. This seam should also seal the open ends of the leg tops.

I used a 22 inch long purse zipper for the backpack opening. This kind of zipper has two pulls and is stopped at each end. The opening and closing of the enclosure is anywhere you want to drag the zipper pulls.

Find the center of the zipper by just bending in half and match that up to the center of the top backpack opening.

Sew the zipper so that the seam does not show on the finished side. This means sewing on the inside and then sewing a locking seam on the outside to make it lie flat along the seam.

You may have to move the zipper pulls so they don't get caught up by the sewing machine. Close the zipper so it is aligned correctly when sewing in place.

Sew both sides of the zipper to the backpack opening. Work the raw ends of the zipper into the seam by folding them in at the end and sewing over.

Test when finished to make sure the zipper does not get caught in the fabric edges.

Finish attaching both sides of the backpack together by sewing the rest of the open seam closed all around..

I tacked each leg to the side of the body with a couple of stitches to keep them from flailing around too wildly. I think a complete inverted U shaped leg stiffener attached to the body would work better to keep the legs in position.

I used a 26 inch long separating parka zipper.

Cut two lengths of nylon webbing a little longer than your pull-apart separating parka zipper.

Roast the ends of the nylon webbing over some kind of open flame to seal the ends from fraying.

WARNING: Don't do that unless you are a seasoned professional. Melted and flaming nylon is hot and napalmy.

Sew the zipper to your webbing.

Use a zipper foot in your sewing machine so it does not ride up on your zipper causing a jam or break.

Turn over and sew a locking seam so that the zipper will lie flat when opening.

Zip together and sew non separating end to the center top of the backpack.

The bottom two free ends (when the zipper can pull out and be separated) should be sewn to each bottom corner of the backpack.

Reinforce with a bar tack stitch if available.

You need to put some authentic chip markings on the backpack.

You can handletter with paint or if you have access to some kind of cutting machine, create a stencil.

Use the stencil and dab on or brush silver paint.

Since the fabric absorbs paint, it will give that barely legible printing effect as seen on real chips.

Of course, this can be any chip that comes in this type of integrated circuit package, the venerable 741 op amp, ATtiny85 microprocessor, etc...

Make one and take it to your circuit playground.