Introduction: How to Sew an Electronic Circuit
This instructable tells you how to create real electronic circuits using a textile perfboard, (a piece of conductive fabric) instead of a rigid perfboard. You will be able to sew resistors, capacitors, LED's, integrated circuits and many other components. This is a list of what you will need:
- textile perfboard (you can find it on www.plugandwear.com)
- traditional components (not SMD!) like resistors, capacitors, LED's, IC's
- sewing needle
- sewing thread. I suggest shrinking sewing thread, you can find it in embroidery shops or on www.plugandwear.com . It is a special sewing thread that shrinks 30% in lenght when exposed to heat.
- wire cutter (or nail trimmer)
Step 1: Preparing Discrete Components
Let's start to sew a resistor like the one you see in the picture. The resistor has two straight terminals as shown in the picture. Start by bending both terminals 90° as shown. Bend again both terminals at 90° as shown in the picture. Cut both terminals so that their tip is about 8 mm (0.31") long.
Step 2: Placing Discrete Components on Perfboard
Now place the resistor over the textile perfboard with terminals parallel to the metal perfboard stripes and adjust the distance between the terminals so that they are over the metal stripes of the fabric. Then gently insert both terminals at the same time inside the fabric, parallel to the metal stripes. When doing this you must be careful that terminals remain inside the fabric without coming out on the back of fabric. To obtain this insert terminals parallel to fabric. See pictures and explainations.
Step 3: Sewing Discrete Components
Now you can start sewing using shrinking sewing thread. Sew along the black lines around terminals so that they are tightly wrapped. It is suggested also to sew around the vertical part of the terminals. Repeat the same steps for the othr terminal and your resistor is sewn and connected!
Step 4: Preparing IC's
If you want to sew IC's first you'll need to check that their legs have a 2.54 mm (0.1") pitch. As an example we will use a 555 timer that has 8 terminals. Proceed by carefully bending 90° with your pliers all terminals on one side at the same time.
Step 5: Placing IC's on Perfboard
Holding the IC with your fingers carefully insert one side in the fabric, taking care that terminal tips remain inside the fabric. Terminal tips must be parallel to metal stripes. Gently pull the fabric and insert the other side, so that, when you release the fabric, the IC is firmly blocked.
Step 6: Sewing IC's
Now you can proceed by sewing all terminals with the same procedure seen for the resistor. Once finished you should cut out the fabric in between the IC terminals because if not they will be shorted. If you have any kind of 'Spray Seam' or hairspray apply to the area, so that fabric doesn't fray. Proceed as shown here. With sharp point scissors cut a square/rectangular opening being carefull to completely remove all metal stripes and wires that connect terminals. I suggest to check with a tester that there are not unwanted connections between stripes and across terminals.
Step 7: Ironing
Once you have finished your circuit place your iron on medium/high on the reverse of fabric. The shrinking thread you used for sewing will shrink, thus blocking all components tightly in place. You might also hand wash gently circuits after they are properly sewn. Before doing that check that all components you used are waterproof sealed and let the circuit dry for at least 24 hours before turning it on again. Tumble dryer not tested.
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