Step 1: Draw a circuit diagram. Build the circuit on a breadboard using wires and test that it works.
In principle, it is a parallel circuit with two switches.
If you need to turn on two LEDs, use a parallel circuit. Because the series circuit will divide the voltage, making the two LEDs share less than 3V and can not light up.
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The inspiration came from when I saw the print on this fabric. I thought I could use the bus as a switch. When the bus arrives at the house, the first circuit closes and the red LED lights up; when the bus arrives at the park, the second circuit closes and the green LED lights up.
I tested the circuit with a breadboard and wires. But here I only tested the most basic circuit, and subsequently added one more LED and replaced the battery (I don't know who took the original one). It turns out that after testing the circuit you should not replace the components at will, because when after sewing the soft circuit it does not work I can not determine whether it is the component has problems 🥲
Step 2: Start sewing!
the original layout
the modified layout
I first determined the position of the components on the black cloth and drew the connecting lines with a marker. Then I folded the two pieces of cloth together and sewed them. I sewed the three parts of the switch first, and when I added the LEDs I found a better position so I repositioned the batteries to sew fewer threads.
Finally, I sewed on the battery and connected it to the two LEDs and the "cover" of the switch. I'm pretty sure my connections were fine, the positive and negative terminals weren't reversed, but the final soft circuit didn't work. I felt a little heat on the battery, maybe my handling of the conductive fabric shorted the battery, but I couldn't check where the problem was. I hope I can get it fixed in class (I really spent a lot of time sewing it so hopefully it can be fixed🥲).
Finished product
Step 3: Reflection
One of my biggest regrets is that I didn't search for videos to learn sewing skills before I started sewing. The knots I tied by sense felt very unreliable, and when I got halfway through the sewing, I had to sew with the attitude of "let's just keep going if it's already like this". I'm sure I'll figure out how to tie the knot before the actual project (of course, the conductive thread is harder to sew is also a factor).
With no tweezers or pliers on hand, it was difficult for me to use the method shown to help distinguish the positive and negative LEDs. Since I connected the LED and the switch together first, I just had to make sure that the long one (positive) was connected, and the remaining one must be the negative one connected to the power supply. In fact, although I swear I did not make a mistake, when the circuit does not work who knows if there was a problem when determining the positive and negative LEDs?
If your components have polarity (only work in one direction) bend the wires in a way you can remember this direction.
Check the connections with the multimeter, finish the knots with nail polish, and insulate connections to prevent a shortcut (this step was not executed because of the lack of tools and materials).