I have made and posted a few soft circuit projects but I have often found it difficult to get some of the components needed since there are no stores (that I know of) nearby and shipping to Canada can be overly expensive. So I try to make do. One problem I've had was finding something to use as an on/off switch. I've improvised by using switches from LED tealights which are a bit obtrusive in a soft circuit. I've also made some momentary switches ( is that the right term?), which are a bit annoying since the circuit only stays on as long as you press the switch.
So in this instructable I made a switch that stays on without having to keep pressing on it as well as have it look inconspicuous in a soft circuit project. As a bonus it not only turns a circuit on and off it can toggle more than one circuit. In the sample circuit I made to demonstrate you can switch between three LEDs.
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Step 1: What You Will Need
Thread: You will need some thick thread since the button will likely get a lot of wear and tear. I used embroidery thread.
Conductive Material: You basically need something that you can attach to the bottom of the button to make contact with the conductive thread of the circuit. You have several options here:
- Conductive fabric: You would just need a small piece of conductive fabric and glue it to the button.
- Conductive thread: You can wind a bit of thread up into a bundle and glue to the button. I often have little scraps of thread left over from projects that I can use for this.
- Copper tape/ conductive tape:
- Conductive paint: You can buy it or make your own.
- Metal: perhaps a small thin piece that you can glue to the button
- Wire: I recently saw icecats' instructable on how to make conductive tape using wires, perhaps this can be adapted for the button switch.
Step 2: Prepare Button
- Cut a small piece of conductive fabric , it should be large enough to be able to bridge the gap in the circuit but not too large that it covers other parts of the circuit.
- Glue the fabric to the button, I used a glue stick, I didn't want to use a glue that soaked into the fabric in case it interfered with conductance.
- Make sure that the fabric is in a spot that can cover the gap in the circuit. Wipe off any excess glue.
- If you want you can make a line on the top of the button to indicate the "on" position.
Step 3: Prepare Circuit
To test my button switch I made a simple circuit with a 3v button battery, three sequin LEDS, my switch and conductive thread. To make it interesting I made it into a "Mood Indicator", the LEDs indicate what mood I am in, shown by the happy, sad and sleepy face.
For the button switch to be effective you need a gap in the circuit, so when the conductive part of the button is over the gap, the circuit is bridged and current passed through (turning on the LED).
I drew out the circuit below. In image 3 you can see where the gap is (under the button). I also included a circuit schematic, I never made one before so please let me know if I did it wrong.
Step 4: Sew Button
- Use thick thread to sew on the button since it will get a lot of wear and tear as a switch. Don't sew the button on as you normally would on an item of clother (etc.) as you will need this button be able to spin.
- To do this start from the back of the fabric
- Poke the threaded needle through the fabric to the front, through the button hole (make sure the side of the button with the conductive material is facing towards the fabric.)
- Bring the needle through the second hole in the button then through the same hole in the fabric you came out from.
- From the back, tie the two strands of thread in a knot, tightly. You need to make sure the button makes close contact with the surface of the fabric so that the conductive material on the button touches the conductive thread of the circuit.
Step 5: Some Things to Consider
I am a little worried that the thread holding the button on may loosen with time such that the conductive material doesn't make enough contact with the conductive tread of the circuit. The knot may need tightening over time.
I recommend lessening the size of the gap in the circuit, since it is harder to ensure that the area is covered by the conductive material on the button (you need to be more accurate where you turn the button).
It also pays to keep the gap in the circuit closer to the centre of the button, since that is where there is the most tension keeping the button close to the fabric.
Please feel free to leave any comments, suggestions or criticisms about my button switch. Thanks!