Flashlight wristwrap - it's a great first project! You will learn how to enable the flow of electricity, and add small electronic components to your simple circuit correctly. This tutorial will include a few bite-size lessons on electronic components, and how they work. Head on in!
Step 1: What You'll Need...
A quick overview of what you should have handy as you make this wristwrap is shown in the photo above. In the next steps, I'll give a detailed list. Have a look at the photo to get your bearings.
You'll need these items in the following categories:
- Leather goods
- Electric goods
- Common Tools
Step 2: Leather Goods
Here's what you'll need, leather wise:
- scraps of leather for the wrist band
- leather "shoelace"
- small piece of sturdy leather
- heavy duty snaps
Step 3: Electric Goods
The electric component of this project is really what makes it fun. I got these parts at Radio Shack (that irreplaceable store that's closing :(....), Home Depot, and Adafruit (adafruit.com is only online). Go D.I.Y.!!
- LED light
- mini electronic switch
- sewable electric conducting thread, plus needle threader
- copper wire and small copper rivet
- mini jumper cables for testing
- 2032 coin cell battery
Bite-size information lesson
What's the difference between electrical and electronic components?
Basically, electronic components can be arranged in a circuit so that a microprocessor can send signals to direct electricity to the component based on some program. The component itself can also react differently to different signals. Electronic components are also small enough to a part of a device that contains many electronic components - all controlled by the microprocessor.
Electric components don't process electricity - you supply them with a current, and they turn on.
There's nothing to stop you from using an electronic component in a simple circuit - ie, not connecting a microprocessor to our circuit. That's what we are doing here, using an LED, a Light Emitting Diode electronic component in our simple circuit. We will just supply the LED with electricity from a battery, and it will light up. If we used a microprocessor - like the wearable Gemma made by Arduino - we could have the LED light up in different colors, based on some program processed by the microprocessor.
Step 4: Common Tools
Every maker needs these tools! (And most regular people need the hammer.) I'm listing them all so you can fetch them and keep them nearby, ready to use.
- wire cutter
- long nosed pliers
- soldering iron & solder
- protective eye shield
- exacto knife (legally known as X-acto knife)
- skinny nails or leather hole puncher
- T-square and cutting board
Step 5: The Problem - You Want Me to Wear That?!
OK, I've got a confession to make - I wanted to make this bracelet because I have a problem - the so called wearable battery holders are ugly! I'm not going to wear that. It's totally bulky and visible! (they do come smaller and a bit less bulkier, but not good enough for me.)
If we want wearables to work, we've got to take control of the fashion sense, ladies and gents. So, I created a customized battery holder, sleek and slender, to tuck into your wristwrap. Before we build that tuckable, wearable, flexible battery holder, let's have a look at how a coin cell batter draws its power... you need to know this.
Step 6: Coin Cell Battery: +/-
In the photo above, the voltage meter is measuring the voltage of our coin cell battery .... as per packaging, it should be 3 volts.
There are two poles on all batteries - a positive pole and a negative pole. On a coin cell battery, the negative pole is at the bottom of the coin cell battery (the smooth side, with no writing), and the positive pole is on the side of the coin cell. In the photo, the red prong of the voltage meter is touching the positive side of the battery, and the black prong of the voltage meter is touching the bottom of the battery. Viola! The voltage meter reads ~3 volts (ok, 2.928 volts....demand a refund!)
So when we create a custom battery holder, we need to design it so that a piece of wire touches the sides of the coin cell (the positive pole), and another piece of wire touches the bottom of the coin cell (the negative pole), just like the voltage meter is touching the battery. This enables the battery to deliver a 3 volt charge down the wire, and our connected LED will light up.
Step 7: Enough Thinking - Get Started!
Choose your piece of leather. Measure your wrist - I just wrap a small piece of paper around my wrist and mark the length with a pencil. Using the T-square, draw a rectangle on the wrong side of the leather piece with pencil - length of your wrist, and width as you like it.
Cut the leather, using the T-square to guide the exacto knife. (This step should be done by an adult, as X-acto knives are extremely sharp!)
Step 8: Battery Holder
Using your coin cell battery, trace a circle on the piece of sturdy leather. Cut out the circular piece of leather. Cut a piece of the leather "shoelace" that is a bit bigger than the perimeter of the circular piece of leather. Glue the shoelace to the perimeter of the circular piece of leather.
Step 9: Add Battery Holder Wiring
Poke a hole in the center of the circular leather, and another hole near the side, next to the leather shoelace - you can use the hammer and the skinny nail.
You'll need two piece of copper wire, each about 3-4 inches long.
With the first piece of wire, form a semi-circle shape which is the same size as your leather circle. Poke the wire through the side hole, and form the piece of wire to snuggle against the shoelace in a diagonal way, that starts at the hole and goes up toward the top of the leather shoelace. This will ensure that some piece of that wire will definitely be touching the side of the battery - the positive pole.
Take the second piece of wire and insert it through the center hole. Loop it through the small rivet for extra conductivity, and solder the wire to the rivet. this prevents the wire from escaping out through the hole unintentionally..
Step 10: Neaten Things Up
Don't let the wires touch each other, if they do the electricity won't flow - that's called a short circuit. So when the wire come out of the leather, be sure they are some distance apart.
We're going to twist the wire ends into two circles, we'll be sewing the conductive thread through these circles. Twist them twice around - each wire in opposite direction, so they stay apart - so there's little chance the conductive thread will slip out of the loops. Use the long nosed pliers for this step.
Once you have your loops, snip the end of the wires with the wire snipping tool. Feel free to hammer down anything to make it flatter!
Step 11: The Switch
Ok there's a lot of ugly switch out there too, but I found one that is really pretty. All golden and silver colored...but alas, there were no sewable attachments on this switch. I figured I'd solder some on. So I took the sewable parts off the ugly battery holder and soldered them onto each end of the beautiful switch. A girl's gotta do what a girl's gotta do!
Step 12: A Note About Anode
I should have titled this step "A Note About Anode and Cathode", but it sounds more dramatic as is.
Step 13: Lay Out Your Design.....
This is getting exciting!
Put all the pieces in place. Here's my design:
On one end the snaps and the switch, in the middle the LED, on the other end the batter.
Connect the parts with alligator clips.
Push the switch......OMG! the light went on!!
Step 14: Put It All Together.....
It seems daunting at times because you saw that it worked, and you just want to wear it! But alligator clips don't cut the cheese, think chic people.
Do the steps one after the other:
- cut slits where you'll put the sewable pieces of the switch. The sewable eyelets slip through the slits to be under the wristwrap, the switch itself is accessible on top.
- using regular thread, sew the battery holder to the underside of the wristwrap, leaving room at the edge for the snap rivets.
- create a hole or two for each leg of the LED - remember the wire coming from the positive pole of the battery must be connected to the cathode leg of the LED, the longer leg
- sew the circuit using the conductive thread! Follow the diagram you drew in step 7. Whenever you sew through an eyelet, loop the thread around a few times for proper conductivity. Never double back on the thread, as a sewing machine would do when sewing real clothes. Remember the thread is a wire and should be straight.
Step 15: Wear Your Flashlight Wristwrap
Very important step - show off !