LED Dog Leash

Winter months bring cold weather along with shorter days and earlier sunsets. While this causes me to want to hide in my house under a gigantic blanket, it does not stop my Dad and my 13 year old Cockapoo Toby from going on long walks in the cold after dark.

Recently I was driving home at night and I realized how dark our neighborhood truly is. There are no street lights and cars like to speed up and down the curved roads. While my dad wears a reflective vest so he can be easily spotted by cars, I worry about Toby getting hit as he is not as visible. I made this dog leash as a gift for my Dad to help Toby stay safer on their walks.

If you have stumbled across this Instructable hoping for instructions on how to quickly slap some LEDs onto a dog leash, you have come to the wrong place! Because I believe in doing things the hard way, I am going to show you how to sew your own leash from scratch and embed the LEDs within.

The things you will need are as follows:

1" Nylon Webbing

7/8" Ribbon

Surface Mount LED lights (I used these found on Ebay. They require a forward voltage of 3.3V and are 0.8mm long. I really would not recomend purchasing anything smaller than these. If I had to do this project again, I would probably by larger SMD LEDs.)

Surface Mount Resistors (I used size 0603 120 ohm carbon resistors found on Ebay. Again, I would not use anything smaller than this.)

Conductive Thread

Sewing Thread

Crimp Beads

Coin Cell Battery Holder with On/Off Switch

2x CR2032 Coin Cell Batteries

Large Clasp

Beeswax (I used this nifty thing)

Clear Nail Polish

Lighter

Tweezers

Goop (or comprable glue/adhesive)

2 Sewing Needles

Pins

Scissors

Solder

Soldering Iron

Sewing Machine

In order to attach your LEDs and Resistors to your dog leash you will have to attach crimp beads to them. This will allow you to sew them into your circuit using conductive thread. Surface mount LEDs and resistors are great because they are extremely small, but this also makes them very difficult to work with.

Before you sew anything, you will want to prepare your LEDs and Resistors. For each LED you will need two crimp beads(one for each terminal). For each resistor you will also need two crimp beads.

To begin, get some solder on the tip on you soldering iron. Pick up a crimp bead with your tweezers and put some solder on the end of the crimp bead. Repeat for the second crimp bead as well as for each terminal of your LED. Next, place your LED on a table and push a crimp bead up next to your LED, solder sides pointing towards each other. Hold you LED still with your tweezers and hold the soldering iron to the crimp bead. This will cause the solder on the crimp bead to heat up allowing you to push the crimp bead into the LED. Repeat for the second side. You can solder the resistors using this method too.

Solder more LEDs and resistors than you think you need. If you need 10, solder 20. Because the LEDs and resistors are so small, they are extremely easy to lose. The terminals are also so small, the crimp beads have a tendency to break off if not enough solder is applied. Soldering more than you think you need will save you from going back and having to repair your LEDs and resistors in the end.

Now you will need to cut your nylon webbing to the correct size. To do this, you will have to know how long you want your leash to be. I decided I wanted my leash to be 6' long so I cut approximately 7' of nylon webbing. The extra 1' of nylon webbing allowed for an extra 10" to make a handle, and an extra 2" to fold over to attach the clasp. Cut two pieces of nylon webbing to this size so in my case, I cut two 7' pieces.

To ensure that the nylon webbing does not fray at the ends, take a lighter to finish all of the sides that you cut.

Waxing your conductive thread for this project is extremely important. Conductive thread has a tendency to have lots of little hairs which can easily short circuit your project. Please take my word for this as I had to learn the hard way. I got through most of the stitching for this project and ended up having to redo most of the stitching when I came across this solution.

I bought a fantastic little gizmo from Joann Fabrics which is pretty much a small disc of beeswax inside of a holder with slots which you can pull the thread through. If you have a hunk of beeswax laying around your house (because who doesn't!) you can use that too.

Please note that you do not have to coat all of your conductive thread in wax now. It is something you can do as you work.

Now, take your cell battery holder and cut both of the wires fairly short. Remove approximately half an inch of insulation from the top, and twist the wire into loops. Make sure you can fit a needle and thread through the loops and apply a generous amount of solder.

Using conductive thread take one of the wires from the battery holder, and wrap the tread several times through your loop to ensure that you have a strong connection. With the conductive thread now attached to the loop, begin stitch through the nylon webbing. Stitch until you reach the spot on your leash where you would like to place your first LED. In my case, I chose not to add any LEDs on the handle, so I stitched approximately a foot and a half down the leash. Repeat for the other wire/side. Make sure your wires and stitching are separated by a good amount of space and do not touch.

A trick to working with conductive thread is to coat all of your knots with clear nail polish. This will prevent your knots from coming untied.

To begin sewing on our LEDs we need to determine which terminal is positive and which terminal is negative. To do this, take two sewing needles, and place them through both of the crimp beads. With the battery holder on, poke the tips of the needles into opposite sides of the conductive thread. If the way you have tested your LED shorts the circuit, turn the LED the other way around and it should turn on. The side of the LED touching the black wire is negative and the LED touching the red wire is positive.

Next, sew the negative side of your LED to your nylon webbing. Make sure you wrap the conductive thread through your crimp bead several times to ensure a tight connection. Once your LED is connected, you can continue stitching up the nylon webbing until you get to where you want to attach you next LED. Try to keep even spacing between your LEDs. I used approximately 4.5" spacing between my LEDs, but you can really do whatever you want.

To connect the resistor, tie the crimp bead connected to the positive terminal of your led to a crimp bead on your resistor using conductive thread. Make sure you cut the ends of your not short. Next, wrap conductive thread from the other side of your stitching around the other crimp bead on your resistor and continue stitching up.

Keep in mind, your LED and resistor might not fit completely perpendicularly in between your stitching. Mine typically sat diagonally. Also, if you need to attach more conductive thread at any point, make sure you are using clear nail polish to paint over your knots.

Stitch the entire length of your leash while adding LEDs and resistors all the way. Make sure to leave several inches untouched at the end where you want to attach your clasp.

With the lights turned on, try wiggling your leash around to see if any of the lights dim or if your circuit shorts. If this is the case, you might have a loose connection somewhere, or you thread might not be waxed well enough. Fix everything now because there is no going back from here!

Now, cut a piece of ribbon to the same length that you cut your two pieces of nylon webbing. You can use a lighter to prevent these ends from fraying as well.

Next, pin your ribbon and two pieces of nylon webbing together. The piece of nylon webbing with the LEDs sewed to it should be sandwiched in between the other piece of nylon webbing and the ribbon with the LEDs facing the ribbon.

Using a sewing machine, sew everything together. Begin by sewing down the sides of you ribbon on top of your nylon webbing. You will want to sew as close to the edge of the ribbon as possible so that you don't accidentally sew into an LED or resistor.

Next, fold the side of your leash attached to your battery holder over to create a handle. Sew the edge of your leash (where the wire is sticking through) by hand to the side where it is folded over. A sewing machine will not be able to sew through these wires. To reinforce the connection, use a sewing machine to stitch about an inch up from this point.

The opposite side of your leash is where your clasp needs to go. Fold your leash over through the clasp leaving approximately an inch of material on the back side of you leash. Like you did with the handle, sew along the edge of the clasp, and sew approximately an inch up near the very edge. Remember when you are all done to trim loose threads.

With the battery holder hanging off the back of the handle of the leash, it will be really easy to accidentally pull out. To prevent this from happening, apply a generous amount of glue (I used Goop) to the back of the battery holder and press it agains the back of the leash.

Congratulations, your dog now has a stylish new leash that lights up! Enjoy your walks knowing that your dog is now more visible in the dark.