DIY 42 LED Hula Hoop
Updated Feb 28: See my website for better pics and wiring diagrams.
42 led's in 1 hoop. With the flick of a switch you can have 21 led's of one color scheme, then flick to the other and have 21 led's of another. All inside a 3/4 inch pipe for faster hooping styles.

I started learning about this because my GF wanted a LED hula hoop for christmas. After seeing sites online selling them for $250+ for rechargeable ones.. I decided i could make it myself. Thanks to the tutorial on here and prodmod for the inspiration.

see more pics and videos of these on my site, ledhulahoop.com

purchase items needed or custom made hoops, ledhulahoop.com

Step 1: Supplies

Here is a list of supplies you will need. All my prices are in Canadian funds. You can get things a little cheaper from ebay and such. But this was all bought from local plumbing and electronics stores.
Supplies List
42 LEDS - $25.00
132" of 3/4" pipe - $20.00 for 20 ft.
1 x 3/4" pex coupler - $1.00
2 x 3/4" pex clamps - $0.50
60' x 22 ga Wire - $15.00 for 100 ft.
4 x AA NIMH rechargeable batteries - $18.00
1 x 6 volt battery charger - $15.00
1 x 1.75 x 4.75mm plug and dc Jack - $4.50
36 x 68 ohm resistor - $2.00 for 100
6 x 150 ohm resistor - $2.00 for 100
1 x Slide Switch DPDT on-off-on - $$9.00 for 10
1 x 22ga male and female tab connectors - $3.00 for 10 of ea.

Everything comes to around $80 - $85

Plus a few basic tools you may already have.
Tools List
Soldering Iron, Drill, Solder, file or sandpaper, Flux, Electrical tape, marker, glue, pipe cutter, String, Wire strippers, Bubble wrap, and a paper clip.

Step 2: LED and Resistor Information

Resistors are basically used to drop the voltage so you don't fry the LED or draw more power then it needs.
Each LED requires a different voltage to light up. Some 2.4volts, some 3.6volts and so on.
Using OHM's Law, i calculated that with 4.8 Volts (4 x AA Rechargeable's). I needed 68 ohm resistors for the 3.6 V led's and 150 ohm resistors for the 2.4 and under LED's.
Some people use exactly 3.6 volts, lithium or 3 AA batteries. But as soon as the batteries start dieing they lose voltage and some LED's won't light up as bright or at all.

Here is theResistor Calculator Resistor Calculator. Pretty simple. Supply voltage is 4.8volts. Voltage Drop and Desired LED current is how much the LED needs. I will be posting how much each led needs on my site. And how many in the line.. so 21 or whatever.

Soldering the resistor is very easy. You can put the resistor on either the negative or the positive. It doesnt matter. I used the positive. Usually on a LED, the positive is the longer of the 2 leads. I cut my positive leads before soldering, to make the length of each almost the same after i solder the resistor.

Step 3: Soldering Batteries

So I started the process by soldering all my batteries together in series. Basically negative terminal goes to the positive on the next battery. I wanted to evenly distribute the weight around the hoop so I separated the batteries by 31-36" of wire, so i had some extra to play with. I created a little video to show you how easy soldering a battery is. . WARNING! Soldering batteries is very dangerous and they could explode. Try at your own risk.

Soldering Batteries.
Prepping the batteries. I have used many different kinds of batteries. This time i am using Venom 2400 mah batteries. I start off by charging them. Them I take my cheap nail file and scratch up the tops and bottoms. Just so the solder has something to grab onto.
Since my hoop is 132, batteries are 2 and i need 4 of them. I need to have etleast 31 of wire in between each battery. So i made it 32s just to be safe.
Strip each end of the wire.
Put some FLUX on the battery end and the end of the wire. It acts as a bonding agent for the solder and makes soldering soooo much easier.Put a big glob of solder on the soldering iron. Touch your wire to the battery and push the soldering iron on top. It shouldnt need to be help on ther for more than 5 seconds. Remove the iron, and blow on the solder. It should harden and you will be able to pick the battery up with just the wire. If it falls off try again.

Step 4: Battery Charger Plug and Jack.

I changed the plug for the battery charger to a 1.7 x 4.75 mm plug. So the Jack could be more inside the hoop and less exposed. So I soldered the positive wire to the middle and negative to the outer. It will be the same for the jack hole.

Step 5: LED Wires

I purchased 1 spool of red 22 awg wire. So to distinguish the positive from the negative i took a marker and ran it down one length of the red wire. So now it has a black line on it to show it is the negative.
I bought a second spool of white for the DUAL. So i could distinguish the different LED strings.
(in hind sight, use the same color for the led wires, and a different color for the battery line.)

Next run the wires for the LEDS, Positive and ground. Mark out where you want the LED's and the batteries to go.
For 21 LED's per length of 132" wire. It was about 6.5 inches in between each led.
Make sure you leave enough room between the LED's for the batteries, no soldering or tape or they wont fit in the pipe.
Solder your resistors to your longer part of the LEDs.
And then solder the resistor to the positive wire.
Solder the other line of the led to the ground.
Tape up your exposed wires. And tape the wires together. Move on to the next led.

Always test the string before you move on to the next step. You can use a 9 volt battery to make it easier. Just touch the positive string to the small port and the negative to the pole with the folds.

This step take the most time. Took me about 3 hours, taking my time. Soldering the resistors, soldering the 42 led's to the 2 lines, tapeing everything up.

Step 6: Bubble Wrap Wires

After you are done soldering, you want to attach all the wires together. Both led lines, the battery line and some string.
To make things a little easier. You can attach the Ground wire from the batteries, to the ground wires from the LED's.
See pic
Then you wont need to have any wires going across the opening in the hoop.
After all the lines are attached together. You want to bubble wrap between the batteries. To make the hoop quieter. And protect the led's.
Remember you want the batteries to be able to slide through the pipe. So only bubble wrap the led's and wires. leave that batteries exposed.

Step 7: Switch and Jack Placement.

Next I drilled the holes for the switch and the dc jack. You want to place them far enough back that you can still get the coupler all the way in. I used a 1/4" drill bit. 1 hole for the dc jack, 2 holes for the switch and just ran the drill back and forth till it made one long hole for the switch to fit.

In the pic i used a spare section of pipe just to test the placement.

Step 8: Pull the Wires Through the Pipe.

I attatched another piece of string to the string tied to the lines, in the bubble wrap. At the end of that string i attached a battery for weight and slid it trough the pipe. Grabbing that end of the string now i pulled the lines through the pipe. carefully and slowly. helping each battery to enter the pipe.

After the wires have been pulled through. The only wire that should be going across the un-connected hoop is the positive( or negative depending which way you have the batteries facing.). So I put a male and female connectors on there just too easily connect it when I am ready to clamp it closed. (see pic)
Or if you connected the negative battery wire to the LED's no wires should be going across the gap.

Using a bent paper clip similar to the other led hula hoop instructions. I pulled the LED wires through the switch hole. And the positive and negative through the Charger/dc jack hole.
I connect the wire that will be from my battery positive and negative to the dc jack for the charger.
Then the positive goes from the jack to the middle pole of the switch.
Since my switch is a on-off-on DPDT switch
Then on either side are where the positive led wires go.

Pictures can't really show what is happening so ill draw a pic.

Step 9: Finishing and Connecting the Pipe.

After connecting and soldering all the wires. I put glue around the outside of the switch and DC Jack. Then pushed them into the pipe.

Now there is 2 ways to connect the pipe. permanent or collapseable.

Permanent:
Since I didn'tt want to buy the $200 tool needed for the pex clamps. You can just take your finished hoop to home depot and they will let you use their rental tool for free. Or you can rent it for $8 / day.

Collapseable:
I clamped one side and then on the other side used a gear clamp.
There are some pics of the collapsed hoop compared to the permanent hoop.

Taped it up for asthetics and safety.
Done!
On my site i sell the DIY kits with all the items needed.
Or if it is too much work i also sell cutom made hoops. Check it out.

LED Hula Hoop