21 LED Rechargeable Hula Hoop

DIY 21 LED Hula Hoop
Updated : FEB 28, See my website for more pictures and wiring diagrams.
21 led's inside a 3/4 inch pipe for faster hooping styles.
I previously made a instructable how to make a 42 LED hula hoop. But my most popular hoop on my site is the 21 LED so i decided to make another instructable for this one. It is very similar with a little different wiring.

Background:
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 for half that and rechargeable.

Takes about 3 hours to make

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.

The hardest thing to find is a good tubing product. I wanted to use something that was fairly cheap, came in short lengths and had the proper strength and transparency i needed. The product i found that works best is Aqua-pex. It has writing on it with the brand and specs.. but it won't be noticeable at night , when you will be using a LED hula hoop anyway.

Supplies List
21 LEDS - $12.00 on ebay
132" of 3/4" pipe - $20.00 for 20 ft. Aquapex also available on ebay
1 x 3/4" pex coupler - $1.00 home depot or ebay
2 x 3/4" pex clamps - $0.50 home depot or ebay
36' 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
21 resistors - $2.00 for 100
1 x Slide Switch SPST on-off $$9.00 for 10
Everything comes to around $70
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.
http://farm4.static.flickr.com/3086/3184154764_7029162aae_t.jpg

Comments

[lherrera4]

2 questions: im under the impression that the charge current needs to be about 150% of the battery's capacity (4.8V*1.5=7.2V). Could you please explain how you determined the 6 volt charging current?
2nd, using this charger, about how long does it take to charge the batteries? (ok maybe 3 lol) and is it a smart charger (changes current applied) or normal (constant voltage applied)?

[mrboring]

I'm hoping you still check this. I know it's a 6V output, I can't read the amperage. Any more details on what to look for will help.

[danny_01]

think this is a great design would it be possible to put a micro controller so the LEDs could have a few chase's on a button ?

[mwilson39]

"I attached another piece of string to the string tied to the lines, in the bubble wrap." .... Does that make since? Are the batteries suppose to be attached on there own wire? Negative and postive? Do I attach the led wire and the battery wire together?? What do I do??

[mwilson39]

Okay so I am hooking up all my LEDS with the correct resistors and the first one is blue and it worked . I added a few more and now the blues ones do not work, but the yellow and green ones work. Whats going on ? It is getting frustrating :( I just want to finish and hoop it up!

[the Hydra]

Why do you solder a resistor for every LED? Why not just wire all the LEDs in series and place a large enough resistor at the front of the circuit? Then you'd only have to connect the last LED to ground as well. Seems like it would save a lot of time. Yeah, if one LED went down it would shut down every one after it (like older Christmas lights when one bulb is taken out or blown and the rest of the strand goes dark). LEDs are very versatile and long lasting though, so I don't think you'd have to worry about that too much.

[sparr]

One LED dying turning off the circuit isn't the problem. The issue is when one LED shorts out (the other kind of death). That would increase the current to the rest, so another one would short out sooner, which would increase the current to the rest... Not only does it stop working, but you actually kill all 21 LEDs.

[the Hydra]

In the rare case that the LED would end up shorting (mechanically breaking inside the LED housing and actually creating a short circuit), you would see the LED that was out. It would take a lot less time to unsolder that LED and re-solder in a new one to take it's place then it would for you to solder a resistor and a ground wire to every LED that you want to use. Plus, even if you have them wired in parallel you still have the chance that an LED will short in the same manner in which case you are going to want to replace that anyways. So I really don't see much justification for wiring them in parallel instead of wiring them in series. Yea, the light at the end technically wont be as bright as the one in the beginning but there is no way you will see that difference with the naked eye.

[agr00m]

Soldering the LEDs in series would require a MUCH greater power source. Essentially in parallel you only need the source to be big enough to power a single LED, in series the voltage required is added, so 20 3.6v LEDs would require a 72v power source.

[the Hydra]

you're right. My brain apparently was shut off then lol. It would be nice to find something to just use as a ground rail and a power rail that you could use to wire the resistors and LEDs between instead of running individual wires.Obviously you would need to isolate the two rails from each other. But yea, definitely need them in parallel otherwise the voltage requirement goes through the roof.

[agr00m]

Oh, actually the schematic is for a 2 circuit setup. Two power rails and a common ground rail, each with it's own switch. I think the rechargeable diagram link is bad, the URL is too long to fit in the box...hmmm.

I had to break it up into 3 lines, so just piece it together :)
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B_uJZZ1yX4MCNDcxYjFjOTMtMTY
1Mi00N2JmLThhYjAtMDc0YTc4OTEzMDYy&hl=en_US

[agr00m]

Maybe I've got the wrong idea of what you're saying, but I think that's what he is doing, or if not that's what I do. I take a length of paired 18 awg speaker wire, pull the two apart and use one as my ground rail and the other as the power rail. In his instructable a 3rd is needed to wire all the batteries together. Here are two diagram I made a while ago to help a friend with wiring a hoop. The first is a schematic for a regular, non-rechargeable hoop and the second a hand drawn diagram of the OPs rechargeable setup. The one in the instructable was a bit confusing so I "tried" to clean it up a bit.

Standard diagram
https://picasaweb.google.com/117660769616171838596/LEDHoopTutorial?authkey=Gv1sRgCJ-_lIfkipHyDg#5620483850003965250

Rechargeable diagram
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B_uJZZ1yX4MCNDcxYjFjOTMtMTY1Mi00N2JmLThhYjAtMDc0YTc4OTEzMDYy&hl=en_US
(looking at it now I should have at least used a ruler...hehe)

[the Hydra]

Hmm, must have changed since I read it two years ago lol. When I read it two years back it said to run an individual wire to each LED/resistor pair. I'm too lazy to re-read through it, but judging by your response I am guessing that is not the case anymore. Thanks!

[eschuhrke]

how long does your hoop keep its charge with all leds on?
i have a simular design and i have trouble with time of use.

[dhackney]

battery negative?

[shaymorgan1]

I just bought some of the white pex tubing from home depot to make hulas before I saw this site. Is the tubing you are using clear? Will the led show thru the white pex?? I have included a link to a photo of the pipe I purchased.

http://www.homedepot.com/h_d1/N-5yc1vZ1xiu/R-100139315/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

[dog812]

Hey  sorry i havent checked this in a long time everyone..

The pipe is called Aquapex, not available at home depot. Depending where you are located, here in vancouver Andrew Sheret carries 20 ft lengths. Also check ebay. They have 20 ft - 300 ft lengths.

[metajessica]

What happened to your website? I bought a kit from your website about a month ago, but now it is redirecting to SuperHooper.org with no instructions or kits.. Bummer. I love the hoop I made from the kit. On an unrelated note, I remember seeing somewhere that you can not charge the hoop for more than a certain length of time. I accidentally left it plugged in for approximately 20 hours now and it no longer works. Any advice?

[lightedlifestyle]

you can find similar kits with instructions at prodmod.com

[rooster8d]

were can I get one of these Chargers??? Thanks in advance

[dog812]

Any Radio control shop should sell 4 cell chargers. Or i can sell yah one.. email me through my site.
http://ledhulahoop.com

[the_mad_man]

my dad just walked out about 1 minute ago, and he said that coloring the wires with a sharpie is a bad practice (he's an electrician). but, my dad is the kind of person who goes on for EVER if you get something wrong.

[dog812]

I agree that buying 2 seperate colors is easier to work with.. but this is supposed to be on a budget, and we are talking about AA batteries here , not anything dangerous.

[the_mad_man]

yeh. suppose so

[joejoerowley]

Nifty.

[dog812]

If anyone has any questions or comments please feel free to email me through my website.
LED Hula Hoop