Intro and Background

Fire poi look mighty impressive, but they also have their downsides:

• After spinning you stink of paraffin. I love doing poi, but wandering around for the rest of the evening stinking of the stuff isn't so much fun This is one of the bigger driving factors for developing LED Poi (aside from the fact they look cool of course ).
• It can be dangerous, and there are lots of places you can't do it.
• It's bad for the environment. A tiny drop in the ocean I know, but it's still burning fossil fuels!

In this article, I'll describe how to go about building a set of your very own LED poi - it's easier than you might think!

It's worth noting, there are some other useful guides out there. There's an excellent article on how to build 'Hammer head poi' which describes a very similar method to the one I'll show you here. If you know of any other good guides, let me know

Getting started - What you'll need

If you want to build a set, it's actually pretty simple. Basically, you'll need some batteries, some LEDs, some resistors, a small amount of wire, soldering equipment (or 'chocolate blocks').

Batteries

First off, we need a power source - batteries. I've used both AAA and AA batteries to power my Poi. AA's will last longer, but AAA's are smaller. I use NiMh batteries because they can cope with running lots of LEDs at once, and because they're rechargeable. You can get some that last a seriously long time from Eurobatteries.com. Capacity is rated in mAh (MilliAmp Hours) - the higher that number, the longer your LEDs will stay lit for. The exact time depends on how many LEDs you're using and how you set them up.

To get started, I'd recommend using 4xAAA NiMh batteries. They have enough voltage when you string them together, and they're reasonably small.

LEDs

Next, you'll need some LEDs. I've had some pretty decent ones (reasonably priced too) from LED-Lights.co.uk. I used to use four of their blue LEDs (that's what you can see in the photo at the top of this page).

Resistors

If you've got your LEDs and batteries, the next step is to calculate what size resistors you'll need. Without resistors, there will be nothing stopping an enormous current flow through the LEDs This depends on your choice of batteries and LEDs, but the calculation is the same. I could go into detail about this, but Linear1.org has an excellent LED calculator which will do all the math for you!You need 4 values:

• Source Voltage - If you're using NiMh batteries, this will be 1.2v per battery.
• Diode Forward Voltage - Check out the datasheet or the specs for your LED. Using the Blue LED's I mentioned earlier, you should enter 3.4v.
• Diode forward current - Again, check the datasheet. From the same dtasheet as before, you can see it suggests a forward current of 20mA.
• Number of LEDs in your array - I went for four although you could use more or less.

The diagram above shows the output from the wizard with the batteries added. That's a pretty simple circuit really. If you wanted, you could add a switch to turn them on/off. Either that, or just unplug them when they're not in use.

Finishing Up

Once you've connected up your circuit, find something reasonably strong to stick it all in, and pad the batteries to stop them getting smacked around if you hit something. Bubblewrap works very well there.

If this article was of use to you, or you have comments, suggestions, constructive critisism, I'd be interested in hearing from you!