Making your own LED poi - PART 1 "selecting led's and power source"This is what I know about LED's and their construction for using them in poi or other equipment where knocking and high impacts can occur.
Note: "Photon" lamps are LED's
LED (light emitting diode) is an electro-chemical light as opposed to a "normal" light bulb. A "normal" light bulb cannot take much impact as the small thin resistive wire, that heats up to produce the light, can break easily.
In a LED there is no small thin resistive wires but two plates with three layers of chemicals in between them. When an electric current is passed between the plates light is produced. These plates are placed within a solid resin capsule to protect and house them. This capsule is available in a number of shapes/packages. The ones used in the "LED light stick" are 5mm Round. Others are rectangular, square, 10mm and 20mm round. LED's have a life of 50,000+ hours and are much much more efficient than a "normal" light bulb.
The best type to use for making in a set of poi are the "ultra bright" ones that appear clear in colour. These generally have an output of about 3,400 MCD (milli-candella) to 12,000+ MCD
The best value for money when purchasing are the 5mm clear round LED packages.
You can now even get Ultra-violet LED's which are great for showing off fluorescent colours.
Before selecting a LED you must first decide on what batteries you are going to use and what voltage you will then have available.
You will need at least a 2 volt supply to run a LED. So either use 2 single cell batteries (ie 2 x AA, 2 x AAA etc) or a single multi cell battery (3V,6V, 9V, 12V etc)
You will need at least a 3 volt supply if you wish to have a high frequency flashing circuit for the light output. However a 6volt supply means you can make a simpler and cheaper flashing circuit.
Some LED colours and high brightness require higher voltages. Check the LED specifications when looking for operating voltage range.
Batteries will be the heaviest part of your poi set so this too will have to be considered when deciding your power source.
Each LED will use 20mA of current so two 1500mA/h size AA batteries in series (3volts) should run a single led for about 75hours.
Ten LED on the same power source will last for 7.5 hours.
Making your own LED poi - PART 2 "construction and protection of components "Here we will look at some techniques use by manufacturers to encase and protect the fragile electronics inside.
Astroball and Astropoi. 63mm diameter. Material PVC.
9Volt replaceable battery supply. A simple square printed circuit board with a rectangular hole where the battery passes within the ball. Two ultra bright LED's also mounted on the board.
The PVC body does have some flex in it. The 9Volt battery provides power, rigidity and strength to the ball and printed circuit board. Without the battery inserted the ball may flex too much and cause the circuit board to be bent and possibly break. If you use the Astro poi make sure you always have the battery inserted even when practicing during the day.
All components are kept rigid and supported to some degree by the battery and PVC material to reduce movement of components that can lead to breakage.
Glow Ball/Laser Balls. 68mm diameter. Material PVC Plastisol.
Internal rechargeable battery supply. A simple square circuit board with an attached charging socket. The white heat shrink tubing covers the battery and is situated below the charging socket. On each side of the battery are two ultra bright LED's (total of 4 LEDs).
The internal PVC plastisol is clear in colour and contains and protects the internal components. An external PVC coating is coloured and captures the LED light uniformly.
Again, all components are kept rigid and supported to some degree by the PVC material to reduce movement of components that can lead to breakage.
Beaming poi (No longer Available). 68mm diameter. Material ABS JSR12.
Replaceable size AA battery supply. 2 Piece complex light weight hollow ribbed construction. LED's connected with flexible multi strand wires. 4 ultra bright LED's.
Wire ends, resistor and LED's are individually coated in additional resin to prevent movement of components that can lead to their breakage.
Another common lighting means is to have a small LED light circuit in a bag packed with clear plastic beads. Similar to a hacky sack or foot bag. The circuit and battery is protected from movement and impact by the plastic beads, and the circuit is held rigid by a small strong plastic inner shell. I did have a picture of one of these but could not find it for this page.
As you can see by the above designs the biggest concern is breakage of components which is generally caused by flexing of components. The more rigid the case of the circuit the better the rigidity of the components. The more protection the better it will handle impact.
Here are some other LED items people have used for swinging.
The Krill light shown to the right (runs on 2 x AA batteries) is made from a Polycarbonate (very strong) material and is supposed to be "bullet proof" and can take many knocks, but has not had internal components secured for repeated impact.
The photon lights (runs one LED on 2 x button cells) are made from a glass fiber reinforced plastic but again the components are not secured for frequent impacts and can be damaged over time (but a bit of resin around the circuitry can fix all of this).
Making your own LED poi - PART 3 "flashing circuits"Important notes about flashing circuits.
You can flash the LED on/off/on etc at normal current 20mA but you will find that if 50% of the time it is on and 50% off the LED will appear only half as bright as you increase the frequency.
For a higher frequency flash (eg 1000Hz or 1000 cycles per second) you are better to have a circuit with the LED having 5 times the forward current for 1/5 of the time.
So for 1 milli-second the LED will be on at 5 times the normal current (eg 100mA) and hence extra brighter than normal. Then for the next 4 milli-seconds the LED is switched off and able to cool back down before switching back on and repeating this process again. this will mean you will not loose any brightness from flashing.
I hope that gives you some ideas in designing your own LED lighted poi .