Static Circuits
LED Noodle Polarity
Two AA or AAA Battery Power
This simple circuit has just two AA or AA batteries. Each has a voltage of 1.5 volts. When they are configured in series, the voltages of each battery is added together to give a voltage of 3 volts. This is exactly the recommended voltage for the LED Noodle!
Connect the terminals directly to the battery pack. Make sure that the positive polarity is connected to the end with the hole. We used a soldering iron and standard tin-lead solder with a low melting point and that did not impact any of our LED noodles.
Three AA or AAA Battery Power
If we need a little longer battery power, we can upgrade from two batteries to three. This gives us a combined voltage of 4.5 volts (3 x 1.5 volts).
To limit the current, we will need a a 15 ohm current-limiting resistor in series with a battery pack.
It is possible to use slightly different values of the current-limiting resistor. A 10-ohm resistor will give a brighter light, but will drain the batteries faster.
9-Volt Battery
Although they are not commonly used in our labs, in a pinch you can also use a 9-volt battery to light up the LED noodles.
Use a 100 ohm resistor in series with the battery.
9-volt batteries are easy to connect but they don't offer the best value compared to AA batteries.
USB Battery Packs
One great option is to use a rechargeable USB battery pack. These supply 5 volts and because they are rechargeable, they can be used many times over and over.
In the diagram above, we used a 20 ohm resistor in series with the LED noodle to limit the current to about 62 milliamps. This is more than bright enough for most applications. A 50 ohm resistor is also a good option and the battery will last considerably longer, but the LED will not be as bright.