Spring 2016 3DOT Goliath, Making Laser Tag Possible: The emitter

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By: Kevin Moran (Electronics and Control Engineer)

In this post I will be discussing the IR emitter that is being used to make this game possible, and the components that go along with it:

 

Components:

IR LED: NTE30047

Transistor: 2N2222

Resistors: 8.6k and 110 ohm

 

The NPN transistor acts like a current regulator to ensure the IR LED is provided just enough current. The base which is connected to the 8.8k ohm resistor is connected to a digital pin on our micro-controller (3DoT or Arduino Nano) and this allows us to control when the emitter is on or off. The 110 ohm resistor is connected between the 5V supply and the positive side of the IR LED, while the ground is then connected to the collector.

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This is the resistor value that allows us to use this NPN transistor as an on/off switch.
 

 

Fritzing Diagram:

 

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Eagle CAD schematic:

 

 

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Sources:

Jeffrey Cool: Division Manager

https://learn.sparkfun.com/tutorials/transistors