This phototransistor is one of the neatest electronic products that 100Electronics offers. It uses infrared light to adjust voltage. The more powerful the infrared source is, the more voltage that flows. It maybe old technology, as all of your TV remotes are based on this same process, but it very cool to see it in action and to build it yourself. This phototransistor is shielded and when using the IR LED I was getting very little interference from surrounding lights.This example shows the wiring for the phototransistor. You must use resistors. You will burn out the IR LED if you don’t use a resistor. Also you won’t read anything if you do not use a resistor to ground on the phototransistor. You can find a compatible IR LED here.You can also see an example script to read the values from the Arduino here.Manufacturer: TAIWAN OASIS Manufacturer Part No: TOPS-030TB2 Product Category: Optical Sensor ROHS: Yes Datasheet: Click HereSpecifications Wave Length/Frequency: 900nm Product Type: Photo Transistor Package: RADIAL More Information Same Spec Items – SKU A-1541 Manufacturer TAIWAN OASIS MPN TOPS-030TB2 Can be used with –