A phototransistor apparatus and a method of operating the phototransistor apparatus. The phototransistor apparatus can include a phototransistor, a light source, and a supply voltage associated with the phototransistor. After switching on the supply voltage, the phototransistor can generate a phototransistor signal that is scanned, wherein the supply voltage associated with the phototransistor is switched on later than the light source, and wherein charge carriers in a base area of the phototransistor are reactive to a light pulse from the light source in a currentless state, and continue to react after the light source is switched off. Alternatively, the power supply of the phototransistor can be switched on before the light source is switched off. By delaying the switching on of the power supply of the phototransistor compared to the switching on of the light source, a significant current saving can be achieved.