I am making a active sensor which utilizes an IR LED and a phototransistor. The IR LED would trasmit IR Light and the phototransistor recives the IR Light only if there is a n object near by. Every thing works well except that the phototransistor also detects evironement light. So I decide to modulate the IR signal to 100KH while the phototransistor is to be connectect to a bandpass filter that would allow the 100KH signal to pass. THe problem is that I dont know how to design an active band pass filter that could allow 100KH signal to pass. Could any body pls help me?
Thank you in advance and more power
Thank you in advance and more power