Dear friends,
I am making an ultrasound signal receiver. The transmitter and receiver is apart from each other about 6 meters. The circuit is powered by a 9v battery. I used three amplifiers from two TL082. The reference voltage (about 4.5v) is generated from voltage divider (two 100k resisters in series). All amplifiers are in inverting input mode. First and second stages are configured as: 10k input resister and 500k feedback resister. The signal output in the second stage is very good. However, the signal from the third stage (input res.= 10k, output res. = 200k) is significantly corrupted by noise. Please give me some advice to clean up the amplified signal.
Thanks,
Zhi Yang