Re: amplify 40kHz audio signal using TL082: first two stages are fine, but high noise from the third stage

From: Mark (makolber_at_yahoo.com)
Date: 03/16/05 

Date: 16 Mar 2005 14:52:08 -0800

for_idea wrote:
> 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

How big is the signal at the output of the 3rd stage?

Is it clipping?

Is it random noise you have or an oscillation?

You may need a small pull up or pull down on the output of the 3rd
stage.

Mark

Relevant Pages