Need assistance with a scaling/offset circuit, followed by an LPF

Thread Starter

Tyler Bradbury

Joined Mar 18, 2015
I am trying to scale a voltage, offset it, and then send it through an LPF with a 1 time constant. I can scale it and offset it appropriately, but when I put it through a passive LPF, thi signal gets messed up. Here is a picture.

Question: I want 0-3.3v analog output. After the first stage, I get that. After my LPF, the signal goes to 1.6V and stays there. Why? How do i fix it? Is there a better way to do this?

Thank you in advance.


Joined Feb 24, 2006
Do you mean that the output is DC at 1.6 volts? If so the corner frequency is way too low. Sounds like a low pass filter that passes frequencies less than .001 Hz.

BTW that image is really crappy and I can't read the component values. You can include images in several formats as long as the are not multi-megabyte bitmap or jpeg files.