Bruce Glazier
New Member
Hello,
Looking for some advice on the forum again since I had really useful help the least time I posted. The scope picture (Picture 3) is at the output of Picture 1 on C36 with no input connected, inputs being C28 (Tx+) & C29 (Tx-) and also C30 (Rx+) & C31 (Rx-). This noise is present on the output and I can't seem to figure out what is causing it. Picture 2 is the power circuit, which takes +12VDC in and creates the +5V and -5V rails for the op-amps. The IC is a MAX660ESA (https://pdfserv.maximintegrated.com/en/ds/MAX660.pdf). I had managed to eliminate some noise on the rails by connected FC to VCC which switched the MAX660ESA to operate in 40KHz mode instead of 10KHz mode.
Also, FYI, the notch filter portion is not my design but it is a design taken from a working module so any ideas about what could be changed there would be appreciated because I honestly have a hard time wrapping my head around it.
Thank you for any input and I am open to answer any questions.
-Bruce