Input to amplifier with LPF not working
You show a range of values for your LPF. If R=10k and C=0.2 uF, then the cutoff frequency of your filter is about 80 Hz.  Most of the energy generated by your noise source is well above that frequency.  If you set R=1k and C=0.02 Uf, then the cutoff frequency rises to about 16 kHz and you should see a considerably larger signal. Also your 10k pot will load the output of the LPF and also reduce the available signal.