Buffer Opamps
If output impedance of a point is a high value then connecting another circuit at that point will load it resulting in malfunction or error.A non-inv FET input is the best buffer, for inverting buffer use high R values Using very high R values like 2.2M or higher requires a glass epoxy PCB and guard rings around pin 2, 3 to prevent leakage currents on the PCB reaching the PINs. Also moisture and dust has to be prevented by using RTV coating or Varnish. Use 78L05 79L05 for the dual supply required by this circuit.
Vout = -(Vin) for inverting
Vout = Vin for non-inverting
