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Wednesday, September 18, 2019

Buffer or Unity Gain Op-Amp

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. Buffers are used as interface between circuits. Low impedance of an output means it can source sink lot of current, when you need 2 opamps use LF353 or TL072 which are dual opamps.

Buffer or Unity Gain Op-Amp 

There is an Interactive Tutor in the above linked page. it has Virtual Meters and Pots, shows how a Unity Gain Buffer Operational Amplifier works. When no gain is required and you need to match impedance this can be use. Front end amps, Sensor amps. Polarity Inversion in Analog Computing or Signal Conditioning.

Buffer or Unity Gain Op-Amp

Vout = -(Vin) for inverting

Vout = Vin for non-inverting

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.

More at Analog Op-Amp Circuits

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