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Inverting Amplifier - Op-Amp Circuits


Input Impedance of this module is Ri as pin 2 is at virtual ground, the opamp with feedback tries to maintain pin 2 and 3 at same potential pin 3 is at 0V hence pin 2 is at virtual ground. Clamping diodes protect OpAmp, Rf + Ri is between 5kE and 1ME as an opamp may be able to drive around say 5mA max.

Current into node pin 2 = Vin/Ri if Vin is +ve it raises potential at pin 2, in order to bring it to 0V the OpAmp sucks away the current by turning its output negative the current leaving pin 2 node is also Vin/Ri. Then Vout is given by Vin/Ri * Rf as per V=IR ohms law. Most OpAmps output swings around 1v less than VCC/VDD for full swing use CA3130 this is a FET input OpAmp, and has low bias currents in pico amps.

This is used as a small signal amplifier. Used after the buffer stage. Multiple stages cascaded  for higher gains. An Interactive Tutorial with Simulated Meters and Potentiometers, demonstrating how an Inverting Operational Amplifier functions is far below.

Inverting Amplifier - Op-Amp Circuits

Vout = Vin * (-1) * (Rf/Ri)

Interactive Tutorials using Virtual Electronic Components

Slide the Potentiometers just like you would operate a Sliding Control. Drag the Knob on Pot to increase or decrease the resistance. The Resistance is shown is blue letters and dynamically alters value as you slide the pot.

The mV Source is varied by just moving mouse pointer over the two buttons, no clicking. This reduces finger strain and also you have a long lasting mouse. The mV buttons are special, the variation picks up speed if you let the mouse pointer remain on the button. This is Ramp-up and Ramp-down. This enables you to set it faster with just two buttons.

Finally you have a DVM a Digital Volt Meter that just Displays the Voltage at any Point, this readout value has to be noted down.



Use the "iframe" part in this Inverting Op-Amp xml code

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