Op Amp Voltage Follower Operational Amplifier Dual AKA Split Supply

Op amp followers output the same voltage as a signal applied to the + input.

741 op amp voltage follower with dual aka split power supply learning electronics lesson 0031
741 op amp voltage follower with dual aka split power supply learning electronics lesson 0031

Dual or Split supply means that there is both a positive and a negative voltage in relationship to the 0V reference point ground.

Op amps can sink or source current.

If the output is more positive than ground, then the output is considered as being the source of whatever current flows.

If the output is more negative than ground, then the output is considered as sinking whatever current flows from ground.

The output being electrically connected to the inverting (-) input is called negative feedback.

  • When the non inverting (+) input has a higher voltage than what is at the inverting input (-), then the output voltage rises.
  • When (+) has a lower voltage than (-) then the output voltage lowers.
  • (+) input voltage and (-) inverting input being equal, holds the output voltage steady at whatever it is set to at the time.
  • With a direct negative feedback from the output to the (-) input, the output instantly moves it’s voltage up or down to whatever the voltage is at the (+) input.
  • One of the polarity indicator LEDs will light up, depending on whether there is enough positive or negative voltage in relationship to ground.  Typical forward voltages are 2 volts for a red LED and 3 volts for a blue LED.
    1. Red LED lights up when the output is more positive than ground by approx. 2V or more (in the diagram).
    2. Blue LED lights up when the output is more negative than ground by approx. 3V or more (in the diagram).

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