A non-inverting operational amplifier

Make a small signal taller

Op amp is short for operational amplifier: a powered circuit that compares two inputs. Negative feedback brings part of its output to the subtracting input. Non-inverting means the output keeps the input sign. Gain is their voltage ratio; clipping limits a requested output at a supply rail. Av labels the linear voltage gain, in V/V: volts out per volt in, before clipping.

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EXPERIMENT BENCH

Change the circuit settings, predict the readings, then check a challenge. These are learning models, with the assumptions explained in each lesson.

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How it works

Ideal 0–5 V amplifier with zero input current and output reaching both rails. Real devices have input-range, output-swing, speed and current limits. This model is not a tested circuit.

Requested Vout = Vin × (1 + Rf/Rg). Vin is signal voltage, Rf feedback resistance, and Rg resistance to ground, the 0 V reference. Feedback voltage = Vout × Rg/(Rg + Rf). It matches Vin only in the linear feedback region.

Difficulty

Build · Observe
Power on at input 0.5 V with both resistors 10 kΩ. Read output 1 V.
Need a hint?
0.5 V; Rg = Rf = 10 kΩ → 1 V
Explore · Adjust
At input 0.2 V, obtain output 0.95–1.05 V without clipping.
Need a hint?
0.2 V; Rg 10 kΩ; Rf 40 kΩ → 1 V
Solve it · Discover the limit
At input 1 V, choose gain at least 6. Observe output clipped at 5 V and the feedback input no longer equal to 1 V.
Need a hint?
1 V; Rg 5 kΩ; Rf 25 kΩ → requested 6 V, actual 5 V

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