Testing an Inverting Amplifier Circuit with R1 = 10k and R2 = 100k

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In summary, the conversation discusses an inverting circuit with R1 = 10 k ohms and R2 = 100 k ohms. The question arises of whether the voltage between points A and B would be 0.1 V if B is connected to ground. It is mentioned that one can create a circuit with a -0.1 V gain by varying the resistors. The concept of a "virtual ground" node is also mentioned, as well as the possibility of creating a gain of -0.1X with a different resistor ratio.
  • #1
Midas_Touch
I have attached an image of an inverting circuit.

If I set R1 = 10 k ohms and R2 = 100 k ohms, I need to verify if this circuit works or not. Therefore, would the voltage between points A and B be equal to 0.1 V since B is connected to ground? The voltage input is 0.1 volts.

Thank you
 

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  • #2
Why don't you just measure the output?
 
  • #3
Yeah, I did that too. But one of the questions asks us to determine what the voltage will be between those two points.

Also, is it possible to create a circuit with a -0.1 v gain? I would think so, if I varied the resistors.
 
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  • #4
Look at the the node equation for the currents entering the (-) terminal.

i.e. (Vin-0)/10k + (Vout-0)/100k = 0
so Vout = -(100k/10k)Vin
note that the gain is 100/10=10 and the output is inverted from the input.

edit:changed sign
 
  • #5
Midas_Touch said:
I have attached an image of an inverting circuit.
If I set R1 = 10 k ohms and R2 = 100 k ohms, I need to verify if this circuit works or not. Therefore, would the voltage between points A and B be equal to 0.1 V since B is connected to ground? The voltage input is 0.1 volts.
Thank you
Nope. Vab would not be 0.1V. Look for the concept of the "virtual ground" node in your opamp text, and think about what the large open loop gain of the opamp does for you when you close the loop in the inverting (gain = -10X as shown) configuration.

And yes, you can make a gain of -0.1X if you want with this configuration and a different resistor ratio.
 

1. What is an inverting amplifier circuit?

An inverting amplifier circuit is a type of operational amplifier (op-amp) circuit that produces an output that is the opposite or inverted version of the input signal. This is achieved by connecting the input signal to the inverting input terminal of the op-amp and providing feedback through a resistor between the output and the inverting input terminal.

2. How do the resistors R1 and R2 affect the inverting amplifier circuit?

R1 and R2 are known as the feedback resistors and they play a crucial role in determining the gain of the inverting amplifier circuit. R1 is connected between the inverting input terminal and the input signal, while R2 is connected between the inverting input terminal and the output. The ratio of R2/R1 determines the gain of the circuit, with a higher ratio resulting in a higher gain.

3. What are the ideal values for R1 and R2 in an inverting amplifier circuit?

The ideal values for R1 and R2 depend on the specific application and the desired gain of the circuit. In general, R1 should be a small value (in the range of 1k to 10k) to minimize loading effects on the input signal, while R2 should be a larger value (in the range of 100k to 1M) to achieve a higher gain. It is important to choose resistors with appropriate tolerances to ensure accurate and stable performance.

4. How can I test the inverting amplifier circuit with R1 = 10k and R2 = 100k?

To test the circuit, you will need to apply an input signal to the inverting input terminal and measure the output signal. You can use a function generator to generate a sinusoidal input signal and an oscilloscope to measure the output signal. Make sure to adjust the gain setting on your oscilloscope to accurately measure the output signal. You can also use a multimeter to measure the voltage across R2, which should be equal to the output voltage.

5. What are some common applications of inverting amplifier circuits?

Inverting amplifier circuits are commonly used in audio applications, such as amplifying and shaping audio signals for speakers and headphones. They are also used in instrumentation and control systems to amplify and process sensor signals. Additionally, inverting amplifier circuits are used in active filters and in analog-to-digital converters to convert analog signals to digital signals.

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