Inverting operational amplifier circuit won't work

In summary: What he should have done is to extend the black wire of the right battery to the breadboard. Then he can just connect the red wire to the breadboard.Yes, I am using this circuit.
  • #1
gothloli
39
0
I'm making a simple circuit on the breadboard with a 741 op amp. The feedback resistor is 150 kohms, and the input resistor is 100 kilo ohms, means the gain is 1.5. The input voltage is about 5.33. The power supply is ±18 V. For some reason the output voltage is 0.98 V instead of the amplified voltage. Also when I try the LF356N it doesn't show any output voltage at all.

Below is a picture of my circuit
 

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  • #2
I can only see three batteries. How are you getting +/- 18 volts?

How are you getting 5.33 volts input? I can't see any divider resistors. I would make this 1 volt for test purposes anyway.

The red wire on the top battery doesn't seem to go anywhere.

Are you using this circuit?

images?q=tbn:ANd9GcQD70c1nUYza0Ed6zb6IPRKS1YZSqSrOaxcPkzstrbafsl0wpMe.png
 
  • #3
yah I'm using that circuit.
But the battery I used for the input signal is 5.33 because I burnt it out, because I don't have 1.5 volt batteries around
 
  • #4
Do you have a meter?
 
  • #5
I don't see any connection between the midpoint of the two supply batteries, pin 3 and your input's "zero" side. Those three things need to be connected together.
As has been pointed out, your supply only seems to be +/-9V. That should be just about enough though.
 
  • #6
gothloli said:
yah I'm using that circuit.
But the battery I used for the input signal is 5.33 because I burnt it out, because I don't have 1.5 volt batteries around

No, you're not using that circuit (inverting amp). You're using this circuit. Its a non-inverting amplifier. Gain = 1 + R2/R1 ( = 2.5 in your case)

op-amp_basic_non_inv.gif


Also give the circuit a common ground by connecting the middle of +-18V battery to the negative terminal of your input. (i.e. at the other end of the resistor you took out from pin 2)
 
  • #7
gothloli said:
I'm making a simple circuit on the breadboard with a 741 op amp. The feedback resistor is 150 kohms, and the input resistor is 100 kilo ohms, means the gain is 1.5. The input voltage is about 5.33. The power supply is ±18 V. For some reason the output voltage is 0.98 V instead of the amplified voltage. Also when I try the LF356N it doesn't show any output voltage at all.

Below is a picture of my circuit

I look at you breadboard. The top battery is supposed to be the input voltage. The black wire is connected to the 100K which connect to pin 2 as input. Problem like Vk6kro said, the red wire of the battery is not connected to the breadboard! If I see you picture correctly, you are not going to get anything meaningful out of this. I can't see where the clip on the black wire goes to as your picture don't show. You need to have connection to the ground reference to establish the potential. The ground reference is the junction of the red wire of the lower battery on the left side and the black wire of the lower battery on the right side. You have no connection of the ground reference to any other points.
 
Last edited:
  • #8
vk6kro said:
I can only see three batteries. How are you getting +/- 18 volts?

How are you getting 5.33 volts input? I can't see any divider resistors. I would make this 1 volt for test purposes anyway.

The red wire on the top battery doesn't seem to go anywhere.

Are you using this circuit?

images?q=tbn:ANd9GcQD70c1nUYza0Ed6zb6IPRKS1YZSqSrOaxcPkzstrbafsl0wpMe.png

He has only +/-9V. He used an empty clip to hold the red of the left battery to the black of the right battery.
 

Related to Inverting operational amplifier circuit won't work

1. Why is my inverting operational amplifier circuit not working?

There are several possible reasons why an inverting operational amplifier circuit may not be working. Some common causes include incorrect wiring, faulty components, or incorrect values for resistors or capacitors. It is important to double check all connections and values to ensure that everything is correct.

2. Can a damaged operational amplifier cause the circuit to not work?

Yes, a damaged or faulty operational amplifier can prevent the circuit from functioning properly. It is important to check the amplifier for any signs of damage or malfunction and replace it if necessary.

3. How do I troubleshoot an inverting operational amplifier circuit?

The first step in troubleshooting an inverting operational amplifier circuit is to check all connections and values for accuracy. If everything appears to be correct, you can use a multimeter to measure the voltage at different points in the circuit to identify any potential issues or faulty components.

4. Can using the wrong power supply affect the performance of an inverting operational amplifier circuit?

Yes, using the wrong power supply can have a significant impact on the performance of an inverting operational amplifier circuit. It is important to use the correct voltage and ensure that the power supply can provide enough current to meet the circuit's demands.

5. Is it possible to fix an inverting operational amplifier circuit that is not working?

In many cases, an inverting operational amplifier circuit can be fixed by identifying and addressing the underlying issue. This may involve replacing faulty components or adjusting values for resistors or capacitors. However, if the circuit is severely damaged or the issue cannot be identified, it may be necessary to rebuild the circuit.

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