- #1
bphui
- 7
- 0
The output voltage of op amp is greater than the power supply voltage (+/- 5V). Is Op amp burned out?
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Discussion Overview
The discussion revolves around troubleshooting an operational amplifier (op amp) that appears to be outputting a voltage greater than its power supply voltage. Participants explore potential causes, configurations, and the implications of the setup, focusing on both theoretical and practical aspects of op amp behavior.
Discussion Character
- Technical explanation
- Debate/contested
- Experimental/applied
Main Points Raised
- Some participants suggest that the op amp may be burned out due to the output voltage exceeding the power supply voltage.
- Others inquire about the configuration of the power supply and whether the voltmeter is correctly connected to the output.
- One participant mentions that the output cannot exceed the power rails without an additional power source influencing it.
- Concerns are raised about the circuit's time constant due to the use of a 100MΩ feedback resistor with a 0.22μF input capacitor, which could lead to stabilization issues.
- Participants request clarification on the schematic, specifically regarding the connections to the power supply and the reference ground for the voltmeter.
- There is a suggestion to check the difference between the high and ground voltages with a voltmeter.
Areas of Agreement / Disagreement
Participants express varying opinions on the potential causes of the issue, with no consensus reached regarding whether the op amp is definitively burned out or if the problem lies in the circuit configuration or measurement setup.
Contextual Notes
Participants highlight the importance of correctly referencing ground in a split supply setup and the implications of circuit components on the stability and performance of the op amp.
Who May Find This Useful
Individuals working with operational amplifiers, circuit design, or troubleshooting electronic components may find this discussion relevant.
- #2
BiGyElLoWhAt
Gold Member
- 1,637
- 138
Probably. Have you tried replacing it?
Is it of the order of one of your input voltages?
Is your volt-meter or sensor hooked up to v out and not to your inputs?
Do you possibly have it set up as +10/0V as opposed to +/-5V?
Is it of the order of one of your input voltages?
Is your volt-meter or sensor hooked up to v out and not to your inputs?
Do you possibly have it set up as +10/0V as opposed to +/-5V?
- #3
bphui
- 7
- 0
Yes, I have replaced it and the result is still the same.BiGyElLoWhAt said:
I also set the power supply to +5/0V, the output has negative voltage too.
I am connecting charge amplifier with pvdf film.
- #4
BiGyElLoWhAt
Gold Member
- 1,637
- 138
What are you referencing as ground on your voltmeter? Is it the ground off of the power supply?
- #5
BiGyElLoWhAt
Gold Member
- 1,637
- 138
Also, check the difference between your high and ground with a voltmeter.
- #6
bphui
- 7
- 0
Ground the negative terminal of op amp.BiGyElLoWhAt said:
- #7
berkeman
Admin
- 69,479
- 25,006
What other voltage is connected to the output. The output of the circuit cannot be outside of the power rails without some other power source pulling that point up.bphui said:
Can you post your schematic?
- #8
Averagesupernova
Science Advisor
Gold Member
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If the negative lead of the voltmeter is hooked to the negative supply when using a split supply setup I can see why you could get readings like this.
- #9
- #10
Svein
Science Advisor
- 2,316
- 813
Your schematic does not show which pins you use to connect to the power supply.
- #11
bphui
- 7
- 0
p
pin 7 connect to +5v
pin 4 connect to -5vSvein said:
pin 7 connect to +5v
- #12
Svein
Science Advisor
- 2,316
- 813
Using 100MΩ feedback with a 0.22μF input capacitor is a recipe for trouble. The time constant is 22 seconds - so it will take forever to stabilize.
- #13
Averagesupernova
Science Advisor
Gold Member
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I noticed this too. The whole things looks a bit odd. Wondering what is connected to the header?Svein said:
- #14
bphui
- 7
- 0
The header connects with pvdf film.Averagesupernova said:
- #15
bphui
- 7
- 0
Is 100M feedback with 0.22uF and 1000pF?Svein said:
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