Peak Detector not working

[M.Rehan]

Simulation is working properly but real circuit causing problems





Output of this circuit is showing constant -4.8 V in real Circuit


Components used are same as in simulation

 

[SLK001]

Probably your diode is in backwards.

 

[betwixt]

You most definitely have something wired wrong - there is no way it can produce an output voltage greater than it's supply voltage.

The circuit isn't actually a peak detector, it's nearer to being a precision rectifier and buffer as there is nothing in it to hold the peak level. I presume you are measuring the output voltage with respect to ground and not the negative or positive rails.

Brian.

 

[M.Rehan]

@SLK
Diode is in right direction

@Brian
Its a -5V supply and shows -4.97V (schematic mistake)
I ll use capacitor parallel to resistor once get the right waveform

Input signal is with respect to ground and op-amp don't have any connection to ground

 

[crutschow]

Two possibilities:
Something is wired incorrectly.
The op amp or diode is bad.

 

[M.Rehan]

Same result for both diode and op amp changed

 

[skroz]

Probably you left input pin 3 floating.

 

[M.Rehan]

Attached images shows how input signal is fed.

 

[crutschow]

Then there must be an error in your wiring.
Is the power supply common connected to your input common?

 

[SLK001]

The virtual ground of your ICs is at +1.2V. If your input is 1V peak and symetrical around 0V, then at no time will the diode be in play. Your signal is negative with respect to the opamp and always will be.

 

[M.Rehan]

Circuit didn't work so changed to other one
Thanks

 

[c_mitra]

Circuit didn't work so changed to other one

But did you understand why it did not work? Perhaps you can do a simulation in spice and try to figure out...

 

[FvM]

The virtual ground of your ICs is at +1.2V.

Where? How? There's no "virtual ground" in the circuit.

I guess you are referring to the mid supply level. It's irrelevant in this circuit as long as the common mode range of the OPs isn't violated.

 

[SLK001]

Where? How? There's no "virtual ground" in the circuit.

I guess you are referring to the mid supply level. It's irrelevant in this circuit as long as the common mode range of the OPs isn't violated.

Look at #8. His input signal is ground based (I'm assuming that it is symetric around ground). His opamp's "mid supply level" is above the maximum signal from his "ground based" sine wave generator. And his input circuit is DC coupled.

 

[vitoa]

Hi, instead of using ampop why you dont use AD8307 ( multistage logarithmic instrumentation amplifier ) ? You get analog out on any signal from DC to 500MHz
Here are some measures:
Power in | Vout
-20dBm 1,678V
-10dBm 1,9237V
-5 dBm 2,057V
-1dBm 2,1502
0 dBm 2,1808V



There are many circuits using AD8307 googalize it. Very low cost easy implementation.

Happy peak detection.

 

[betwixt]

Look at #8. His input signal is ground based (I'm assuming that it is symetric around ground). His opamp's "mid supply level" is above the maximum signal from his "ground based" sine wave generator. And his input circuit is DC coupled.

I'm not sure why "mid supply level" makes any difference in that design. The input voltage (ground) is well within the limits for that device so the problem shouldn't be input overload.

Brian.