# Tag Info

### Reason to increase output impedance in an non inverting op-amp

This type of scheme is to decrease the amount of capacitance that the opamp "see's" on it's output, if you were to decrease the series resistance beyond a certain point on the output its ...

### What's the gain of this circuit?

Some calculations must be done and the potentiometer must be taken into account:

### What's the gain of this circuit?

Lets consider the Op-Amp as an ideal OP-AMP. So the output of the OP-Amp can be seen as an ideal voltage source (depending on V+ and V-). If you look at the potentiometer, it has no influence onto V+ ...

### What's the gain of this circuit?

A classic, first order, non-inverting amplifier as shown will typically have a closed loop gain of 1+ R2/R1 = 1 + 75/1 = 76. The 10K potentio-meter looks like a 10K load to the amplifier and will only ...
Accepted

### Can an output voltage of a simple comparator be higher than the input voltage?

You don't show the opamp supply, but when used as a comparator with no negative feedback, the op-amp output will go from one extreme (the negative supply or ground if single supply) to the other (the ...
Accepted

### Op-amp - Lead compensator design

You need to design your active filter - the compensator - so that it exhibits a gain of 20.6 dB at 5 kHz. Calculate the magnitude of the filter with the selected pole-zero pair. This pair is ...
1 vote

### How do you turn on an LED when the input voltage is less than 12V?

This design will switch on one or more LEDs with a reasonably constant current of 10mA, as soon as the supply voltage exceeds the LEDs' combined forward voltage. That would be 1.6V for a single red ...
1 vote

### Trying to simulate a basic op-amp intrgrator but cannot seem to find any error in my circuit

You have built a 200 Hz low-pass filter with gain of 10x are feeding it with 45 Hz. So with those values, you will not see any ramps as the ramp is very quick compared to the frequency of the signal. ...

### Trying to simulate a basic op-amp intrgrator but cannot seem to find any error in my circuit

The integrator is too fast. +12V at the input will produce this input current: $$I_{IN} = \frac{V_{IN}}{R_1} = \frac{12V}{820\Omega} = 14.6mA$$ Ignoring R2, all this current passes through C1, ...

### Trying to simulate a basic op-amp intrgrator but cannot seem to find any error in my circuit

Ignoring R2, a 12V input means almost 15mA, so a dv/dt at the output of almost 150V/ms until it saturates. At 20ms/div it will change 10V in about 1/200 of a division. So the ramps are there, just not ...
1 vote

### How do the input current bias and the driven ground circuits in OpenBCI Ganglion work?

The driven ground part is simply an AC ground voltage driver which outputs 1/2 of the supply voltage which is used as the "ground" for AC signals. This is the baseline level around which ac ...
Accepted

### Transfer function for CMOS opamp design

Your general analysis looks correct. The design and analysis of a two stage op-amp is a well-known and well-treaded problem. questions: Is this the correct approach I used? It looks correct. You can ...
Accepted

### Find resistors for an inverting op amp band pass filter

The input pair of components create a high pass filter, the feedback pair of components create a low-pass filter. Using f(-3dB)=1/(2 * pi * R * C) for each pair of components (input pair and feedback ...

### Multiple Resistors for Rf in Op-Amp

Yes, if you are using the feedback equations you can consider the resistors in series to be the same resistance.

### How to find the tolerance on the output of an op amp circuit?

Sensitivity study for parametric variations. (Idea from the text "Linear and nonlinear circuits" by - Leon O. Chua, Charles Desoer, Ernest T. S. Kuh - McGraw-Hill:

### I don't understand this temperature controller circuit's behaviour

This is a fundamental issue. You need to prevent the output from going so close to ground that the difference between the inputs becomes less than the offset voltage of the op-amp, if it's driving the ...

### How to find the tolerance on the output of an op amp circuit?

I always start by including the error terms in the schematic. I believe that it looks like this. Then people can follow your equations easier. Unless you are using an exotic opamp, or your closed loop ...
1 vote

### Convert analog piezo "transition" to digital signal

The thread here, shows that a piezo can activate an LED. If you use a high efficiency AC coupled opto isolator with digital output like this one from Toshiba and drive the LED with the piezo sensor ...

### Voltage Buffer Vs Impedance matching

A couple of things Using TL072 as a voltage buffer doesn't offer any benefits if the preceding stage also is TL072. Load driving capacity stays the same. You do not need impedance matching to avoid ...

### Voltage Buffer Vs Impedance matching

Yes, there is impedance mismatch. What you don't realize that it is what you want. Ideal op-amps have zero output impedance and infinite input impedance. Those are good things. Imagine if you did ...

### Measuring accurate voltage across a shunt resistor for high frequency AC current sensing

You didn’t state your accuracy requirements. A current transformer may be an option which handles isolation and amplification (to an extent)but won’t be super accurate. Single ended measurement is ok ...
1 vote

### Calculate Gain of TS922

My question from comments: Do you know the standard op-amp configurations? Your reply from comments: no.... Since you are new to electronics, operational anplifiers (Op-amps) must be on your list ...

### Measuring accurate voltage across a shunt resistor for high frequency AC current sensing

It all depends on your transformer. Note that the opamp tolerable voltage range and voltage supplies must be larger than the largest voltage swing you expect at the output. This circuit is configured ...

### Calculate Gain of TS922

This amplifier IC contains two opamps.Opamp2 is configured as a unity gain follower. For OPAMP:2 The output of the voltage divider is connected to non inverting input of opamp. The voltage at the OUT2 ...

### Simple inverting op amp not working

The signal generated by the mic and 2.2k bias resistor will have a DC offset that you decouple with the 1uF capacitor. Because of this decoupling, you have an (ideally) pure AC signal, meaning the ...
1 vote
Accepted

### Simple inverting op amp not working

Where is the voltage supposed to come from that ever could get the "-" input below the "+" input? You either need a -9V supply for the opamp, or you need to put its "+" ...

### Why is the output of this LM324 op-amp circuit 0V? Orcad/pspice question

In your circuit, the triangle wave amplitude will vary inversely with frequency; as you vary the freq of the squarewave oscillator, the integrator has more or less time to ramp, changing the resulting ...
1 vote
Accepted

### Non inverting opamp with bias DC

You did nothing wrong. Just choose the value of your resistors R3 and R4 (My R9 and R10). Like this ...

### LM358 Output Voltage Issue / Compensation

The circuit is way too complicated for what you're trying to do. A slight refactoring eliminates the rail-to-rail problem altogether. First of all, a single opamp can do the conversion you're looking ...

### Is using a buffer before a non-inverting input redundant?

This is redundant, but there may be valid reasons to do so. For example, best practice is to not leave unused op amps unwired, as if they start oscillating in open loop, that noise on the board might ...
1 vote

### Is using a buffer before a non-inverting input redundant?

Given that the input doesn't have to withstand any overvoltage conditions with its 0..100mV voltage range, this is just a simple way to make use of an unused OpAmp section in a dual OpAmp IC (as you ...
Accepted

### Why is the output of this LM324 op-amp circuit 0V? Orcad/pspice question

Seems that power supplies are not "wired" (no dots ?). Your timebase is too short. It should be at least of 300 ms. With my simulator, it start promptly. (2 ways). Here is the simulation ...

### Why is the output of this LM324 op-amp circuit 0V? Orcad/pspice question

It is likely stuck in a quasi-stable state. It may eventually start oscillating if your simulation runs long enough. Rather than that, try replacing one or both power supplies with sources that switch ...

### How to make an LED light when motor stops running?

Swapping the inputs to the op amp (or comparator) ringed in red will achieve what you want. OR Change the LED driving transistor to a PNP, emitter to +5, collector to ground via LED (with appropriate ...
Accepted

### How to design an I/V Converter for Arduino

For a simple setup, i would use this approach: NOTE: I don't fully understand why you want a 0-4.5V signal range? simulate this circuit – Schematic created using CircuitLab NOTE: This circuit ...