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Why is the frequency and voltage of my Colpitts oscillator lower on breadboard than LTSpice?

I changed some components and I retain ultimately this behavior.
Antonio51's user avatar
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1 vote

RF coupler to measure output of PA

I assume this is the coupler that the OP is concerned about, image from his link On the one hand, it is usually good that all RF things that you connect to each other have the same, usually 50 Ω, ...
Neil_UK's user avatar
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1 vote

Why is a peak in the gain a sign of instability in a closed loop op-amp circuit?

I did a research and I noticed for having a stable circuit there should be at least 45 degree phase margin. There is a way that we can calculate phase margin form the gain-frequency plot as follows: ...
Andromeda's user avatar
8 votes
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Why is the frequency and voltage of my Colpitts oscillator lower on breadboard than LTSpice?

A breadboard will have capacitance between the connection rows. The jumper wires will have inductance. Real components will have parasitic resistance, inductance and capacitance that a simulation may ...
GodJihyo's user avatar
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Stages of audio amplification from mV to 20V+

it doesn't have to be in stages, but transistors suffer from being real devices do other things bedides amplifying (eg givving differen perfromance depending on the supply voltage or the temperature. ...
Jasen  Слава Україні's user avatar
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Stages of audio amplification from mV to 20V+

The days of home stereo sets have probably been over for a decade or two, but I suggest that you take inspiration from the blockwise structuring of those signal chains. An important interface was the &...
frr's user avatar
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Stages of audio amplification from mV to 20V+

It all depends on exactly what you want to accomplish. You can certainly design a Class A circuit that will amplify a signal of a volt or two up to 20 volts in a single stage, but it would tend to ...
GodJihyo's user avatar
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3 votes

Why is a peak in the gain a sign of instability in a closed loop op-amp circuit?

TLDR: Not always an indication of instability - a peak might be intended. However, an internally-compensated op amp is very often used to amplify linearly, where two resistors are chosen to set closed-...
glen_geek's user avatar
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9 votes
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Why is a peak in the gain a sign of instability in a closed loop op-amp circuit?

1.) A peak in the frequency response for a closed-loop gain is NOT an indication for instability. It rather indicates that the phase margin is smaller than app. 65 deg (for a 2nd order system). This ...
LvW's user avatar
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4 votes

Why is a peak in the gain a sign of instability in a closed loop op-amp circuit?

Is this statement always correct? I apologize for the brief answer, but the answer is no. A peak in gain (dB), it is not always a sign of instability in an Op-Amp circuit. A system is unstable if it'...
Math Keeps Me Busy's user avatar
2 votes

Stages of audio amplification from mV to 20V+

An audio amplifier generally has 3 stages, the input stage to buffer the weak signal to have weak voltage with low output impedance that can drive the next stage, usually a voltage amplification stage ...
Justme's user avatar
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2 votes

Stages of audio amplification from mV to 20V+

You're asking for a gain of 1000 overall. You will need to break that up into several stages. A brief proposal would be: Low-noise, AC coupled low-level preamp, gain of about 50 ~ 100, max swing ...
hacktastical's user avatar
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7 votes

Three-stage CE-CE-CC Amplifier

The problem with very low load values, such as a speaker at \$8\:\Omega\$, is that the driver stage needs to be able to both source and sink current, actively. Your output stage, a common collector or ...
periblepsis's user avatar
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1 vote

Three-stage CE-CE-CC Amplifier

I would check the second stage as this looks to have extremely high gain. Also consider the operating point of the base of the first two input stages. Try and calculate the DC voltage there, the DC ...
Tyassin's user avatar
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0 votes

Transimpedance amplifier with OPA838 - oscillation - supply voltage

You are using SOT23 package with 1.3mm pitch. The trace from output to C4R4 looks like 0.4 mm wide, and the length is about 6.5 mm. According to this calculator, So you effectively have a 33nH ...
Ale..chenski's user avatar
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3 votes
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How to share a single gain resistor among multiple op-amps in a circuit

My hacked solution: Source: https://www.youtube.com/watch?app=desktop&v=NoNgQpbj77Y&ab_channel=EngineeringProf Use one of these circuits, you should be able to parallel the current mirror. by ...
Voltage Spike's user avatar
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6 votes

How to share a single gain resistor among multiple op-amps in a circuit

The instrumentation amp single-resistor gain set works because both input amps are processing aspects of the same signal. You want to have currents from four different signals go through one resistor ...
AnalogKid's user avatar
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2 votes

Help me understand this high voltage amplifier circuit

I'm not in the mood for a complete analysis of this, but there are some things worth mentioning in more than comments. So, this will be sort of a partial answer. There are two glaring issues I take ...
Tim Williams's user avatar
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1 vote

Help me understand this high voltage amplifier circuit

I think the reason for Q5 is three-fold: to bring the DC voltage lower such that Q6 is properly biased and amplifies well. Amplifiy to keep the negative feedback operation. If you want Q6, you need ...
Designalog's user avatar
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2 votes

Help me understand this high voltage amplifier circuit

Q5. It allows the op-amp rails to be independent of the output stage rails. Q5 shifts the voltage down to whatever -VCC is. If you want to use 0 V for both your op-amp negative supply and the output ...
Neil_UK's user avatar
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0 votes

Single stage MOSFET Amplifier with terrible gain

One idea would be to put a large value cap across R_S. This way the DC bias circuit works correctly (the 220 ohm feedback resistor will set how much dc current is flowing) but that negative feedback ...
Jack Zylkin's user avatar
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How to improve gain for CC-CE-CC amplifier

When designing discrete transistor amplifiers, it is helpful if the oscilloscope is set to DC coupling so you can see where the DC bias are. The gain of the middle stage needs to take in to ...
qrk's user avatar
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0 votes
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How best to minimize shoot through with push-pull mosfet driver

If you want to turn on the MOSFET when the hall sensor triggers, you can do that: When the sensor triggers, it pulls down the output, which turns on the small signal P-MOSFET (X1) which turns on the ...
bobflux's user avatar
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0 votes

How to improve gain for CC-CE-CC amplifier

Several things: You have three stages, but only one has gain. You're trying to design it to get a particular amount of gain. It's likely that the gain drop you see when adding the third stage is ...
GodJihyo's user avatar
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0 votes

Comparator Using Common Gate CMOS

I'll be referring to these: simulate this circuit – Schematic created using CircuitLab Ideal diodes D1 and D2 limit the \$I_{REF}\$ current sources' compliance voltage to a maximum of +12V, so ...
Simon Fitch's user avatar
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1 vote

Comparator Using Common Gate CMOS

This is a large-signal effect, and in general, you'll often need large-signal effects to discuss comparators (which often turn stages fully on/off, slew them significantly, etc). Assume that M0 and M1 ...
nanofarad's user avatar
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0 votes

Noise decibel meter - how to convert MAX4466 voltage output to unweighted dB(SPL)

You can factor in the sensitivity of the mic at any point you desire. You know that the mic, when fed with some sound amplitude, either in Pa or dB(SPL), the mic outputs some voltage in V or dB(V), ...
Justme's user avatar
  • 148k
0 votes

DC current gain of transistor

The formula \$I_C = \beta I_B\$ is correct, but you are also correct when you say the the two currents \$I_B\$ and \$I_C\$ do combine, by Kirchhoff's Current Law (KCL) to form current \$I_E\$ that ...
Simon Fitch's user avatar
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1 vote

I have a AD9833 function generator which has the ability to change frequency from 1k to 1MHz but a fixed 0.6V output I want 1V to 10V pk to pk

You have an inverting amplifier in your design, with R16 = 3.9k . To get a gain above 1 you will need the feedback (optoresistor) value bigger than 3.9k. However, if you check the datasheet for NSL-...
Ale..chenski's user avatar
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1 vote

Why is the real component in my amplifier input impedance negative?

Test it with a resistor alone (e.g., disconnect Q2). Is it still negative? If so, you are now sure that it must be a resistive load, and there is no feedback or nonlinearity affecting the ...
Tim Williams's user avatar
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1 vote
Accepted

Options for line output doubling as headphone output

There is a type of chips called headphone amplifiers. Some of them work from single supply and can generate a negative supply for DC coupled output. They are available from multiple manufacturers.
Justme's user avatar
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1 vote

Why does the volume of the preamplifier change when a second audio signal is mixed?

You are short circuiting two outputs together. Or rather, mixing them with resistors. If they both have 100 ohm output impedance, the output from each device is halved because the output amplifier is ...
Justme's user avatar
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1 vote
Accepted

Why does the volume of the preamplifier change when a second audio signal is mixed?

To add two signals "properly", it is not enough to simply connect them with resistors. One should use an op-amp adder circuit. simulate this circuit – Schematic created using ...
Math Keeps Me Busy's user avatar
1 vote

Operation explanation of a low-swing differential receiver (amplifier)

Alexander Quilty's answer provides insight into the workings of this differential receiver. Here is a simulation. simulate this circuit – Schematic created using CircuitLab The output does ...
Math Keeps Me Busy's user avatar
0 votes

How to know that the output node of an amplifier is not well-defined?

It isnt well defined. There are two current sources both of high impedance fighting in series. Let say the above one has higher value then the node has net current being pushed into it so its ...
Hardik Jain's user avatar
0 votes

What is the output current of MAX4238ASA+?

The output is current limited so the usual max current rating is not available. Two graphs from page five (shown below) indicate how close to the rails that can be achieved based on output current. ...
RussellH's user avatar
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0 votes

What is the output current of MAX4238ASA+?

The output is characterized in terms of load resistance. See the section "Output Voltage Swing" in the "Electrical Characteristics" table. As long as the load represented by your ...
Dave Tweed's user avatar
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0 votes

LNA operating in saturation

What happens to an LNA noise figure when operated in Saturation Noise figure is defined as the ratio of the input signal-to-noise ratio to the output signal-to-noise ratio so, if the output moves ...
Andy aka's user avatar
  • 457k
3 votes

Operation explanation of a low-swing differential receiver (amplifier)

I believe this is because receivers for differential signals are NOT differential amplifiers. This is a common misconception. It is operating more like a Current Switch, or Crossing Detector. That is ...
Alexander Quilty's user avatar
1 vote

Why does this AM radio circuit not work?

For this kind of radio, you need a BIG antenna**, try for 100 feet of wire as high as you can get it, perpendicular to power lines if possible. Also, you need a good ground. Multiple earth ground ...
richard1941's user avatar

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