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10 votes
Accepted

Hysteresis on inverting terminal for comparator circuits?

Here are the two scenarios you describe, one with negative feedback (left), the other with positive (right): simulate this circuit – Schematic created using CircuitLab The only difference ...
Simon Fitch's user avatar
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9 votes

Hysteresis on inverting terminal for comparator circuits?

The point of hysteresis is to reinforce the output state using the input, so that if the input signal has a small amount of noise on it, your output does not change state due to that noise. The ...
mapplejacks's user avatar
7 votes
Accepted

BJT four-resistor bias circuit analysis, parallel resistors

Thevenin's theorem applies as follows:
Franc's user avatar
  • 1,515
6 votes

Hysteresis on inverting terminal for comparator circuits?

Vref does change, but into wrong direction, so it amplifies noise instead of ignoring noise. So when input voltage is between thresholds, the output oscillates.
Justme's user avatar
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6 votes

Hysteresis on inverting terminal for comparator circuits?

You can invert the output with a digital inverter and thus apply positive feedback to the inverting input. Otherwise you've got negative feedback, which makes an amplifier or an oscillator, depending ...
Spehro Pefhany's user avatar
6 votes

BJT four-resistor bias circuit analysis, parallel resistors

Let me provide a different way of looking at it. It may be simpler to see your question with regard to \$R_1\$ and \$R_2\$ using math. Let's keep the BJT base current in place and assume that it is ...
periblepsis's user avatar
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4 votes

Is it wrong to use Thévenin's theorem on this memory circuit?

The upper NOT gate has a Thevenin equivalent circuit for the particular state it is describing. In that state it is shown as a voltage source with +V2, and +V1 and a series resistance each. It is ...
citizen's user avatar
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4 votes

Failing to compute Thévenin voltage

What is wrong about my reasoning? How is the reasoning of the solution explained? You need to resolve current i.e. you need to establish what \$I\$ is. \$I\$ equals the supply voltage (\$V_1\$) ...
Andy aka's user avatar
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4 votes

How to solve Thevenin and Norton circuit?

From what I remember, you need to short the circuit for voltage sources then open circuit for current sources. With that, I used it to solve for RTH which is 58 ohms (but i don't know if I got it ...
Andy aka's user avatar
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3 votes
Accepted

Node equations for Thevenin voltage

Nodes Let's get one thing straight. When doing circuit analysis: simulate this circuit – Schematic created using CircuitLab Spend some time to make sure you are comfortable with all three: Top:...
periblepsis's user avatar
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3 votes
Accepted

Thévenin's Theorem - What to do when ending up with a voltage source in paralell with one resistor?

You made two errors. You need to calculate the thevenin voltage by finding the open-circuit (no load) output voltage of the circuit. You do this using the full schematic of the circuit, not one with ...
The Photon's user avatar
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3 votes
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Finding the Thévenin and Norton equivalents for a circuit

I would really appreciate some help Usually, these problems area easier to solve by converting the voltage to a current source: - Then, because current sources play no role in the impedance it's ...
Andy aka's user avatar
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3 votes

Thevenin's Equivalent using KCL - Circuit Analysis

I will show how I would find the impedance between A and B, 1) if I have a simulator handy, and 2) by hand. simulate this circuit – Schematic created using CircuitLab If I have a simulator ...
Math Keeps Me Busy's user avatar
3 votes

Thevenin's Equivalent using KCL - Circuit Analysis

I'm going to address the title of your question and, as you say, assume that this is a practice question for circuit analysis. Thevenin's Equivalent using KCL - Circuit Analysis I gather that \$R_{_\...
periblepsis's user avatar
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3 votes

Currents in short circuit wires connected in parallel

15 V and 1 kΩ define a total current of 15 mA. That's all you can say given the information in that ideal schematic, I1 + I2 = 15 mA. If you had more information, like the residual resistance of the ...
Neil_UK's user avatar
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3 votes

How can I find Thévenin equivalent circuit of the NFB op-amp input?

That's a nasty question. The trick is to realise that node E is a virtual Earth, always 0V, maintained by the right-hand op-amp itself. Assuming that op-amp is ideal, the Thevenin equivalent between E ...
Simon Fitch's user avatar
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3 votes

How can I find Thévenin equivalent circuit of the NFB op-amp input?

Beyond formal explanations The answer is obvious: Looking at the op-amp input in a circuit with negative feedback you see zero resistance. It will probably do you a good job. But in addition, we have ...
Circuit fantasist's user avatar
3 votes

How to find current for Thevenin equivalent circuit

Just turn the voltage source (Vin) and R1 into a current source: - Hence, the Thevenin resistance (as viewed from terminals C and D is R1 || R2. It's called source transformation and is an important ...
Andy aka's user avatar
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2 votes

Thevenin's Equivalent using KCL - Circuit Analysis

First, I will present a method that uses Mathematica to solve this problem. I know that this approach is not 'smart' but this method will work all the time, even when the circuit is (way) more ...
Jan Eerland's user avatar
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2 votes
Accepted

Thevenin equivalent- what did my professor do

Looking at his solution, whenever I made a move to combine resistors he did something that changed the source voltage too. This doesn't make sense to me because it is a source. I can understand your ...
periblepsis's user avatar
  • 11.2k
2 votes

Thevenin/voltage logic

The relevant concept here is that an ideal voltage source will maintain the same voltage across its terminals no matter how much current is drawn from them. So you can add as many resistors as you ...
vir's user avatar
  • 20.3k
2 votes

Is it wrong to use Thévenin's theorem on this memory circuit?

Logic gates and in general all logical devices are non-linear devices, so you cannot apply Thevenin.
Franc's user avatar
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2 votes
Accepted

DC Thevenin voltage

Hint I am having difficulty recreating the electrical circuit and I do not know the steps to find Vth The method I use is called circuit reduction. Can you see what I have done here (I've made a ...
Andy aka's user avatar
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2 votes
Accepted

Thevenin/voltage logic

I'm trying to find the Thévenin voltage of this circuit Just reduce the circuit in steps to focus on what you need to solve it: - So, the Thévenin voltage will be \$\dfrac{v_s}{2}\cdot 2R||4R = \...
Andy aka's user avatar
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2 votes
Accepted

How can there be no Thévenin voltage with only a dependent voltage source?

The circuit is composed only of linear components - impedances and a linear dependent voltage source. Hence the overall circuit is linear. From the linearity of the circuit, it follows that the ...
nanofarad's user avatar
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2 votes

Min and max resistance of this network with potentiometer

As you suggested in the comments, the potentiometer is just two resistors in series, which I will call \$R_1\$ and \$R_2\$ here: simulate this circuit – Schematic created using CircuitLab Total ...
Simon Fitch's user avatar
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2 votes

How to solve Thevenin and Norton circuit?

In your example, you know you got \$-35\:\text{V}\$ and, when a \$10\:\text{V}\$ source was connected you then got \$1.125\:\text{A}\$. So the Thevenin resistance is \$\frac{10\:\text{V}-\left(-35\:\...
periblepsis's user avatar
  • 11.2k
2 votes

BJT four-resistor bias circuit analysis, parallel resistors

The answer to your question depends on the node which is used to "look" into the circuit. 1.) When you look into the circuit from the upper node (Vcc) you see a resistor which equals a ...
LvW's user avatar
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2 votes

How to find current for Thevenin equivalent circuit

The problem is that I don't know how to calculate the current flowing into the output when generators are short circuited. The result should be I = V_in/R1, but the current after R1 will split in the ...
The Photon's user avatar
  • 131k
2 votes
Accepted

How to find current for Thevenin equivalent circuit

I understand that V_th is obtained by opening the terminals of the output, so that V_out = V_in R2/(R1+R2). The problem is that I don't know how to calculate the current flowing into the output when ...
periblepsis's user avatar
  • 11.2k

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