Skip to main content
17 votes
Accepted

I think I found an error in an electronics book. Are my equations correct here?

Standard Form Over some time, standard forms have been developed for these equations. There's a reason why. But I'll get to that in a moment. The usual 1st order low-pass standard forms for your case ...
jonk's user avatar
  • 78.2k
13 votes

How does this trick to finding the Thevenin Resistance work?

You're not really short-circuiting the voltage sources - the voltage sources are already presenting a zero impedance to the circuit. You're just setting them to zero voltage so that the output voltage ...
Neil_UK's user avatar
  • 168k
12 votes
Accepted

Thevenin Equivalent Voltage: why ignore the 3-kΩ resistor?

Computing a Thevenin Equivalent requires two steps: Obtain the Thevenin Impedance \$Z_{TH}\$ Obtain the Thevenin Voltage \$V_{TH}\$ In order to compute \$Z_{TH}\$ you have to "turn off" the ...
Collado's user avatar
  • 236
11 votes
Accepted

Contradiction:Maximum Power Transfer and High resistance of load

You are in good company. The maximum power transfer concept frequently causes confusion. Take note of the fact that maximum power transfer does not mean maximum power efficiency. I think this may be ...
user57037's user avatar
  • 29.4k
11 votes
Accepted

How does this trick to finding the Thevenin Resistance work?

This is a classic example of superposition as applied to linear systems - if you consider your circuit as a function mapping excitations (the voltages and currents of independent voltage and current ...
nanofarad's user avatar
  • 20.1k
10 votes

Thevenin Equivalent Voltage: why ignore the 3-kΩ resistor?

The Thévenin voltage is also known as the "open-circuit" voltage. In this case, the open circuit is between points A and B. Because it's an open circuit, no current flows through the 3k resistor, and ...
Shamtam's user avatar
  • 3,636
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
  • 36.5k
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
8 votes

Thevenin Equivalent Voltage: why ignore the 3-kΩ resistor?

The Thevenin voltage is when the output terminals are open-circuit so any series resistance (3K in this case) has no effect. We can also ignore the 4K resistor since it's in series with a current ...
Spehro Pefhany's user avatar
8 votes

I think I found an error in an electronics book. Are my equations correct here?

The book is wrong. You are right. You can verify by punching in random sets of sets of values into the left-hand side and right-hand side. They are off by a factor of 1/R. It doesn't even need to be ...
DKNguyen's user avatar
  • 56.8k
8 votes

Calculating resistor's current and voltage using Thevenin's theorem

First thing I want to say to you: electronics is only one of my hobbies. I'm not an EE and I've only a high school education. If anything, my own life is all about CS, too. That, and solving certain ...
jonk's user avatar
  • 78.2k
8 votes

How does this trick to finding the Thevenin Resistance work?

Consider this: - Would you say that the Thevenin resistance looking into the A and B terminals is any different if the voltage source was 36 volts or 1,000,000 volts? Would you say that the Thevenin ...
Andy aka's user avatar
  • 460k
8 votes
Accepted

How to analyze this RC circuit without finding Thévenin's equivalent circuit?

KCL Here's your re-drawn schematic (I'm in the practice of re-drawing schematics as a rule): simulate this circuit – Schematic created using CircuitLab My KCL sets up like this (treating your ...
jonk's user avatar
  • 78.2k
7 votes
Accepted

Resistor in parallel with a short circuit. Will current flow through it?

If the short circuit is perfect, the two leads of the resistor are at the same Voltage potential. In that case, no current can possibly flow through the resistor, no matter how much current you run ...
frr's user avatar
  • 2,818
7 votes
Accepted

BJT four-resistor bias circuit analysis, parallel resistors

Thevenin's theorem applies as follows:
Franc's user avatar
  • 1,444
6 votes

How do we derive the values for these Thévenin equivalent circuits?

The circuits are completely different, one has voltage source and the other has current source. As explained in the text you quoted, voltage supplies have zero impedance, and current supplies have ...
Justme's user avatar
  • 152k
6 votes

Determine Thevenin's equivalent circuit

Step by step. Don't need text but rules say 30 char.
stretch's user avatar
  • 467
6 votes

How to analyze this RC circuit without finding Thévenin's equivalent circuit?

Well, using Laplace transform we can write: $$\text{R}_\text{in}\left(\text{s}\right)=\text{R}_1+\left(\text{R}_2\space\text{||}\space\left(\text{R}_3+\frac{1}{\text{sC}}\right)\right)\tag1$$ Where \$\...
Jan Eerland's user avatar
  • 7,854
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
  • 152k
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
  • 9,908
5 votes
Accepted

Misunderstanding of output impedance and linearity

You have to separate some things first. Thevenin by itself has nothing to do with output impedance. Thevenin is just a method for "shuffeling around" sources and impedances (resistors) and represent ...
Bimpelrekkie's user avatar
5 votes
Accepted

Thevenin equivalent with non-constant voltage

If you put it as an answer I'll accept it Thevenin's Theorem applies to AC and DC circuits. Oh go on then I'll add some more stuff from hyperphysics: -
Andy aka's user avatar
  • 460k
5 votes
Accepted

Thevenin equivalent or mesh-current in a diode circuit

The Thevenin voltage isn't \$3\:\text{V}\$, though it's not terribly far from it. There are a variety of ways to compute it but none of them look like what you did. One way to think about solving for ...
jonk's user avatar
  • 78.2k
5 votes

Determine Thevenin's equivalent circuit

Can anyone tell me what the right answer is/ where I have gone wrong. Here's where your error is: -
Andy aka's user avatar
  • 460k
5 votes

Why are resistors that are shorted and connected to each other considered to be in parallel and not in series?

Because these are the same circuit: simulate this circuit – Schematic created using CircuitLab
Quitting Due To Antisemitism's user avatar
4 votes

Calculate using Thevenin's theorem

Warren Hill is telling you exactly what the Thevenin Theorem says: The Thevenin voltage is what you'd see across the terminals if you removed \$R_6\$ and the Thevenin resistance is the Thevenin ...
jonk's user avatar
  • 78.2k
4 votes
Accepted

Thevenin's theorem in transistor circuit

Perhaps all you need is some visual aid. Here's your circuit and its equivalent version once I cut the top 22V rail in the middle. (You have to ask yourself why I can cut the circuit between those ...
Sredni Vashtar's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible