# Questions tagged [ideal]

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44 questions
3answers
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### Ideal Battery in Circuit

Does Kirchoff's voltage law hold when we connect a single battery to a circuit that has no other components. If it does hold, kindly let me know how. If it doesn't, how do we reconcile with that?
1answer
28 views

### Current readings of Ammeter

I was trying to solve this problem (number 27) and as per the KCL equations I am getting that an infinite number of Ammeter readings are possible. I used KCL after taking the outer loop as the ...
3answers
73 views

### Confusion with impedance matching example using an ideal transformer

Starting from "The Effective Resistance of a Load Resistance attached to a Transformer" at page 8 of this document there is an example where it demonstrates impedance matching using an ideal ...
1answer
78 views

### Ideal Op Amp Circuit

I have a question about the circuit below. I want to find Vo in terms of Vi. But I don't fully understand the principles about an ideal op amp's output. You will see my questions in bold at the bottom ...
2answers
77 views

### How is voltage divided between two reverse-biased ideal diodes?

Suppose we have two identical ideal diodes (without any resistance or voltage drop). We connect these two diodes in series, in the same direction, and reverse-bias them with voltage V. Now we have two ...
0answers
34 views

### A basic question about an ideal and a non-ideal transformer

An ideal 1:1 transformer rejects common-mode voltages and non-ideal transformer passes it partially to the secondary through due to its winding capacitance. What can be said about the differential-...
1answer
47 views

### Average Power of load conected to an Ideal Transformer

Where does the 1/2 come from in the power equation?
1answer
49 views

### Finding indication of ideal ammeter

Would anyone share some tips, advices for solving this task? So far, I have dealt with far simplier electric circuit's tasks. This is new to me. Any kind of help or advices are appreciated, thanks!
2answers
82 views

### Combining perfect voltage and current sources

I am attempting to reduce the circuit shown into a form of a single voltage source and resistance in series using Thevenin and Norton conversions. I approached the problem by first considering a ...
1answer
74 views

### Ideal Transformer Theory Question

I have some questions regarding ideal transformers, similar to the one seen below: When talking about 'ideal transformers', can I calculate the current on the primary side by finding the complex ...
1answer
55 views

### Ideal switch acting on a capacitor

Let's consider this circuit: and suppose that the capacitor C1, charged at the input voltage Vin, at time t=0 is connected by the switch to the virtual ground. Assume also that C and C0 are initially ...
1answer
311 views

### Schmitt trigger with 741 op-amp not behaving as in simulation

I am implementing a Schmitt trigger using the circuit shown below. This circuit consists of one LM741 op-amp, which acts as an asymmetrical Schmitt trigger with a single power supply. According to ...
2answers
84 views

### Maximize output signal swing in digital circuit design

Please help me understand the following paragraph in chapter CMOS Digital Logic Circuit from book"Sedra/Smith micro electronics circuit 6e". An ideal VTC is one that maximizes the OUTPUT signal ...
3answers
92 views

### At what resistance can a real inductor act like an ideal inductor?

So it's my understanding that an ideal inductor with a constant voltage applied should have a constant ramp for the current through it (a triangle wave), but an inductor that's not ideal (with ...
1answer
450 views

### Symbol for ideal voltage source vs symbol for real voltage source

Wikipedia's article on Voltage source shows the figure below. It says in the figure that the following symbols is an ideal voltage source. However, elsewhere in the same article they have a circuit ...
1answer
47 views

### How to represent the variation of electrical resistance with frequency for ideal circuit elements?

Can anyone please help me a little and guide me through representing the variation of electrical resistance with frequency for an ideal resistor, coil and capacitor. I will do all the work I can ...
2answers
84 views

### Transfer function of Operational Amplifier

I am trying to solve the following operational amplifier circuit to get its transfer function. I have tried two different approaches, one is elementary approach by finding V- and V+ and equating ...
1answer
32 views

### Question with using Isc -> Any errors?

For the picture below, the answer for Voc is 7.5V, but when I add an Isc at terminals AB, and use KCL, I get Voc = 3.75V. Here are my steps/equations: (1) 15 = 4I1 - 2Isc (2) 0 = 3Isc - 2I1 I get ...
1answer
4k views

### What is a typical diode's ideality factor?

Some background, for anyone unfamiliar: The Shockley diode equation is $I_D=I_S·(e^{\frac{V_D}{n·V_T}}-1)$ with the quantity $n$ called the ideality factor, a number between 1 and 2. Ideal ...
1answer
377 views

### Why is the Exciting Current zero in an ideal transformer?

An ideal transformer having infinite permeability core is supposed to have zero exciting current. An ideal transformer has infinite permeability core, which means that all the flux in the universe ...
1answer
453 views

### Output Impedance of a Wilson Current Mirror

Is the ideal output impedance of a Wilson Current Mirror 0? Also, in the formula for the actual output impedance of Wilson Current Formula (i.e. R_out = [B/2]* r_o), what does r_o stand for? Also, ...
1answer
159 views

### Step Response of Ideal Inductor with Current Source

I'm taking an electronics course to get a physics minor (I'm an applied math major) and today, the professor shows a diagram of an ideal current source connected to an ideal inductor. Crazy stuff I ...
2answers
144 views

### Op Amp Summing Point Problem (Ideal)

I have a quick question on this example problem on (ideal) OpAmp analysis. I understand the basic cases of negative and positive feedback, and how there is a virtual short between the input pins of ...
2answers
71 views

### Analysing an op-amp circuit and I do not understand a specific resistor value

Hi was reading this article and I read: There is written: Here, the feedback resistor Rf provides a discharge path for capacitor Cf, while the series resistor at the non-inverting input Rn, when of ...
3answers
117 views

### Gain not containg the output, non ideal, resistor

I was working a mathematical model of a non ideal op-amp circuit and I saw a slide in the following presentation: The question I have is the following: Why does the close-loop gain \\$\frac{\text{V}_\...
2answers
101 views

### Ideal Voltage/Current Source Circuit Analysis

I am trying to understand what it going on in this circuit diagram and how to go about solving this problem. I am told to find Vx given that the current in the central wire is zero. Does this mean ...
1answer
564 views

### Ideal diode - PNP emitter-base breakdown voltage question (PMOSFET)

I'm hoping to create this ideal diode. With 12V. However, I feel like this would require the two PNP transistors to have an emitter-base breakdown voltage of 12V or more. Is this correct? (Such PNP ...
2answers
203 views

### Can I buy an ideal diode? How do I OR two power supplies together

I'm trying to switch over from USB power to external power if it's present. (External power is 6V to 13V). The current is 2A. To do this I'm using diodes 1 and 3. See image below. ("OR" configuration....
3answers
428 views

### Ideal diode circuit techniques

The circuit above has 4 IDEAL diodes and there are 16 cases to check. Is there any shortcut to fiqure out which case to check first (to guess which diodes are on or off)?
1answer
347 views

### Ideal Transformer equations when the secondary winding is short-circuit?

This is my problem Now I know that ideally $$V_1/V_2 = 1:α$$ and $$(J_1-J_3) = α (J_2-J_3)$$ where J1 is the current of the left mesh, J2 is the current of the right mesh and J3 is the current of ...
2answers
512 views

### Charging an ideal capacitor through an ideal diode, forever

Some context for why I am asking the question: I have application in which I am to charge a supercapacitor from a voltage source which is equal to the the cap's rated voltage. As such I considered ...
2answers
429 views

### Reverse current blocking on switching regulator

I was thinking what is the best solution to add a reverse current blocking on switching regulator. My first thought was to look for an ideal diode circuit but all of them were too much expensive. The ...
1answer
82 views

### Am I interpreting this basic diode question correctly?

I am doing a question related to diodes from Sedra Smith Micro electronics and here is the question snip: In the second part of the question where it says that if 1mV is being drawn by a load ...
1answer
238 views

### ideal diode circuit question

Can some one show me an example about how to do these 2 simple questions.. (a.)As Vo=0.7V, want [Is] (b.)As Vo=1.5V, want [R2]
2answers
554 views

### Does a voltage source/diode in a circuit act as an open or a short circuit?

This question originates from a diode question in which we modelled diodes using the simple piece-wise linear model. According to the lecture notes, the diode acts as a battery after attaining Vf(...
1answer
291 views

### Help with ideal diode model question?

I've been asked to use the ideal diode model on the circuit below to determine the values of I and V. To determine which diodes were on or off, I considered each possible case: D1 and D2 are both ...
1answer
170 views

### What happens if power sources are connected in violation of ideal circuit theory?

My circuits knowledge is (mostly) limited to ideal circuit theory, where: An ideal voltage source maintains a prescribed voltage regardless of current flowing though its terminals An ideal current ...
1answer
322 views

### Does an Ideal voltage source with current flow from negative terminal absorb power?

I had a question during a physics tutorial today and it has left me quite confused. One of the questions was to find the power delivered by the 6V source. I figured that P=VI, I is negative with ...
1answer
9k views

### Difference between an ideal integrator and a practical one

I only learned about the ideal integrator design (top circuit), but when I searched for a practical model for an integrator I found it was like the one in the bottom circuit. Two new elements, Rf and ...
1answer
313 views

### bjt current biased in ltspice

For some reason when current biasing a very simple BJT common emitter circuit in ltspice, the current source needs to produce a massive amount of voltage. Why would this be? I'm biasing it at a Q ...
1answer
352 views

### Replacing Ideal current source in two-stage opamp

I am now investigating on replacing the ideal current source with the circuit similar to the one attached below. Why would the mosfet M16 be connected to drain of M12 ? I am confused about how the ...
1answer
488 views

### Ideal wireless channel (coherence time/bandwidth)

Wireless channels can be characterized as either slow or fast fading based on their coherence time and signal length. Similarly, they are either flat fading or frequency selective depending on their ...
1answer
845 views

### ideality factor diode > 2 possible?

Using non-linear regression I have worked out the ideality factor to be greater than 2 (2.04987187490894) using spreadsheet software. Is this realistic for a diode. Is the maximum ideality factor ...
3answers
6k views

### What causes the voltage drop in a realistic voltage source when the load current increases?

The realistic(practical) voltage source is modeled as an ideal voltage source plus a series resistor R in the above figure. In an ideal voltage source whatever the current load is the voltage would ...