What is Current source: Definition and 136 Discussions
A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it.
A current source is the dual of a voltage source. The term current sink is sometimes used for sources fed from a negative voltage supply. Figure 1 shows the schematic symbol for an ideal current source driving a resistive load. There are two types. An independent current source (or sink) delivers a constant current. A dependent current source delivers a current which is proportional to some other voltage or current in the circuit.
Figure:
My attempt at a solution:
1st kirchoff law:
$$J=2I_0+I_0=6\, \textrm{A}$$
$$V_1+8=10\rightarrow \boxed{V_1=2}$$
$$V_1=6V_S\rightarrow \boxed{V_S=4\, \textrm{V}}$$
We are looking for ##P## generated in ##J##
$$V_J=V_12\cdot J=22\cdot 6=10\, \textrm{V}$$...
So basically we can have a constant current but i don't understand this circuit.
for example: i can have the Ia what ever I want with current divider rule: Ia = Iq * R2/R3. So Ia is proportional to the ratio of R2/R3.
And if i give a resistor at the collector terminal, if i change it between...
As per ohms law the current is generated based on voltage and resistance V=IR. So if 5v and 1k resistor the current 5mA flows in resistor. But if I take a current source, can I pump any amount of current to resistor? So, current drawn is not characteristic of resistor?
Dear PF,
I am trying to solve practice problem 8.2. I am stuggling with part B of the question which asks us to find diL(0+)/dt, dvC(0+)/dt and dvR(0+)/dt.
My attempt can be seen below. Before t=0 the 4A current source is not present and thus it is an open circuit. A capacitor acts as an open...
Summary:: I was trying to derive the equation for the output impedance of the ICIS circuit.
Here's what I've tried so far.
What I have derived does not agree with the one provided in my book.
Since it is a current source the negative feedback must increase the output impedance. The one I...
Summary: Facing a circuit with 2 parallel resistors and 2 current sources (1 dependent, 1 independent). Trying to find the current, voltage, power delivered by the independent current source and power delivered by the dependent current source.
I'm trying to start by finding the current i0 but...
I am so sorry if I am posting this in the wrong forum; it is just not a homework problem, and I can't find the right place  it's more of a study help question.
Homework Statement
Homework Equations

The Attempt at a Solution
Here's my work :
When I add the DC current source , it shows a red dotted line and won't connect to other elements .
Any help would be greatly appreciated !
Alright. So I'm getting two different solutions depending on how I look at this problem, and I know one is correct but I don't know why the other would be incorrect. So, given this general circuit of a constant current source driving an RC circuit in parallel:
Now, what they tell me in class...
Homework Statement
The diagram of the electric circuit, the problem statement (and an attempt) are included in the file below.:
https://www.docdroid.net/RD0ZEgA/question3.pdf
Homework Equations
Dependent Current Source
Nodal analysis
Short Circuit Current
Thevenin Voltage
Thevenin...
i was reading about CSI and the first paragaph said "A constant current source is assumed here, which may be realized by using an inductance of suitable value, which must be high, in series with the current limited dc voltage source. " and it says nothing else about it , so clearly it's a basic...
Hi,
I am building a charger for my bicycle front and tail light that uses dynamo to charge them while cycling.
However, depending on my speed, current is fed differently to lights and they start to flicker. Therefore, I was wandering if there is a way to make a constant current source which...
Homework Statement
[/B]
Derive an expression for vc(t) in the circuit of Figure P4.13 and sketch vc(t) to scale versus. I attached a screen shot of the circuit for this problem.
time.
Homework Equations
V = IR
V = V0exp(t/tau)
The Attempt at a Solution
[/B]
I am trying to find the...
Homework Statement
Using the superposition principle, determine the current i(t.
2. Homework Equations
Zc = 1/jwC
Zl = jwL
V = I*R
I = V/Z
The Attempt at a Solution
First, I converted inductor/capacitor to impedance:
L = 1.5H > jwL = j * 10 * 1.5 = 15j
C = 10mf = 1/(jwC) =...
Hey everyone... I've tried to solve this problem with all kind of methods ,but I couldn't do it. I have tried to make an open circuit between R2 and R2 and then to find thevenin voltage and Ri but I have problem solving for thevenin voltage because of this dependent current source... Please give...
Homework Statement
Homework Equations
V=IR
Thevenin/Norton
The Attempt at a Solution
I am trying to find the Voc, but this circuit isn't making sense to me. So to start we can ignore the 9ohm resistor and that branch for now when Finding Voc so you are basically left with the square...
Hello,
I was reading about the differences between Current Source Converters and Voltage source converters.
One main difference was that Current source converters need to have a minimum DC power flow of 510% while VSC do not have a min flow requirement. It was also called a deadband.
Why is...
Homework Statement
Homework Equations
V=IZ[/B]
Zc = 1/(jwc)
Zl = jwc
w = 2(pi)*f
The Attempt at a Solution
I'm teaching myself circuit analysis, and it's been rough. Ultimately, I been able to mostly figure everything out, but I've ran into a wall with AC. The main problem I am having...
Problem:
my photo diode receives pulses of width 10ns150ns and repeating at rate of 1Hz50KHz
the current from photo diode depending on incident light can go from 10nA100mA, so i have two photo diodes to cover the dynamic range, what i want to do is limit the current from a photo diode to...
Homework Statement
Homework EquationsThe Attempt at a Solution
so when t=0, the capacitor is a closed circuit.
The Req of the circuit is (20k)(30k)/(20k+30k)= 12000 ohms.
U = I Req = (7.5x103A) (12000 ohms) = 90 Volts
so there is a voltage drop of 90 volts across the 20k resistor (R1)...
Homework Statement
Consider the circuit shown in Figure P1.68. Find the current i_R flowing through the resistor. Find the power for each element in the circuit. Which elements are absorbing energy?
V_source=12 V
I_source=4A
R=8 ohms
Here is a picture of 1.68
Homework Equations
P=IV...
Homework Statement
Check picture
Homework Equations
V=IR
The Attempt at a Solution
I thought I had this right, but then I started thinking about it and I'm not sure anymore. My thought was since the voltage was changing and the current was constant, that the source was a voltage source. I...
Homework Statement
In my Intro to EE class we have a homework assignment with the following problem:
I think I finished part a but want to make sure that I am doing the problem correctly before I move on to the next part.
Homework EquationsThe Attempt at a Solution
Homework Statement
given the circuit shown, find V1.
Homework EquationsThe Attempt at a Solution
see image:
am i right? Video says otherwise... I chose to use the superposition theorem here.
help appreciated,
regards,
james.
Hello,
I want to calculate the Thevenin/Norton equivalent of a circuit with a dependent current source.
I tried to analyse the circuit using loop equations but i don't know how to calculate the voltage drop across the current source.
Any help would be appreciated.
Hi everybody,
As part of my research at UCSD, we are trying to measure Hall resistance of some materials. And to do that we need to send an AC current. So I wondered how we could easily build an ac current source, probably based on opamp. I know there is the Howland circuit (current pump), but...
Here is the circuit. I have to find the voltage across each resistor and the current i1 and i2.
My attempts are the following:
By KCL,
i2 + i1 = 0.1 A
By KVL,
3  5  100i1 + 1100i2 = 0
∴ i1 = 0.09 A, i2 = 0.01A
∴ Voltage across 100Ω resistor = 0.09 × 100 = 9 V, voltage across 1100Ω resistor...
This is a problem from Foundations of Analog and Digital Electronic Circuits by Agarwal & Lang, I'm going through it by myself, I'm not in a course, so I'm depending on you friendly forum people for help! I really like this book but it has a lot of errors, perhaps this is another error.
1...
Homework Statement
Hi, I already asked a question close to this, but now I have different conditions.
This is the circuit
C_1 = C_2 \\
R_1= R_2
The current is an AC , and I would like to know the voltage at R_1 and at R_2
I made some progress but I do not really know hot to continue...
Hi.i know that a ideal current source has infinite resistance and it supply's constant current to aload connected across it. The current source doesn't have the infinite resistance in series to it but in pparalle. All is well until I think of this Norton's Therom. When we transform a voltage...
Homework Statement
I am supposed to give a thevenin equivalent circuit to the one posted in the picture.
Homework Equations
V=IR
KVL: "voltage drops around a closed loop sums to zero
KCL: "current into a node equals current out of a node"
The Attempt at a Solution
The part I'm confused...
Homework Statement
Which of the following are selfcontradictory combinations of circuit elements?
 A 2 Amp current source in parallel with a short circuit.
Homework Equations
KVL "the sum of voltages around a closed loop amounts to 0.
KCL "the current into a node equals the current out...
I know that van de graaff generator is a high voltage generator, i was wondering though if we can use it as a current source, if we get any resistor, connect the negative terminal to the generator "if the generator generates negative charge " then ground the positive terminal, then any charge...
Hello Everyone,
Best wishes
Am new to this forum.
Please need a brand new suggestion for digitally controlled constant current source.
I am designing this circuit for Plating thickness measurement.
I have tried a several circuits based on Analog pot but would be helpful if i get with Digital...
Homework Statement
Write the KVL Equation for the outer loop
Homework EquationsThe Attempt at a Solution
The question above is a sample I have made for such a condition. The goal is not to find the value, but only write the correct equation. If an independent current source is connected in...
This is more of a theory question than a homework question...but could a circuit consist solely of a voltage source and a current source?
What I mean is a very simple circuit with a voltage source of Vx and a current source of Ix, connected in series. No resistor anywhere.
Could this work? And...
Guys, this seems very trivial yet I can not come to the correct answer and I've searched everywhere.
I am asked to find the node voltages using nodal analysis. The trouble is I don't know how to express a current in a brach between 2 unknown voltages where there is an independent current...
How can current source be implemented? I think the source of current is the battery itself (due to potential difference). Plus current source has its own symbol. If battery is the source of current then does current source refer to the battery?
Homework Statement
the voltage Vc in the figure is always equal to
2 Relevant equations
The Attempt at a Solution
From kirchhoffs law,
Vc+4+5=0
Vc=9 V
will Vc always equal to 9 V or it will vary?
Hi I've tried to solve the following circuit using Kirchoff's laws but i get wrong results.I know that because I've got a different solution of the same excercise.I've attached the image.My question is what are the equations of Kirchoff's laws because I try this over 2 hours and I can't figure...
Some of my advanced chemistry students would like to try this pharmacokinetic model circuit outlined in an AAPT publication (Cock & Janssen, The Physics Teacher, Volume 51, Issue 8, pp. 482484 (2013)). It is a simple RC circuit, but I've never built a constant current source and am unsure of...
How are constant current sources different than any other source?
Also, would they really have a constant current in any situation? Even when backemf is induced?
Can anyone explain the use of a constant current source, and how different they are from other sources?
Hey guys,
I have been trying to design a constant current source that has a digitally controllable (μcontroller) range of maximum current outputs. Ideally the source would be able to be adjusted from .25mA to 2mA. The input voltage for the source would be in the range of 9 to 14 volts. Also I...
For this problem, I added in an external source, and found an expression for the external current in terms of ix. Then I divided Vex/iex to get the Rth. Then I did superposition to find the Vth. I had some troubles getting rid of the extra currents, particularly i3 and i2. I was wondering if...
Homework Statement
Image
Homework Equations
Current divider
The Attempt at a Solution
The only thing I see is that I solve for R1 and R2 for t < 0. Other than that I'm confused and not even sure I'm right about solving t<0.
Homework Statement
See images
In the first image, I made a circuit with the switch closed and then two when the switch is opened.
The bottom circuit is the Thev transform.
Homework Equations
The Attempt at a Solution
Let me first explain my understanding of the circuit. Prior to t = 0, the...