Current source Definition and 136 Threads

Good afternoon PhysicsForums! I have a design for a voltage controlled current source. I've included the circuit diagram. The basics of the design is that I have an AC voltage and a DC Voltage summed then passed through a 1MOhm resistor to give me a current on the order of 1 microAmp. This of...

I found this constant current source circuit over at instructables.com. This circuit calls for 2N5088BU for Q1 and FQP50N06L for M1, but I replaced those parts with 2N2222 for Q1 and PHT6NQ10T for M1 because that's what I have on hand for simulation. I calculated R2 = 0.5/0.125 = 4 ohms, but in...

Hi - I am by no means an EE, so please be aware I may have some fundamental flaws in my knowlege. I have a battery powered isoluation unit that takes some voltage in and provides either a voltage or current source output. I am giving it 1V as an input and according to the conversion ratio...

Homework Statement This is a really basic problem, just a closed circuit with a current source and a resistor. We are meant to give the voltage and the current across the resistor in terms of the current from the source and the resistance of the resistor. (From the diagram, express Vr...

Thank you for any help that you can offer. Did I answer all of the questions correctly and thoroughly? Can you please find any errors, and point them out to me so that I can fix them? Homework Statement Show that : VB = 1.6V VE = 1.0V IE = 1.0 mA IL = 1.0 mA What is the voltage...

Homework Statement Problem #6 on the attachment Homework Equations The Attempt at a Solution I am stuck because if I do KCL at the node above the current source, It seems like all of the current should go back into Rs and none from the current source goes up to Rf

I'm trying to design a bidirectional current source for the purpose of measuring very small (0.0001 Ohm) resistances. I've come across this circuit: I can see that the transistors are there to 'boost' the current but I don't understand the purpose of the 1K resistors and the capacitor. I...

Attached is the model. Find Vx and Vy. The Attempt at a Solution The total resistance is 10 ohms, and the circuit elements are all in series. So 2 Amps of current is flowing in the direction of the arrow in the diagram across all elements, Vtotalsrc = (to the voltage from the current...

Homework Statement Homework Equations The Attempt at a Solution

Homework Statement Find Vout at t=0.782s (I already found Vout at t=0 s. It is 0 V.) Homework Equations V=IRThe Attempt at a Solution First I found Vs = 9*sin(14*0.782)=-8.989817V (with t in radians) Since Rpi is in parallel with the Vs, its voltage Vpi also equals to -8.98917 V. Since the...

Homework Statement Homework Equations The Attempt at a Solution First, I found all the impedance values. (starting from the left) Z1 = 1 / (j * 16E5 * 15E-9) = -j41.67 Z2 = 80 Z3 = 30 Z4 = j * 16E5 * 60E-6 = j96 I then combined Z1 and Z2. Z1 || Z2 = (-j41.67 * 80) /...

Homework Statement I uploaded the assignment it is problem 2 Homework Equations The Attempt at a Solution I really just want confirmation that my work is ok, and the command for a dependent current source in PSpice. The things that I found that are dependent, are very confusing...

Homework Statement Find i1 in the following figure, given: Vs=10V, I=1A, R1=5, R2=2, R3=4 Homework Equations KVL The Attempt at a Solution Applying KVL to mesh 1: Vs-i1R1-(i1-i2)R3=0 and i2=I=1A So, i1=(Vs+i2R3)/(R1+R3)=(10+1*4)/(5+4)=14/9=1.56 A But book gives answer as...

Homework Statement http://imageshack.us/a/img15/7218/sg2prob11.jpg Find the Thevenin resistance for the network(Sorry for the bad drawing, but that is a point like point / node A on the bottom where it's going out too and likely part of the load too, with a wire connected to the circuit, I'll...

Homework Statement 3 branches, Indpendents are a 15 Volt source (left most branch) in series with a 2 ohm resistor (current that flows from left to right though this resistor is 'i delta'), Middle branch contains a 5 ohm resistor in series with a current controlled voltage source (3 ohms * i...

Homework Statement Design a circuit based on the noninverting op-amp configuration that functions as a 1mA ac current source. Homework Equations Gain = Vout/Vin = 1 + R2/R1 The Attempt at a Solution I really don't know how to start.

Homework Statement http://imageshack.us/a/img26/4592/homeworkprintprob.jpg Find the voltage V0 in the network.Homework Equations V = IR Voltage Division: (Voltage across series resistor) = [(resistance) / total series resistance)](total input V) Current Division (for 2 parallel resistors)...

Hello, everyone, I have to design a constant current source for NTC, to have a more precise measurement. The NTC resistance used range is 1kΩ~13kΩ. I have tried several circuits, but the problem is the the current is not precise enough even in simulation. 1uA difference All the...

Homework Statement Homework Equations Anyone Know why If an ideal voltage source and an ideal current source are connected in parallel, then the combination has exactly the same properties as a voltage source alone? and If an ideal voltage source and an ideal current source are...

This circuit is really confusing me. I'm trying to find i using KVL and KCL. What's throwing me off is the short circuit effectively created by the inductor. I know that the whole circuit can't be short circuited because there is a current source that is preventing all of i from going through...

1. What is the difference between non-ideal voltage and non-ideal current source ( not in terms of circuit diagram like ideal voltage source plus series resistance )? 2. And how to decide that which source is used where and when ? ( because output of both is not constant)

Solve i_x when a=2. (See attached picture) This is my attempt (mesh current analysis): I made i1 be the lower left loop current. I made i2 be the lower right loop current. I made i3 be the upper loop current. Mesh1: i1 = 2ix Mesh2: -10 + 3(i2-i3) + 20i2 = 0 Mesh3: -5 + 3(i3 -...

Homework Statement Determine the voltage across the 2A current source Homework Equations kirchhoff voltage law (kvl) kirchhoff current law (kcl) ohm's law The Attempt at a Solution I'm new to the concept of a current source. I'm not sure how there can be voltage drop across the...

Homework Statement https://www.edx.org/static/content-mit-6002x/images/circuits/H1P2.79e52b492b94.png Homework Equations It's been a while since I've done KCL/KVL, could be that I'm being just being stupid. I'm trying to find v1, i4, and the power in all the circuit elements...

Homework Statement http://imgur.com/jsIWS Homework Equations Ʃ V_{n} = 0 Ʃ I_{n} = 0 v = ir The Attempt at a Solution I combined the two 2Ω resistors into a single 4 Ω resistor because they're in series. Then I tried to use KCL but I got 2 unknowns in one equation. 0.2A + \frac{Vi}{4} = I

I'm asked to get the noise signal from the constant current source I built with a 741 Op-Amp. I know I have to read it from the scope, but how do I go about the connections to the scope, and what other procedures must I follow to read the noise contribution? Pls refer to the figure provided in...

Homework Statement Find the thevenin equivalent circuit of the circuit to the left of the terminals AB. Circuit diagram is attacted below. Homework Equations The Attempt at a Solution I know that the thevenin resistance is 1kohm. I also know that the thevenin voltage is the voltage across...

Homework Statement An AC current source, 1 ∠0° A, with angular frequency 1 rad/s is to be applied to the input terminals of the circuit. Circuit is RLC, the current source is in parallel with a 1F capacitor which is in parallel with a 1H inductor which is in series with a 1Ω resistor. I...

why we take current source as a open and voltage source as a short in superposition theorem. is this is because of its internal resistance or any other reason exist?

Homework Statement Why does a transistor with a constant V_{B} (e.g. V_{B}=1V) only need V_{C} \approx 0.3V to act as a current source; If V_{C} < V_{B} doesn't that mean the transistor is not in forward active mode and thus not a mode we want to work in. Homework Equations The...

I am looking for a schematic diagram of a compact, temperature compensated, stabilized, high precision (accuracy within 0.5% or less) current source. The target current should be easily set to 100/150 mA, no matter if discrete or integrated solutions must be used. This project will be...

Forgive the title, I was unsure of how to briefly describe the problem. Attached are diagrams. Homework Statement The device shown in Figure P2.5 can be modeled as a current source in parallel with a resistance. When this device is connected to a 5[mA] current source, so that...

I need a constant current source ckt which can source current in the range of 0.1 to 1mA, with +/-1% tolerance, with Vcc 3.3v Any ideas? I found this - http://www.ecircuitcenter.com/Circuits_Audio_Amp/BJT%20Current_Source/BJT_Current_Source.htm But no info on tolerance. What happens to Io...

I am stuck with this problem,the dependent current source is creating a big problem for me, please help. I have attached the problem.

in the picture you can see the electrical network. in blue is the Current of each side of the electrical network. (did it with loop equations) i asked to find the Electric power of E and the Electric power of the Current source. so for E i found it and i got pe=11.4w. i also know what...

Problem description: The problem is Kotitehtävä 7 in the attachement. The idea is to calculate the output power (both P and Q) of the current source. Attempt: I know the current through the current source (obviously) and want to calculate the voltage over it to get the power. I have...

I don't know if this is the right place to post this question, but here goes. Whilst solving a circuit in class from a homework assignment, we arrived at a situation where a capacitor was in parallel with just a single independent DC current source. The question is, would current flow...

Homework Statement Given the this circuit calculate the voltage through the 3amp source? attached is a jpeg of the circuit. I wasn't able to get a good score on this one question quiz since this boggled me. Is true if I put current source that it will dictate the current of the battery...

Hello, So this thread is about using transistor as a current source. I understood the concept and all. But the main point of this thread is to finally seal my knowledge of transistor in saturation mode. We did an lab exercise about current sources, by biasing transistor with voltage divider...

I have a circuit with 3 meshes for which I have to find the mesh currents, and I have. However, I just thought that there might be a voltage drop over the dependent current source in the circuit, which would change the mesh current equations. The CCCS is shared by two meshes. When I did the...

Homework Statement Hey everyone. I might be overthinking this one, but I thought I'd post it. (sorry for the crappy MS Paint sketch!) I need to find the current through R3 Homework Equations V=IR \SigmaV=0 (around a closed loop) \SigmaI=0 (going into a junction) The Attempt...

hey guys, do ideal current sources have polarity? When I measure the voltage of a current source, it gave me a negative voltage. What does it mean? Also, can we use KVL in a loop containing a current source without converting it to equivalent voltage source?

Hi :smile: I have always thought of a current source as a very, very high voltage supply with a very, very large resistor, Rs, in series (I mean this large resistor would make series connection with the load resistor, RL). The larger the series resistor the less effect the change in load...

I've been going through some materials, and I was reading about electric circuits. From what I read I figured that the electric current is dictated by the current source, and it's preserved(in the respectable branches) by the emf. Is that right? Or my feeling that I'm way off is true :)

Homework Statement A practical current source has a current of 22 A. Loading the source with 50 \Omega results in terminal voltage of 390.3 V. Obtain the source constants, I and R.Homework Equations V=I\times RThe Attempt at a Solution In my clumsy picture below, shouldn't I_{load} be replaced...

If a circuit schematic contains a current source, is it safe to assume I(total) is that value?

Hello everyone,:wink: I am having difficulty understand the concept of current source and what it really is. I have written down below what I think of current source. Some things I said will be wrong and there could be possibility that some are not wrong!:-p Now you help me out please. Much...

why the internal resistance of energy source or cell is shown in series for voltage source and in parallel for current source? thanks.

Homework Statement In the circuit above, use R1 = 4Ω, R2 = 3Ω, V0 = 10V, and k = 1/5 Find the value of ix Find the power delivered by the dependent source 2. The attempt at a solution So what I assumed was that Ix+kIa=Ia so k=1/5 so Ix=(4/5)Ia then the equation for Ix would be Ix +...

Hey all, I am trying to create a type of current source to switch between 10 mA and 1.4 A at some frequency. I have an idea to use a BJT transistor as a variable resistor in a LM317 (or whatever the high current version is) but am not sure how to do it. Any suggestions? This circuit is to...