Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [current-source]

An electronic component that sources current - if it sinks current it is called a current sink but both devices (sinks and sources) can be called sources. An IDEAL current source will supply current, maintain high voltage compliance (i.e. adapt its output voltage to match the network it is supplying current to) and have an infinite output impedance. In non-ideal implementations current sources have limited operating ranges and finite output impedances.

An electronic component that sources current - if it sinks current it is called a current sink but both devices (sinks and sources) can be called sources. An ideal current source will supply current, maintain high voltage compliance (i.e. adapt its output voltage to match the network it is supplying current to) and have an infinite output impedance. In non-ideal implementations current sources have limited operating ranges and finite output impedances.

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What exactly is a current source?

What I understood from the definition of current sources is that it is a source which supplies a constant current across a load no matter how the other parameters (like resistances for example) in the circuit are changed. Am I right? If I'm right,…
Green Noob
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What's the point of a current source?

simulate this circuit – Schematic created using CircuitLab OK. So I've been told that the current flowing into the current source (that is, into the arrow's behind) is the same as the current coming out of the current source (that is, out of the…
DLV
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Current Sources - Usage and Projects

I came across this page on building your own current source. What are current sources used for in real-world applications? The only places I've seen them used are textbooks. Do you have any suggestions for some fun weekend projects involving a…
J. Polfer
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Shutdown for LT3080 current source

I would like to use a LT3080 as a current source (see datasheet page 17 in Typical Applications Section). However, I need to be able to shut it off. Since $$I_{\text{out}}=10\mu\text{A} \times R_{\text{set}}/R_{\text{out}}$$ it seems just a matter…
apalopohapa
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Bidirectional Current Source

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…
Saad
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Source and sink current

If I am connecting ICs to both sides of a led matrix, the ICs need to be able to source and sink enough current to light the LEDs? Or just sink? Let me explain my question with an example: In this diagram, I select which row is illuminated on LED1…
André Wagner
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Unstable Feedback in Opamp+MOSFET circuit for Voltage Controlled Current Source

I'm attempting to build a 1 Amp LASER driver that can be pulsed (at ~10kHz) and gives control over current with a voltage (from a DAC, for example). I'd like to scale it up to 10 Amp pulses eventually. I tried this common circuit below on a…
Shubham
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Input Resistance: Why can you ignore current sources?

This may be a weird question, but I simply can't figure out, why you can entirely ignore current sources when calculating the input resistance of circuits. Here is an example (it's actually a small-signal model of a BJT-circuit): simulate this…
user24461
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Alternative to REF200 Current Source

I'm using TI's REF200 as a 200uA current source but need something cheaper with similar precision (temperature stability, accuracy, etc). I'm using this in conjunction with an INA337 Inst. Amplifier, giving me great accuracy but too expensive. This…
cdsiado
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Consistent LED intensity from low and variable voltage supply

I want to light 1 red LED among 3 (or no LED at all; never 2 or 3 simultaneously), using 3 output ports of a micro-controller (PIC18LFxxx or so). The catch is that I'm operating from a low and variable voltage supply Vcc_IN of 2.2V to 3.1V, and want…
fgrieu
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Examples of constant current source

I have read that photovoltaic cells and betavoltaic cells are examples of constant current sources. How are they considered to be constant current sources? The current in a circuit depends upon the resistance and if photovoltaic cells and…
Alex
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Does this current buffer analysis make sense?

I've transformed this circuit: simulate this circuit – Schematic created using CircuitLab In this one: I am aware that the input is V_in and the output is the current which enters in drain. I am aware also that here I have considered the V_out as…
thexeno
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simple current source calcuation

Which equation defines maximum current sink by Q1 in this circuit ? Which equation define maximum voltage at V2 at which Q1 enter linear mode of operation ( f.e. VCE ~ 0.5V) ? simulate this circuit – Schematic created using CircuitLab If I…
doodgraver
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How to determine current direction against a parallel current source? basic question

If you look at the node-voltage equations, you see that current of 2ohm-resistor is towards v2 node. How is that determined? If I change the direction the ends of the voltage on that resistor and make the current go the other way, only the third…
user168143
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How would one go about finding the Norton equivalent current for this?

I have found the equivalent resistance, however, I am finding trouble as to how I should go about finding the equivalent current source. The answer stated that the 12 ohm resistance was shorted, and that from "the load's perspective", the current…
TeraTesla
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