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 it's 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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42 views

How do I adjust the current on this constant current board?

I bought this little thing. It gives a current of 17mA and i want it to supply a current of 1.5A to 2A. I noticed there is this current adjustment thingy. I have no idea what it is or how it operates, ...
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24 views

Why is this MOSFET KVL to find VDS not right?

There was an answer provided for this question I'm working on, but it seems that my answer was wrong. The sticky note has was the "correct answer" is supposed to be, but I don't understand why V-minus ...
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73 views

What is a Current Source?

In EveryCircuit, they have a component called a "Current Source". For example, here is a circuit I've created with a 2A current source: Is there a such thing as a 'current source' in the real world, ...
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39 views

High Power LED Circuit Design & Constant Current Source Question/Feedback

I'm trying to design a dimmable LED circuit board. It's controlled by Arduino with its PWM signals. I'm new to electronics so I have some question regarding my design and knowledge on it. I've ...
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481 views

Current mirror: is there a name for this NPN-PNP pair, and how does it work?

I'm looking at the schematic for the MC1460 voltage regulator. At the top it has three current mirrors, each with an NPN-PNP pair. Is there a name for that transistor structure? These pairs look like ...
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58 views

MOSFET for switching single LED

I try to design a cost-effective but still "reasonably engineered" way of driving a single white LED with a micocontroller with the following "specs": For the single white LED no extra boost ...
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49 views

DAC controlled LDO as current source - Pt.2

This is a follow-up question which references to "DAC controlled LDO as current source.". I am now trying to use the recommended LTC6363-0.5 as seen in the schematics. This is a fully differential OP ...
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72 views

Implementation of Current Source for a Current Mirror

let's consider this simple example of current source: It is a current source because each load I connect to it, it will receive a value of current equal to Vbias/R, which does not depend on the value ...
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94 views

Howland current source with voltage reference [closed]

I need a precision current pump for small ac signals(50uA) and i tried it in multisim with a howland topology. It works however i need the load to not be grounded but bound to a bias voltage. Here i ...
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66 views

Does a transistor change the source of current? (re: esp8266 and infrared transmitter circuit)

I'm trying to connect an infrared transmitter LED to a microcontroller (ESP8266/ESP8285). The infrared LED is a TSAL6200 with a forward current of 100 mA. The ESP8285 datasheet shows max current ("...
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DAC controlled LDO as current source

Currently I use a LT3083 as a constant current source more or less according to the datasheet as given in the first image. Instead of a single set resistor however is use a fixed resistor in series ...
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55 views

High power opamp-based constant current source circuit

I am currently working on a high-power 28S lithium-ion charger for EV. I'm on a constant current stage, so you don't have to worry about all that balancing thing, I just want a constant flow of 15A ...
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59 views

How to integrate current signal to be able to measure it with 50 ohm input impedance of ADC

Preliminaries I am using a photomultiplier tube (PMT) in order to amplify scintillator's light signals. Some of the studied scintillators have long decay time and poor light yield. That makes these ...
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19 views

controlling a sinking current with a positive voltage

I have found current mirrors like the basic one below often very useful. obtained from https://www.electronicsnotes.com/articles/analogue_circuits/transistor/current-mirror-circuit.php However, ...
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97 views

Circuit stable in the Bode diagram, unstable in step-response

I am designing a simple current control circuit and trying to simulate it in LT Spice. The circuit is not optimized for some real-world application, it's more a learning method for me to get grip on ...
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69 views

Led Matrix multiplexing: sinking/sourcing current + LED brightness

I am trying to make an 8x8 LED matrix (actually a bigger one, but for now it would be easier to discuss this more simplified version) and I have gotten too confused about a few things concerning the ...
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40 views

Basic Dependent Source Circuit Problem

https://ibb.co/JmBt71D Here, i added a image of the circuit problem. I wonder how to solve it. Firstly, i found a equation with respect to KVL for the left side of the circuit: -36+24*I+12*I=0 and I=...
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55 views

Source Measure Unit Design Verification

I’m in the process of designing a SMU for part of my senior project, and wanted to get a quick design review in before I did any layout for it. The SMU isn’t advanced in any regard; the only real goal ...
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71 views

Current Mirrors Design in IC

I was looking at a certain circuit in which there was the necessity of generating 3 DC current sources (10uA, 50uA, 250uA), starting from a given current source of 10uA. Let's consider firstly the ...
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72 views

Load current for LM317 [closed]

simulate this circuit – Schematic created using CircuitLab LM317 requires 10mA load to maintain regulation. the simplest option is to add a resistor, with a 10 ohm resistor as a load I get 16mA ...
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54 views

Choose precision current source mosfet and opamp

I am working on simple precision current source figure below, I need figure out how to choose correct Opamp and Mosfet to have most accurate result (Linear). So how do I calculate (or choose) Opamp ...
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68 views

Voltage controlled current source using op-amps

I have a sensor which gives a voltage output between 0V and 5V. I need to transform this sensor output to a current suited for a 4..20mA current loop. The thing is, the current loop doesn't have a ...
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189 views

Precision 1nA - 10mA current source

I need design a variable precision current source which able to produce 1nA to 10mA. The current output will be controlled through a Micro controller using a DAC. The purpose this circuit is to ...
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33 views

Superposition analysis with VCCS

I have just started doing electrical engineering course in the university. And I really don't understand how to treat those dependent sources when doing the superposition analysis of the circuit. Here ...
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Improve the frequency of Current Source Howland effect Op-Amp

I need help on a Howland Effect circuit with a current source purpose with an output of 600mA and a constant gain throughout a range of frequencies starting in 0Hz to 1Mhz. I am currently using an ...
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65 views

Unstable current source when reaching a certain threshold in current draw

I’m currently building a system for automated testing of ECUs. It consists of an ECU with regulated loads connected to its power outputs. The other IO of the ECU is connected to an IO expansion card. ...
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59 views

Is this current source (or mirror)? How does it work?

I'm trying to understand this schematic of this differential probe: There are several things I do not fully understand. One of them is this section: I would guess it is a constant current source (or ...
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59 views

Solving circuit with source transformation

Using the following circuit: How do you find the current i, using source transformation? What is the principle of it, and how to use it? All I know about it, is that you must simplify the circuit, ...
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43 views

Requirements for low voltage, low current MOSFET used in current source

I'm trying to determine the minimum requirements for a MOSFET that will be used in a op-amp based current source. I've hit Google and this site and looked at multiple pages, but almost always, they ...
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52 views

Why hasn't the industry standardized sink/source according to sensor/plc component type?

I know quite enough to understand how sink/source works when connecting sensors and PLCs, as well as how it works concerning the electronics components and circuit diagrams. What I don't understand is ...
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110 views

Why is usage of a current source preferable over a voltage source for charging capacitor?

I came upon this sentence in a paper concerned with dielectric elastomer actuators (DEA): Due to the capacitive behavior of a DE, a converter with current source functionality should, therefore, ...
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93 views

Current Source and Short Circuit

let's consider this circuit: How can I analyze it? Which is the expression of the current in the short circuit? Is it correct to split the circuit in the following way (I always did it when there was ...
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112 views

Why a source which has high source impedance modeled in general as current source?

Is there a practical example by using a circuit where a source better modelled as a current source if it has a high output impedance? I have been hesitating to ask here but couldnt figure out myself. ...
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66 views

Find the voltage across dependant current source

The question attached in the image : I have found the I in the left loop I=1.19A then I found the vo=-11.9 Here two questions in my mind : 1)does that mean that the voltage across the top resistor ...
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51 views

Thevenin equivalent with multiple sources circuit

Sorry if I may ask an idiot question, but its gonna be for few hours right now I have spent on this question. I am asked to find out the value of the voltage between points A and B, aka Uab, and I am ...
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83 views

Switching a current source on and off

For the measurement of the resistance of another PCB I am using a current source seen in the figure below. Now I can measure the voltage with an ADC. With the measured voltage and the set current I ...
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50 views

Reduce voltage/amperage from adapter to fit another device

Complete newbie here. So I got this old gaming console with the original adapter, which outputs 8.2V / 850mA. The cable connection with the body of the adapter is somewhat loose, though, so if you ...
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67 views

How to calculate voltage drops and power for a current dependent current source in series?

So the question goes as follows: For the circuit in the figure below determine: a) the loop current, b) voltage drops across all the resistors; c) voltage of the dependent current source, d) power ...
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56 views

Circuit Diagrams - 2 Input/Output Current Source

I have encountered a situation where I need to draw 1 controlled current source on a circuit diagram with 2 inputs and 2 outputs but I'm not sure what is the proper way to convey this idea. I can't ...
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163 views

Voltage Controlled Current Source - help needed

I am designing a voltage controlled current generator for the currents in a range from 0 - 2.5mA. The load resistance is within the range of 0 - 5k Ohms. I decided to go with difference amplifier ...
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45 views

Constant current source for an alternating magnetic field of varying frequency and constant amplitude from a solenoid

The project I am working on requires me to oscillate my sensor. I am doing this by coating a ferromagnetic material on the sensor and applying a sinusoidally varying magnetic field. I was applying the ...
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69 views

Constant current source with high Vce voltage

At the moment I implemented a current source with two FMMT560 for about 1 mA. These types allow -500V Vce. I expect startup peaks of 520 V which is too much. Are there any current sources which use ...
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73 views

Current Source Biasing with Diode Load

I am trying to replicate a circuit I found in the Art of Electronics (3rd Ed, page 229) but I am having issues. My load is a LED (Vf=~2.5V) and using a BC237 as the PNP (measured Vbe=~.675V). Using R=...
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77 views

Why nMOS transistors use 'Head' current source and pMOS transistors use 'Tail' current source as their load?

Here I am taking an example of common source configuration(refer figure). Generally head current source is used as load with nMOS and tail cuurent source with pMOS. Why can't be this other way around? ...
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84 views

Current Source and Current Sink

Excuse me for this simple question. Can someone tell me how this circuit works? In the video, it is said that, the voltage drop across the resistor connected to NPN/PNP will be only a diode drop. ...
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61 views

Is this polygon pour, how much current can it carry?

On my attached picture, I draw battery pins, (red square) component that want to current, (blue square, a component want to about 4-6 ampere) and way of current (black line). I have a some questions. ...
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61 views

When to use P-Type current source(using pMOS) and when to use N-type current Source(nMOS)?

I am referring to Prof. Behzad Razavi Lecture https://www.youtube.com/watch?v=GAvZLyii3aw&list=PLiDoPUX9nLkIw9EnIv_3K19wlcyJ6msYd&index=2 (Minutes 19-26) Prof. says to use nMOS when we draw ...
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51 views

Understanding current sourcing and sinking in TL2426 rail splitter

I have a 40dB active bandpass filter being powered off a single rail power supply with the TL2426 providing a virtual ground so I can get a dual power supply configuration. Currently, I'm having ...
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51 views

Proper voltages from same source

I'm building a small electromobile. I was planning on using a car alternator as the motor, however I'm now looking into buying a 48V 500W BLDC motor. The problem is I'm not really sure how to manage ...
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53 views

Stable current source with discrete components

The purpose of this is to compare and learn different circuit topologies, not use of the shelf solutions which obviously provide cheaper, simpler and better results. Considering this requirement (no ...