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.

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Adjusting the output current using a microcontroller

I have an LED driver. The current limit is set by the resistor RIADJ. Now there is 3.24 kΩ, which is equal to the current ~ 1 A. Also, the current can be adjusted by supplying an external current ...
red15530's user avatar
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Adjustable current limit control

How can I add an adjustable current limit control to the circuit below? Please explain with schematic. The output value doesn't matter to me; it is important for me to learn how to change and control ...
MReza Hadi's user avatar
3 votes
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Stability simulation - breaking the loop for a MOSFET - op-amp current source

The task at hand is to create a voltage controlled current source of 60 mA driving a valve coil (64 mH, 139 Ω). I am aware the MOSFET used is insufficient powerwise; it was a quick attempt to have a ...
Hyp's user avatar
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An adjustable (MCU) current controlled power source

Background: Source: Likely a boost converter IC (30v) Load: max 4mA (with 0.1mA accuracy), resistance varies (~1k-100k ohms). Need an MCU to control the constant-current output, ideally it can also ...
Dionysus's user avatar
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343 views

Limit battery charging current with simple resistor?

I'm designing a device with a small (400 mAh) NiMH battery with integrated charging from USB. I realise that as I have an MCU it makes sense to control the charging in software rather than worry about ...
Andrew Mowry's user avatar
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303 views

What happens when there is a current source at the drain and gate is GNDed?

In the circuit below, Vin = 0V and there is a 10 uA current source connected to 5V and the drain of the NMOS. Say there is a large resistance R1 at the source and the transistor's W/L is large and Vth ...
chaasv's user avatar
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2 answers
128 views

Constant current in a coil determined by voltage in the same coil

simulate this circuit – Schematic created using CircuitLab My aim is to design a circuit that includes a coil with associated resistance and inductance. When an alternating EMF is induced in ...
James Conway's user avatar
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2 answers
274 views

3 wire RTD with current source and INA

How would I connect a 3 wire RTD using current source and a instrumental amplifier for the output?
UKNP's user avatar
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3 answers
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Output current max and over current threshold different?

I'm new to electronic design. Can anyone tell me what is the difference between the output current max and over the current threshold in a power IC datasheet?(ex. LMZM33606)
Lân Trần's user avatar
5 votes
5 answers
3k views

Why do I get two different answers for the current through the 47 kΩ resistor when I do a source transformation?

If I replace the voltage source and 5 kΩ resistor on the left with the corresponding current source and resistor in parallel I get I = 192 µA (this is the correct answer as stated by the workbook). ...
zoghii's user avatar
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Combining sources. Calculate load current and load voltage. Calculate the load power, the power generated (or dissipated) by each source

Stuck on this question. Not sure how to calculate the voltage and power across the current sources. In question c the current from the 1A and 3A sources combine to 4A but I don't know how to find the ...
theonerishi's user avatar
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3 answers
458 views

How does a electrical device draw its rated current?

I am learning electronics and this question has been bugging me quite a bit. If I have a device, let us say rated at 6 volts and 350 mA, this means the device will work when there is a potential ...
Dixshant s's user avatar
2 votes
3 answers
413 views

Self-contradictory combinations, are my explanations correct?

Can a current source be in parallel with a short circuit? Can a current source be in series with an open circuit? Can a voltage source be in parallel with a short circuit? I have added my own answers ...
RK Eshat's user avatar
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250 views

Boost Converter With Constant Current Source

I want to design boost converter but not like general converter. This boost converter will be include constant current source feature. I designed buck converter version before ** I used LM2596 and ...
İbrahim Ethem DERE's user avatar
2 votes
1 answer
78 views

How does current flow when pairing a voltage generator with a current source?

in the following circuit : http://falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcZYA4BsB2ATNzZsEBOVA9EAZnKQUhAQFMBaMMAKAHcQAWb1EbJH4JeAoVE71RFQTz6VZkSenGD+K-tm50lASxAbKkbgdXao4ZeIrHT-...
for phone's user avatar
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1 answer
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How to transform between sources when they are in parallel?

Imagine you are given this circuit, and you want to transform the current generator into a voltage one, and then, find out the Thevenin and Norton Equivalents. At first glance, what you might think ...
Álvaro Rodrigo's user avatar
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PMSG connected to three-phase PWM rectifier - Simulink

I am implementing a controller for a three-phase rectifier in order to have a constant DC-link voltage. I have a PMSG which is connected to the rectifier and a capacitor (DC-link); I want to model ...
Pasquale Salucci's user avatar
2 votes
0 answers
57 views

Replicating the current output of a split-core current clamp

I have 6 inverters that read non-invasive AC current clamp sensors. Each inverter reads a different current clamp, all clamped around the same 230 V wire. While this works, it is quite messy. It was ...
Jay Dee's user avatar
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How to calculate voltages in op-amp circuits?

I don't know how to solve the following problems; I don't even know what the best way to start solving them is. Can someone help me with the calculation steps so I can then try to solve them on my own?...
VfB Stuttgart's user avatar
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Can I use a resistor to transfer voltage to current rather using transconductance amplifier?

The situation is I intend to transfer voltage to current to control a laser. The voltage comes from an optical phase-locked loop (OPLL). It is changing over time, so the current transferred from this ...
Madao's user avatar
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2 votes
2 answers
492 views

Voltage-controlled current source design problem

I am trying to design a voltage-controlled current source circuit. After some research, I decided to use an op-amp. In the circuit shown below, when V1 is 0.3 V, then Vr is 0.3 V and the current is 0....
mtoprak's user avatar
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DC current measurement in a battery cell

I want to apply a fixed voltage (around 1.1V) to an electrochemical battery cell in order to remove some oxygen from it due to parasite processes that affects the battery operation. At the same time, ...
bardulia's user avatar
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1 answer
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Voltage Shunt regulator NCP431

I'm trying to figure out how the voltage shunt regulator for my case is working. Below an extract of the electronic schematic of an isolated flyback board Ref NCP11187A65P45WGEVB from OnSemi which has ...
geek225's user avatar
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2 votes
2 answers
320 views

Supply-independent current source

In the given circuit, the resistor defines the current and it is connected at the source of M2 in this circuit. What will happen if it is connected to the source of M1? I don't see any problem, but I ...
prashanth's user avatar
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2 answers
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Need some component to allow 17 A pulses at 10 Hz, but clamp or trip if the current goes continuous

I would like to protect some equipment that gets damaged when it continuously pulls 17 A for more than 2 seconds. I would like to react to the current within around 1 second. The supply voltage is 48V ...
PigSpdr's user avatar
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3 answers
337 views

Resistor heating even at low power dissipation

I am designing a constant current source to power up a 10 W RGB LED (please see the circuit attached). Each R, G, and B consume around 400 mA maximum. I am designing my circuit at 330 mA. I have used ...
No Man's user avatar
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3 answers
496 views

A current source with PMOS

I created a voltage-controlled current source with PMOS. By changing Vg and Vd, I get the below curves. Vg is the controlled voltage. Vd is the source voltage. As we can see from the graph, the Vd can ...
kintaro's user avatar
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1 answer
918 views

Wilson BJT current mirror output impedance

I am trying to have a small signal analysis of a Wilson BJT current mirror to find out what is the output impedance. Already I know that the answer is $$R_o=\beta r_o/2$$ In the first step, I need to ...
chami's user avatar
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3 answers
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Using MOSFET as a voltage controlled current source

I am trying to make an electronic component that will do the following: Vc is the control voltage, it can change the current thru the device. I need Vx independent of the the current, that means ...
kintaro's user avatar
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How do I build an LED driver, where the input is a current source?

I'm designing a driver to interface four 7-segment digits (8V, 20 mA per segment) with an AS1115 driver (5V supply, constant current outputs). Following an internet source, I have the circuit shown ...
Ross Tucker's user avatar
-1 votes
1 answer
144 views

How does the attack / release element of this audio compressor function?

This is an audio compressor circuit based on (and designed by the makers of) the THAT 4301. U2B converts the AC input to RMS, which is then inverted by U2D. When there is no signal input to the ...
Josh Taylor's user avatar
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0 answers
202 views

How to determine current direction in node voltage analysis?

I have this circuit in which I'm required to find the Power produced by the Current source \$0.2A\$ : So I Add ground to \$V2\$ and did node voltage analysis such as : $$ \begin{aligned}V_{0}:\dfrac{...
Losh_EE's user avatar
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In master side HART protocol hardware: how HART voltage applied across sense resistance, can be received in slave side?

I’m trying to test a HART hardware both in master side and slave side , I’m using A5191HRT HART modem IC from Onsemi, (because only its HART modem IC founded in shops our city), the biggest ...
tech.elec's user avatar
0 votes
1 answer
169 views

High current shift register source (mic5891 alternative) [closed]

I'm trying to control 60 loads (solenoid valve with integrated control circuit,12v dc) requiring high side 50mA source current control signal using an MCU (3.3v) I need to control them individually so ...
Giuseppe Maggio's user avatar
1 vote
1 answer
138 views

Opamp current source - Impedance matching to a laser diode - MHz range current modulation

I want to modulate the current through a laser diode with the output of a (FPGA into R2R DAC)source. I am using an opamp to do voltage to current conversion as shown in the circuit diagram. The laser ...
Ravi Pradip's user avatar
2 votes
1 answer
177 views

High voltage current source improvements

Here is an old school MOSFET based audio amplifier. I unfortunately do not remember the source of this circuit. The upper rail voltage can be few hundred volts (MOSFET replaced and a few components.) ...
Damien's user avatar
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0 votes
4 answers
358 views

Bi-directional current source based on MOSFET or IGBT [closed]

I am studying a bi-directional current source based on precision difference amplifiers and the MOSFETs, which is described on the website https://www.edn.com/simple-precise-bi-directional-current-...
Rayonde's user avatar
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1 vote
3 answers
972 views

Current sources and voltage sources connection

We know that every voltage source can be transformed into a current source, and vice versa. We also know that voltage sources are connected in series and current sources are connected in parallel. Isn'...
terahertz's user avatar
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367 views

Current source in parallel with a short circuit

If a Dependent current source is placed in parallel with a short circuit, to solve our calculations would we assume that no current will flow through the dependent source and hence we remove it. For ...
Sherry's user avatar
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1 vote
2 answers
542 views

Howland current source for negative currents

I am currently in the process of utilizing the design of Howland in order to derive a source that is able to provide an \$I_{out}\$ between \$0A\$ and \$30A\$ at the output load \$R_L\$. As you can ...
Nick's user avatar
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2 answers
2k views

How to use dependent source in Proteus?

I am trying to determine the voltage at v1, v2 and v3 in a circuit like below using Proteus. ...
Becker's user avatar
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1 answer
426 views

Tellegen's Theorem Question

In Irwin's textbook on Basic Circuit Analysis, there is the following exercise: Up to this point in the book, the concepts of dependent and independent sources have been discussed, and also the ...
benjamin_ee's user avatar
1 vote
0 answers
211 views

Building a linear current regulator from a 12V 50A SMPS using a BJT array and a DAC

I have an application where I need a digitally controlled constant current power supply capable of currents up to 50A. I have made a digitally controlled constant current power supply in the past, but ...
king_geedorah's user avatar
6 votes
3 answers
3k views

Current source with MOSFET

In the circuits below, what does the 100R resistor do? In my understanding the 1K along with the 200 pF create an integrator topology to provide some stability but how about the 100R that feeds the ...
MrBit's user avatar
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1 answer
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Electrical circuit with 3 voltage sources and a current dependent voltage source

I have this exercise where I need to say if the circuit is possible to be connected. I'm in doubt cause we can't connect different voltage sources in parallel, but this current dependent voltage ...
Manaeiro's user avatar
5 votes
2 answers
282 views

Role of feedback capacitor in nanoamp current source

I am designing a nano-amp current source to drive a capacitive load, which can vary from about 50 pF - 200 pF. Analog Devices has a helpful application circuit in a datasheet (page 14) for the LT6082C ...
ron19's user avatar
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1 answer
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What affect peak current in an RL load rectifier circuit?

so I'm running a half wave RL rectifier in simulink. I don't have much knowledge. May I know what affect the peak current in the half wave rectifier circuit (the theory behind it) and how do I ...
Nazfull's user avatar
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1 vote
1 answer
250 views

Issues with bootstrapped Howland current pump

I've attempted to make a high-voltage voltage-controlled current-source based on this design from John Caldwell, but for some reason, it fails with high loads. The design is essentially a Howland ...
Christopher Moore's user avatar
2 votes
2 answers
82 views

Understanding the odd behavior of this current loop transmitter

In my assignment, I want to study this current transmitter circuit shown in the figure 1. The goal of this circuit is to output a constant load current \$ i_L\$ (denoted by \$ I_L\$ in the diagram) ...
Abeer's user avatar
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0 answers
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Why choose pmos over nmos

In the attached schematic, there are two branches. The branch on the left has a pmos + nmos transistor. The branch on the right has two nmos transistors. The sizes of the devices were selected such ...
Andrew Lees's user avatar

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