# Questions tagged [source]

Voltage and Frequency are typical absolute sources or references to drive other circuits. You have voltage references and frequency references. Current is defined by placing a known stable voltage across a known stable resistor. Frequency and Time measurements are often driven by a master oscillator such as a XTAL. Precision is defined by the accuracy of your reference sources, which determines how accurate your DVM/LCR/Frequency counter/O-scope are.

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### What does a voltage or current source actually output?

Current is the rate at which electrons flow through a circuit, and voltage is the potential "drop" between two points in a circuit. Do voltage sources output an unknown current, and vice ...
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### DC-DC converter possible by using Zener breakdown as input to transistor gate?

Suppose you have a DC voltage source that is higher than required, in this example let's assume one wants a 12V voltage source from a 18V source. Would it be possible to have a circuit, where the ...
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### Delta to Y with sources?

I'm wondering if this transform is possible: I tried doing a source transformation to change this to a regular delta network with two current sources going to nodes a and b, but wasn't sure how to ...
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### How to control unrelated circuit with a transistor?

I recently hit this issue that seems to be too complicated for google to find results for. Is it possible to control a different circuit with a transistor from a separate circuit? Below is a ...
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### Voltage drop drain to source n mosfet

Following simple test circuits online I hooked up a n-mosfet with V+ being 12 volts and the gate on a 20k pot from V+ to ground. There is a large voltage drop, even open source (to vom only) and even ...
1 vote
114 views

### Connecting two power sources to the same load

I'm going to start with a picture to illustrate my question: The resistor on the far right is my load (which will eventually be an Arduino or a battery which will then be connected to an Arduino) and ...
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### If the three-phase voltages are square waves, is there a neutral voltage in a balanced wye-wye configuration?

I am analyzing a wye-wye configuration circuit. Both the source and the load are balanced. The source is three-phase. Each phase is offset by 120 degrees. Neither the source nor the load is grounded. ...
1 vote
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### Small signal model

I would want to derive the output impedance of the following current source stage. I tried to convert it in small signal, could you please tell me if I'm wrong and how I can derive it to have output ...
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### Why is clockwise KVL done like this?

My task is to find voltage across the resistor of this circuit where all the 4 components are connected in series with each other. The given information are : V1 (t) = 100 * sin(100 * t) V, R = 100 ...
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465 views

### Power delivered by this dependent voltage source

How can I approach this type of problem? Which different methods can be used here? KVL, supernode, mesh-analysis, source transform. I tried using KCL on a node assuming its voltage V1: ...
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### High-frequency pulsed current source not pulsing full current as expected (Keithley 228A + MOSFET switching)

I'm trying to create a pulsed current source (square wave, 50%, 0-40 MHz, 2 A p-p). For this I'm using a Keithley 228A 0-10 A current source, and a custom board consisting only of a MOSFET plus driver....
298 views

### Alternate between 0 and 180° shift at regular intervals for a sine source during a .tran operation on LTspice

Is it possible to alternate between a 0 and 180° shift at regular intervals (say every second) for a sine source in a circuit during a .tran operation in LTspice? (I need to see the reaction of my ...
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### Three-phase, 480 V, 200 A supply, 480 V, 30 A load/charger compatible? [closed]

I have a 480 V, 30 A charger for a large JLG/lift. The power cord for the unit says it is only rated for 30 A. Could I still use this unit with my 480 V, 200 A source/disconnect? Would I need a ...
319 views

### Open-loop simulation of a voltage-controlled current source

Short summary: V3 decides the current going through R2. If V3 is 0 V then no current is going through R2. If V3 is 10 V, it will be approximately 50 mA. I want to do an open-loop simulation of this ...
68 views

### 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 ...
1 vote
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### Voltage-controlled voltage source issue with control voltage not affecting the output voltage

I am creating a voltage-controlled voltage source based on the schematic below: I vary the control voltage VC and Vs. (VC varies at X axis, Vs as different lines, 0~10 V). It resulted that VC doesn'...
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### Incorporate a voltage controlled current source in a circuit design

The voltage controlled current source as below where VC is the controlled voltage, I_probe3 (I_probe1) is the current controlled by VC How do I incorporate this voltage controlled current source in ...
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### Low impedance vs high impedance sources

Why is the USB adapter considered low impedance while the solar panel is considered to be high impedance in the below snippet and why do they consider it ideal to be powered from high impedance ...
• 2,389
1 vote
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### PWM-controlled current source to drive a 24 V proportional solenoid valve using an Arduino

I would like to implement a PWM-controlled current source to drive a 24 V proportional solenoid valve using an Arduino. What I need: Input will be 5 V PWM with 5000 Hz frequency, duty cycle will ...
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118 views

### ESP32 sourcing 20 times 5 mA?

I want to drive 20 optotriacs (MOC3063, each requiring 5 mA from the control side for the diodes in the optos). I want a 3.3 V ESP32 nodemcu board (wifi enabled as acces point) to control them. These ...
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### How to switch between two voltage sources?

I'm trying to design a circuit to switch a voltage source between 12V and 24V for a load that draws 400mA. Initially I thought I could use a SPDT analog switch but the ones that can tolerate >24V ...
1 vote
3k views

### How to determine which terminal of a MOSFET is source, drain or gate [duplicate]

I am a student and for my next exam, as part of the tasks, I need to identify which terminals (pins) of P and N type mosfet are gate, source and drain. I have an example photo here, but if possible, I ...
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1 vote
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### (AC circuits) Why do I need to use the superposition theorem when dealing with two or more different sources with different frequencies?

Consider: I know that the elements would have different impedances under different frequencies, but I can’t really visualize it. Also, is there another way to analyze the circuit (other than ...
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275 views

### Does an ideal voltage source go against Kirchhoff's voltage law?

Very new to electronics. Stuck on this topic: In a circuit with zero resistance an ideal voltage source of example 5 volts will produce 5 volts, since ideal voltages don't have an internal resistance. ...
252 views

### I am adding 1 ohm resistor with a coil in series and an connecting to a 25 W DC source. How to choose the correct resistor of 1 ohm?

I am adding 1 ohm resistor with a coil in series and connecting to a 25 W DC source. How to choose the correct resistor of 1 ohm? Is 1 ohm, 25W resistor is OK for this circuit? Please help. Edit from ...
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### connect two output with one kcd2 button

i have a power source that gives 24v output from 3 outs. I need to connect two outs to 1 kcd2 button. Is this possible? I need this because i have to power 2 boards from two outputs so that i dont ...
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170 views

### Instabilities in constant current sources at low load impedances

I want to turn my constant voltage source into a constant current, voltage controlled. For this, I used the following circuit. If the ERV error signal is connected to the UCT, the assembly functions ...
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### Do Output Voltage rails get an identifying symbol in schematics?

For example, I have a 3.3V regulator using 5V input from a USB port. I use that output 3.3V rail all over my schematic. Sure, I can read the entire schematic and see - yep, that's the output. But is ...
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### Source Transformation Finding TEC

I have been trying to find the thevenin equivalent circuit with respect to nodes a and b using source transformation. I end up having this setup. What would possibly be the next step I should do? Can ...
1 vote
257 views

### How does this current source work?

I am reading an application note and find a current source circuit as the following. Why the lower AD8610 is needed since the output voltage of the upper AD8610 is determined by VIN and the two 2kΩ ...
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### Will there be major negative side effects to hot-switching between two mains AC sources that are not in sync?

I am currently thinking about creating a "box" with a wall outlet, solar input and mains source input. This device will use a solar panel to charge an internal lead-acid battery. It's ...
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### Constant current source design considerations

I am designing a constant current source to drive a laser diode. I need it to be adjustable (from 0 to 100mA max) and stable enough as I will be using it as a light source in a Foucault mirror tester ...
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### Thevenin and Norton Equivalent Question about Current Division

Hello, I am asked to find the Norton equivalent of this circuit. So I did the calculations with source transformation. I did all the steps right but I am sort of confused on the last step to get the ...
3k views

### What load resistance will result in maximum power transfer - Art of Electronics

I am reading Art of Electronics book. There is a question: Here is an interesting problem: What load resistance will result in maximum power being transfered to the load for a given source resistance?...
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### How to create a 30 mA constant current power supply [duplicate]

I am a complete beginner in this field, so please forgive me if I write something stupid. I have a power supply that is pretty accurate, and I have been using it to power my projects. However, I need ...
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### Sinking and sourcing problem for buffer

Let's assume that I am using a buffer for a sensor output (V1) in the kHz domain. The output of the buffer will be ideally equivalent to the sensor voltage. There will ideally be no current coming out ...
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### AC circuit working principle

When a power source is AC (alternating current) one is a phase and the other is neutral. Does phase and neutral lines change their polarity over time or only phase line voltage and current up and down ...
265 views

### Proving that this JFET + Bipolar source follower give back a linear output

I was reading about this source follower and wondered how the bipolar transistor makes Vgs somewhat stable. I believe that what happens here is that when Vin is high more current flows through the ...
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### How to source/name a 20 pin 19 position usb 3.0 connector

I am trying to find the male end of the connectors found on many modern computer motherboards which are used to connect USB 3.0 from a case to the motherboard. These have 2 rows of 10 positions (so 20 ...
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628 views

### Behaviour of a capacitor in a load powered by a constant current source

It's said that capacitors are open circuits when there's a constant current, but it's also said that capacitors resist a voltage change. So which of these two holds true in the scenario I described in ...
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1 vote
80 views

### AL5810Q LED driver does not maintain a constant current

I am designing a controller for an LED matrix. The controller which must provide a constant 15mA where only ONE LED is turned on at a time. One of the features of this implementation is the high ...
45 views

### Smallest Footprint Source Only (No Sink) Buffer Solution [closed]

I'm currently in the process of designing a cable snake cable tester for recording studios that involves testing for connectivity between a large number of inputs. This involves using a ...
73 views

### With an extra flimsy cable length, the pump works...?

I have a 12V mattress pump that plugs into the car lighter socket. One day I had the need to use it in the house, so the first time, in the urge, I grab an old 12V adapter, strip the cables of the ...
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### Connecting AC and DC Voltage Sources in Parallel [duplicate]

I am still having trouble understanding how voltage sources combine when they are connected in parallel. Consider the following circuit below: If we assume that the wires connecting the resistor to ...
1 vote
3k views

### How to make 4-20mA Sink Generator to Simulate with PLC or other 4-20mA Instruments? [closed]

I want to test Pressure Transmitters without actually pressure available in LAB. So I want to make 4-20ma Simulator. I changed my Title to 4-20mA Sink Generator. As I am referring to 2 Wire ...
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### Source transformation brings out a different result compared to other methods

High schooler here that just recently found out about source transformations. I wanted to try it out on a previous circuit we did using the good ol' KCL/KVL/Node/Mesh methods, but somehow, it gave me ...
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### Why is a dc voltage of 0.3v is applied in order to check the closedloop1 AC response?

I have read the article related to current source “ opamp current source in simulation on prototype”. I wanted to know during simulation why a dc voltage of 0.3v is applied in order to check the ...
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### Do AC current sources exist and why or why not? For both actual and theoretical

I got confused when I encountered this problem on Chegg. https://www.chegg.com/homework-help/questions-and-answers/5-find-ac-current-source-iin-polar-form-b-find-vt--c-choose-one-source-current-leads-...
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