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Questions tagged [voltage]

Voltage, otherwise known as electrical potential difference (denoted ∆V and measured in volts) is the difference in electric potential between two points (adapted from Wikipedia). Voltage can be constant (DC) or varying (AC).

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what voltage will 7805 deliver as output if input is lower than 5 volts, lets say 3 volts

I am looking at the 7805 specs sheet and there is one chart I find missing. It is the relationship between output voltage with input voltage, specifically when input voltage is lower that 5 volts, the ...
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60 views

Equivalent circuits with one or multiple resistors

I am designing a circuit but I am facing a repetitive design that require too many resistors. The problem comes down to answering if the next two circuits are equivalent in terms of voltage drops: ...
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How to convert a wide voltage range (1 V-12 V) to 5 V?

I have an unusual application where the input voltage can vary from 1-12 V DC. This must be converted to 5 V @ ~200-250 mA. Since there are no available buck-boost converters suitable for this wide ...
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46 views

Reactive-Voltage (QV) Droop Curve and droop constant of Statcoms

I have a question about voltage droop curve of statcoms. I read many articles about it but I did not figure out how to calculate it and how to add droop curve in control systems. My system parameters ...
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50 views

Inductor current

Posting from my phone so pardon the terrible pictures. I am reading Daniel Hart’s “Power Electronics” I am still in school so my math skills are in the works and I have not seen everything I need ...
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53 views

24 VAC sprinkler valve using DC power

I am creating a circuit that includes a 24vac sprinkler solenoid. I need it to be portable so I'm planning on using DC current rather than AC. What is the best way to do this? If I just use straight ...
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1answer
57 views

LDO Voltage regulator output unexpected Voltage drop

I have a circuit using LD39015 1.2V Low Drop-out voltage regulator. . The value of VCC is 3.3 Volts. The goal is to supply an ADC channel with a constant stable voltage so I can use that to ...
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17 views

Phase voltage and torque of stepper motor

When I use a chopper type driver for drive a stepper motor how it effect the rated phase voltage? Is there any relation between rated phase voltage and running torque of the stepper?
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1answer
42 views

Reducing voltage for increased current through wire

I am wondering, if I reduce the voltage going through a specific sized wire, can I therefore increase the current? I am creating a series-parallel battery bank and it will output 7.4 volts at 75 amp ...
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1answer
85 views

Why is earth at 0 V with respect to phase?

In 3 phase transmission lines we have different voltages depending on how we measure it. Phase to phase voltage is going to be 1.73 times more than phase to neutral. So far I understand everything ...
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43 views

What is an expression for the output voltage?

simulate this circuit – Schematic created using CircuitLab Is this just a voltage divider principle and it boils down to sin(1000t)+sin(5000t) ?
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69 views

How can I calculate V1 and V2 in this circuit?

How can I calculate V1 and V2 in this circuit? This is what I tried so far: Calculate the voltage of R5 through voltage divider but I didn't find the way, I was looking about second OA circuit but ...
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Fast voltage translation from 3.3v to 5.7v

I need to translate a 3.3v signal to 5.7v with transition of around 60ns or less. Voltage translators such as the TXS0101 usually specify the logic high level for the input as VDD x ~0.65 (= 3.7v in ...
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How does the multimeter measure the voltage? [closed]

I am using the fluke 88 multimeter and I know this digital multimeter measure the voltage drops when measuring the current(ampere) in a series connection because the current flows into the multimeter(...
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2answers
109 views

How can I calculate length of wire, given its gauge and resistance?

As the title suggests; I am trying to calculate the length of a wire given its gauge and resistance in ohms per 1000 feet. I also have the amount of voltage drop, which is 1.1 V. ...
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Limit voltage from a Peltier module to 5 Volts

I'm looking to make a simple device to charge my battery pack when I don't have access to an outlet. The Peltier module I'm thinking about using is a "TECI 4905" module that at first glance seems to ...
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28 views

Calculate the voltage of the capacitor as a function of the time

The current is a function of the time. At t<=0, it is 0, and for t=>0 it grows at a rate of 20 A/s. I was able to calculate the voltage of the resistor and the coil by myself. When calculating the ...
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39 views

Need some assistance with making a battery box

I recently bought a 12v deep cycle battery 75 AH and I made a battery box following these tutorials: https://www.youtube.com/watch?v=cAErwLnsSIY and https://www.youtube.com/watch?v=torSEtjPZ2I (no ...
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133 views

Can I use a 220v soldering iron on 110v? [closed]

I ordered a 110v soldering iron, but received one marked 220v 60w with a usa-compatible plug. If I plug into 110, will it still heat up?
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74 views

How build a practical AC over voltage protection circuit for the input of an arduino board

The input signal to my board is an AC signal. My board will process this signal. My board can handle 3.1Vpk-pk maximum without any damage occurring. In the event that my input signal exceeds that I ...
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0answers
33 views

Equal Voltage, Higher Wattage

I am attempting to make a solar powered fan for my room. I am going to be using a 9V DC motor to spin the fan axis, and I have my choice between different 9V solar panels. My question is this: If I ...
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46 views

How do I find the inputs/outputs of an unlabeled transformer?

I’ve been trying to wire a transformer according to this schematic. but nothing is labeled on the actual transformer. There only only colored wires. On the primary side, the Blue and White wire show ...
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4answers
95 views

Multimeter, outlet and a Spark: the question of simple Voltage measurement

So I got a TekPower TP4000ZC MultiMeter. (Image source) It has COM port and two red ports: V-Ohm-etc. set at 600V Max and 500mA Max Fused 10A red fused port. Unlike other multimeters, there are no ...
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1answer
44 views

18v vs 12v battery question

I have a few 12v LED lights that run off cigarette adapters. I wanted to be able to use my 18v drill batteries so I pulled the guts out of an old charger and added a cigarette socket. The lights work ...
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96 views

Same LED different voltage drops with different supplied voltage

I have an LED with no specs for it. I decided to mesure what is the voltage drop across the LED, so I connected it to 5 V power supply and 325 ohm resistor. I measured the resistor with multi-meter, ...
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2answers
137 views

Simulating and Building a Multiple Feedback Band-Pass Filter

I have a distorted signal, and only want to allow frequencies between 95kHz and 105kHz. The input voltage is at 300mV peak to peak. Thus, I need a Pass Band of 10kHz and a Central Frequency at 100kHz....
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1answer
25 views

Trouble with replacing potentials for cc sources

I'm studying JFET transistors, and I'm having trouble with two things: the electric potentials on the following circuits. Writing the voltage Vds in function of Vdd, Id and Rd. For example, for the N ...
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1answer
130 views

Can a Single Supply Powered Op-Amp Handle Negative Input Voltage?

I have an input sine wave at 300mV peak to peak. I want to filter this sine wave to eliminate noise and distortion. I am planning to use the LMx58-N op-amp family, powered using a single supply: 3V ...
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2answers
50 views

Question regarding voltage and current

Please forgive me if this question sounds stupid but I am still an amateur. I was trying to power a DC motor a while ago and blew a transistor. Later I realized that it was rated for 200mA and I ...
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2answers
72 views

Can power transformers be used with higher voltages?

I purchased a Japanese transformer for a project I’m doing. It runs on 100VAC, not 120V, something I overlooked. Doing a quick search, Japan seems to use both 50/60Hz, based on the region. It’s 30 ...
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4answers
75 views

Non-inverting output of transistor circuit (at NPN base) is 0.69V max. why?

I tried to make a simple NPN transistor inverter so that I can use the strobe line of the parallel port to store data in two separate flip-flop IC's. (74HC174 and 74HC574) The IC that data will be ...
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1answer
51 views

Can an electrical wiring system carry enough current to create an EMP?

I'm writing a spy story of sorts and I demand realism in my writing. In one of the chapters an agent, working with remote hacking assistance, enters a datacenter to steal digital certificates. When ...
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55 views

Resistor for buzzer current consumption limiting calculation

I would like to know how did the circuit designer of the circuit in the image calculated resistor R100 value. My guess is that the 100ohm resistor is to limit the current to ~20mA. I have tried to ...
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1answer
404 views

Finding the Transfer Function of Spring Mass Damper System

I have been going through Ogata Modern Control Engineering book and working through several exercises to improve my understanding of basic control principles. I came across the following example which ...
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1answer
50 views

What is the use of series resistor in VBAT line of CAN transceiver?

In the application diagram CAN Transceiver TJA1043 (Page – 19), there is a series resistor in the VBAT line. What is the use of this resistor? How to select the value for this resistor?
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Using an LIS3DH at LiPo Voltages

The LIS3DH 3-axis accelerometer specifies that it's supply voltage should be between 1.71 V and 3.6 V. For most applications, this just means you are using either 1.8 V or 3.3 V as your main rail. ...
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How would you explain electron pressure across this circuit?

A book I am reading about electronics provides a diagram that depicts regions of high and low electron pressure, and thus voltage, across different sections of conductors in a circuit. Here is the ...
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1answer
25 views

Line - Line voltage with different phase angles, amplitudes and frequencies?

I know that the mathematical equation for the calculation of Line - Line voltage with same frequency, same Phase angle, same Voltage of 3 lines from the same generator. now, i want to know ...
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91 views

Voltmeter showing incorrect value when reading 12V battery

I'm building a battery box from a 75 AH deep cycle AGM battery, I have installed a voltmeter, but for some reason it doesn't display the correct value. I measured the volt with a multimeter directly ...
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1answer
44 views

Voltage sequencing on power up

I'm pretty new on PCB design, so my question may be obvious for some of you. I am wiring the layout of an LCD screen on a PCB using kicad, when I came to powering up, the datasheet of the AT070TN92 (...
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23 views

calculate time take to reach a threshold voltage based on the discharge rate of a supercap

I have a supercap as a backup power source for my embedded device whenever there is a power outage. I need to figure out the time from which point it would only take 10 seconds to reach 2.0V. What i ...
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2answers
86 views

LED's brightness difference in these 2 circuits

I have past exam's problem as follows. Suppose there are circuit A (left image) and B (right image). The question is why LED in circuit A is brighter than in B. The solution states that the Low-level ...
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1answer
37 views

Does a discharging capacitor in an AC circuit add additional voltage to circuit?

In an RC circuit with an ac voltage source, after the capacitor becomes charged and then the sign of the ac voltage flips, does the discharging capacitor add additional voltage to the circuit compared ...
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1answer
104 views

What is the physics behind width of the duty cycle in Arduino?

I was wondering if someone can tell me how Arduino changes the width of the duty cycle? How it produces an on-off pattern? I am looking for an explanation for modulation in this system.
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1answer
72 views

Diode OR circuit drive current

Why is there no drive current available from the circuit below when R is connected to 0V? The last sentance in this extract from wikipedia states that If R is connected to 0 volts it will have no ...
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1answer
39 views

Understand limit voltage and current

It could sounds odd but I am trying to find a switch for my inverter that is an isolator. My batteries are 12 V and my inventer can do over 5 KW, but I found a switch at 48 V, rated 300 A. If I use ...
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Under what circumstances would 5V@2.1A be lethal? [closed]

Besides obviously sticking an output of 5V directly to the heart. Are there areas inside the body where resistance in ohms is so low that a 5V electric potential would be fatal? I got into an ...
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77 views

Using Voltage Regulator (9v to 5v)

I’m trying to ‘hack’ a LED Fire-effect light bulb to work on a 9v battery. Using a multimeter I can see that the bulb converts mains voltage to 5v. I’ve got my hands on a 9v-to-5v voltage regulator ...
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21 views

Positive current source into negative supply

I am trying to use an LM334 as a constant current source on a power supply output. Because I want to have true zero output, and the LM334 operates at Vmin of ~1V, I want to put a TC7660 charge pump ...
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1answer
53 views

How to know voltage used on a data bus?

How do you find out what voltage is being used on a data bus for the high signal? On a small electronics I guess you can assume it will be 3.3v or 5v but what about other circuits, say in a car or on ...