# 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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### Wi-Fi Router Charger: is 100-240V input an acceptable replacement for a 220-240V charger? [duplicate]

My wi-fi router charger is broken and I'm looking to buy a replacement. The old one says - input 220-240V 50/60Hz 0.5A, output 12V 2.5A, efficiency level V Online, the closest I found has input 100-...
1 vote
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### Why does disconnecting the receiving end of a transmission from the sending end increase the voltage at the receiving end? [closed]

Some background information: I have a transmission line circuit (included below). The rated voltage is 63.639kV and the rated current is 325A. The characteristic impedance is 30.3 Ohms. I also have ...
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### Digital data transmission

Digital data transmission over computer networks is sending pulses of zero volt and 5 volts, per my understanding, to represent binary values which are then converted to their respective decimal ...
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### What's is this? An SMD Voltage Regulator?

I am trying to repair a fitness machine control PCB with an SMD component with unknown markings MVRB and LFNB. Could you please help me to identify this integrated circuit? From the PCB, it is ...
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### Why connecting two secondary windings together in an aiding dot-orientation parallel configuration will result in no output?

I need clarification on what would happen if the transformer is in aiding dot-orientation parallel configuration as shown below. Would that be the same as connecting two batteries, in parallel, as ...
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### Why would an in series-opposition center-tapped transformer not be used to drive a circuit?

I understand that if a center-tapped transformer is connected in series-opposition as in the image below, there would be no voltage across both circuit terminals. But can the individual voltage ...
1 vote
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### How to write the equation for the input side of a JFET?

I have been reading about the voltage gain of JFET, but I am unable to understand how to write the equation for the input side. Can somebody explain the method to write the equation for the input ...
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58 views

### How to vary output current by maintaining constant output voltage? [closed]

I want to control a proportional valve by keeping its voltage constant while varying its output current. Is there any way to achieve this
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1 vote
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### Addition of a voltage selector switch for a dual-voltage motor

I have a 3hp, single-phase 120V / 220 V, 1750rpm, 184t frame size, compressor-duty motor. I would like to include a voltage selector switch in the junction box, to select 30A 120 V or 30 A 220 V ...
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### How can I get a relation between flux and charge from memristor schematic?

I am simulating the schematic of the memristor and getting a response between current and voltage. From this, how can I get a relation between flux and charge? I also did not get the current and ...
54 views

### How do I add a secondary power source only if there is a primary one active?

Sorry, this question might seem super basic to some people, but I'm new to circuits. (I am learning on Tinkercad). What I'm doing is I have a power supply from an Arduino. When a button is pressed, it ...
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### Not just another USB voltage question [closed]

I have a travel razor that charges with a USB–A cable, but the razor is the proprietary Norelco type connector. So I thought I'd solder a USB–C directly onto the board in the razor. I checked the ...
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### How to solve this, when the time signal coming from the pulse generator output, likely square wave? [closed]

The signal is coming from the pulse generator circuit.
1 vote
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### Can I wire a 460V three phase heater (Modine model HE150) to my single phase 220V residential service? [closed]

If I used three 2 pole 220V breakers then added a return neutral to one leg in a delta configuration would it work? Do I even need a return neutral, or would two 2 pole breakers be enough and leave ...
62 views

### Pull-down resistor with LED on a logic input

Imagine I have the following circuit: A register (74LS377N) has the inputs connected to a bus. In the picture, BUS0 is pulled down with a 10k resistor, so if nobody outputs to it the register will ...
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### Circuit analysis to understand how this circuit works - PNP

I am trying to understand how to get values at midpoint_diode and also at OUT. I understand this circuit is to step-down the voltage from Vin to something that is lower and also it used to have a ...
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### How do I calculate time from pulse width?

I am looking into the LL4148 datasheet and notices the IFSM is rated for 1A @ pulse width = 1s and 2A @ pulse width = 1us. The goal is to calculate the energy pulse using E = IVt. The current and ...
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324 views

### Minimum voltage to register a 1 on 74HC devices

It must be late in the day or I am just losing it. I can't quite understand what this datasheet is saying for input voltage level. I am running my 74HC245 at 3.3V. I have the OE tied high, but ...
1 vote
63 views

### How to connect a 12V electromagnet to 220V power adaptor

I'm not very familiar with electronics, but I want to create a basic automatic pet feeder for my outdoor dog house. My idea is simple: a wooden box with a floor that drops at a set time, controlled by ...
154 views

### Voltage generation using 4 LEDs in series. Why does the voltage drop if I add a 5th LED in series?

I am making a device that doesn't use any batteries or outlet power. I need it to momentarily (<1 s) produce 5V DC or more after a bright light is applied to a hole with a 10 mm diameter. Due to ...
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### How to read BJT output characteristic

What's the propper way to read current graph / output characteristic of BJT? Is it useful if there is no DC load line plotted? I'm very beginner and I thought that only possible operating points lay ...
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1 vote
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### Reverse electrowetting on dieletric using air bubble displacement for electricity generation

I read this research paper and it uses bubbles to change the electrolyte and electrode interface, thus causing a change in capacitance as the bubble forms and exits the electrolyte. For reference: ...
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### Can dielectric coated metal wire mesh in electrolyte be a capacitor

Since capacitance is proportional to the area of the plates, why don't we just make a mesh out of metal wire (plate #1) and coat it with a thin layer of dielectric material, then submerge this mesh ...
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### How can I drop 24v DC to 12v DC with resistor(s) in my old tractor?

I have an old John Deere tractor that is 24v. It uses 24v to start. The lights are 12v. The charging output indicator lamp is 12v as is all other lights. The lamp has stopped working. I tested the ...
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939 views

### Absolute Maximum ratings of a device

In most of the devices I have seen so far, the absolute maximum ratings of the pins of the IC are given with respect to voltage. For example, the maximum voltage applicable on a pin would be something ...
1 vote
55 views

### Using capacitor with voltage rating close to input voltage

I am using a buck converter in my design. The input voltage is 12V and output voltage is 5V. The capacitor C331 and C332 are 10 uF 25 V in 1210 package. The inventory have already 16 V 0805 capacitors....
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1 vote
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I'm thinking about the example of two output jacks on the back of a computer, one for line out and one for headphones. I understand that the line out in generally an "unamplified" signal and ...
1 vote
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### Dropping the line voltage on an HH Scott 265A tube amplifier

I have a pair of monoblock tube amplifiers that were designed to run on 117VAC. My wall voltage is about 121-123V. What is the best way to drop the voltage down to an appropriate level? Option 1: ...
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### Making a device that can detect the salinity of water

This is my second year trying to attempt to make a device for Science Olympiad and I am confused on how to even start. I understand an Arduino is necessary but for the rest I'm lost. How do I detect ...
1 vote
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### What exactly happens when you connect two voltage sources in parallel? Why isn't it the same case when they are connected in series?

I have read that when two voltage sources of different magnitudes are connected in parallel (same polarities connected together,) a high current flows from voltage source of high magnitude to source ...
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### Buck converter with external reference voltage?

I would like to have a buck converter that takes in a reference voltage, and outputs the same voltage. This is assuming that I'm giving it a Vin that's high enough to support the output voltage that I ...
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### Accelerometer output mA/g; how to get to mV/g?

Using a Q-Flex QA2000-030 accelerometer that has output of current. It has a scale factor of 1.2 mA/g. If I want to get the output as 0.1 V/g-- how should I go about making the change? Would an op-amp ...
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### Why does the voltage at the source side change even though it has no connection to the drain on this NMOS?

I was playing around with transistors and stumbled upon something I dont understand. I have the following circuit below: Where the NMOS used has a threshold voltage of 5V. This means there will be no ...
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1 vote
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### How much clearance do I need for a terminal block that will run at 240VAC, 10A max?

To start off, I don't have any experience with designing PCBs for high voltage relays/switches. I'm currently designing a PCB that has a relay on it that will be used to turn on and off a device (like ...
1 vote
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### Square wave rectified output value calculation

I can understand the ground osc probe but with a hand osc I shouldn´t have that problem, I think. But It went even worst. Maybe it is a doubler¿?
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### Does this quesion have a solution? [closed]

Does this quesion have a solution? Is it possible to solve for any value or all four?
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### Confusion with negative voltages in this opamp circuit

I want to use a circuit like below to amplify a photodiode: (taken from this page) But it requires negative voltage. Can I use the following circuit I modified instead with a positive supply only: ...
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### Testing solar panels by covering one up out of 18 panels. If the voltage drops, is the panel defective?

The panels produce 31.4 V under load 45V open circuit, 4.1 amperes under load. I used to have a load voltage of around 271V for 18 panels in two strings of 9 in parallel. The voltage is now about ...
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### Solving for values in an NPN bipolar transistor circuit

simulate this circuit – Schematic created using CircuitLab I am trying to learn how to apply bipolar transistors in circuit but I cannot figure out how the textbook solved this one. The book ...
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1 vote
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### Why are there two rectifiers in series in a Terco generation and measurement of direct voltage section?

Why are there two rectifiers in series in a Terco generation and measurement of direct voltage section?
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### How to boost the output voltage of my 555 timer design?

I'm fairly new to the world of electronic design. I'm building an astable 555 timer with the limitation being I can only drive it with a 3v coin cell battery (design has to be lightweight). I've been ...
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### Configuring CPU with the reversed power polarity

My question comes from a pure curiosity. I initially wrote that it has no practical value, but in the process of writing I came to the idea that one (e.g. an intruder) can potentially use it to ...
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### Effect of limiting current of a lithium cell [closed]

I was curious as to what happens to the remaining amperage after the value needed has been dissipated from a battery. If I want 1 ampere from my battery at 4.2 volts and my battery is able to supply ...
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1 vote
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### How do basic voltage drop calculations work?

Consider two circuits which are supplied by a constant voltage source of 10 V. In one closed circuit I have one resistor of 10 ohm in series with the voltage source, and in another circuit, we have ...
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1 vote
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### Voltage Doubler capacitance calculation

I have an astable multivibrator that produces 5 V square wave input to the push pull and the voltage doubler part of the circuit. Now somehow the simulation works at 0.1 uF capacitors for the voltage ...
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### Would this Omron G5V-1 DC3 be suitable, even at my battery's 4v2 fully charged voltage?

I'm in a state of deep confusion and would appreciate some guidance. Please no sarcastic answers, I genuinely don't know! I've included links to the components in question at the end. So I'm designing ...
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### Change voltage range

I have a hall sensor AH49E and an ESP32 S3. The sensor's output voltage in my case ranges from 1.5V to 2.1V, which gives me only a 0.6V range. How can I change the voltage range to 0 - 3.3V?
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### How to calculate effect of different voltage on incandescent bulb?

How can you calculate the effects of running a 120V 7 watt lamp on say 80 volts, or any other voltage? Like what will the current draw be when you reduce the voltage? Is it possible to calculate ...
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