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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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108 views

Why do we need a chain of resistors to increase the voltage? [closed]

I did a workshop on SMT today and we made this board attached. However, what I don’t understand completely is the logic: why do we need 3 resistors to increase the voltage (on the boost part)? What do ...
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1answer
31 views

Replacement battery voltage mismatch tolerance?

I want to try replacing a proprietary battery in an electronic of mine as a first electronics DIY project. Thing is, the stock battery is 3.6V, and the phone battery I have on hand that I would like ...
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2answers
98 views

Cause of triode mode in MOSFET

My reference text introduces the MOFSET as follows: The text says the induced channel has uniform width as long as \$v_{DS}\$ is small, because in that case \$v_{GD} = v_{GS} - v_{DS} \approx v_{GS}\$...
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2answers
34 views

Run actuator at higher voltage and with lower dutycycles

I have an actuator which is rated at 12 VDC input voltage (0-15) with a maximum allowed duty cycle of 20%. The already existing voltage levels in my system are 5V and 22V, and since I am weight ...
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2answers
91 views

Is diode with forward voltage ~0.15v faulty?

I tested a diode model SB360 PFS which it showed about 0.15 forward voltage. The reverse voltage is zero. Looking the diode specification I read that Vf is 0.49v to 0.68v. So my question is if this ...
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1answer
107 views

What does “Run Power and Ground wires back to the Arduino” mean?

An Adafruit article showing people how to wire up an RGB LED to an Arduino UNO has the warning shown below on its page. For longer strips requiring more than 1 Amp, wire the power directly to the ...
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0answers
41 views

Off load voltage in npn transistor as a switch

There is transistor tutorial on sparkfun.com (https://learn.sparkfun.com/tutorials/transistors/all). I am wondering why there is 1.3 V drop depicted across the LED1 on the picture, since when the base ...
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4answers
145 views

If amps and volts can vary independently, how does Ohm's law actually work?

This is a very basic question as I'm just starting to get into things, but I've hit a roadblock with comprehending the definition of voltage as it relates to the relationship defined in Ohm's law. It ...
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3answers
98 views

What is line to line voltage supposed to meter at?

I'm pretty new to this but I know that in three phase power, when I'm metering line to line its usually at 208V, but I've been told that line to line meters at 240V. I don't know what would cause for ...
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0answers
40 views

JFET Voltage Divider design question

I've been trying to get this question done for a couple of days now and no matter how much I try I've been unable to get it done. Your help in this question is greatly appreciated.
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1answer
50 views

9V Battery Current Range

What is the range of currents that I can safely draw out of a 9V battery without damaging it? I am planning to design an experiment and I don't want to draw too much of current out of a battery and ...
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1answer
55 views

Power bank multiple output currents

I've been working on a simple power bank project that's been built using Li-ion batteries, the batteries are rated 3.3 V. I've implemented a charge controller which can efficiently charge the power ...
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0answers
56 views

How can you have high voltage and low current

I’ve read in another article, that you can have low current and high voltage simply by having a resistor in your circuit. From what I understand, current is the flow of electrons and voltage is the ...
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2answers
26 views

is there a relation between node voltage and the mesh current?

so i have a complex system of resistors i was able to calculate the mesh current of each loop . i was wondering if i can calculate the voltage of a node using the information of the resistor value and ...
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3answers
86 views

Crowbar Circuit Resistor

I have a crowbar circuit which uses an SCR with 100mA gate current shown below. In order to use this resistor value at 100mA it would need to be rated for 60W. Obviously here the resistor will pop. ...
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1answer
33 views

Replace 12V 2A centrifugal pump with 12V 1.4A peristaltic pump

I bought a liquid filling machine -http://a.co/d/8FMFWIU. There is a centrifugal pump model Dp 521 2Amps 12Volt. I want to replace this pump with a peristaltic pump. The pump is controller by a micro ...
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0answers
29 views

RLC series circuit with initial current

I'm trying to solve, for the voltage across the capacitor in the following circuit: simulate this circuit – Schematic created using CircuitLab The initial current in this circuit is equal to \$...
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1answer
74 views

How to calculate current through a resistor and LED?

Question C asks how's to calculate the current over the led and 3k resistor? Can someone please help me understand how to do it?
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0answers
40 views

What is the difference between voltage across battery and voltage across a resistor?

simulate this circuit – Schematic created using CircuitLab I am doing an experiment for a lab and I am confused as to what they are asking. They ask to measure the voltage across the battery, ...
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0answers
32 views

Source voltage of circuit with diodes when output voltage is given

Tried solving this using KVL, and solving to get the currents for the different parts of the circuit, however got stuck when trying to compute the source voltage especially that I'm unsure if the ...
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3answers
74 views

Capacitor max safe operating voltage

I'm currently making a power supply with a 32 volt AC out, so the rectified voltage would be 32*1.414-diode drop. The value comes around 44 volts. My question is, is it okay to hook up a 50 V rated ...
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2answers
69 views

Converting 12v to smooth 5v?

I’m working on a motorcycle here. I have a 12v battery to work with and a stator that produces (limited) power. I have a throttle position sensor that I believe needs 5v input and outputs up to 5v. ...
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0answers
28 views

Voltage Regulator with Reverse Voltage

I have designed a simple PCB circuit board that is powered by either the 5V from a USB, or if a battery is plugged in, powered from a 3.3V and 5V regulator. I am no expert in electronics, but have ...
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1answer
53 views

Laptop chargers that say 20V, are they for charging 5s?

I understand that 5s Li-ion should be charged at 21V (4.2*5) however the only laptop chargers I can find are 19V, 20V, and 24V. Each is relatively close to the value that should be used for 4s, 5s and ...
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0answers
60 views

How to Find Resistor for Maximum Power Transfer?

I honestly have no idea what is the best way to find RL for maximum power transfer in this circuit. What I do know, first and foremost, is that the RL resistor can be found as the Thevenin-...
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1answer
44 views

Use a European halogen electric light fixture in the U.S.

I brought a halogen standing light fixture home to the U.S. from Europe. The light worked using an adapter to convert the Euro plug to the U.S. plug, but the light was dim. I read that the wattage ...
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0answers
52 views

Finding Current in Parallel RLC Circuit with 2 voltage sources?

I've spent sometime learning about step responses for series/parallel RLC circuits, but this problem takes things a step further, since C seems to be in parallel with a series combination of RL and a ...
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1answer
61 views

Please check my DC / DC schematic. ST1S40

I want to make a voltage down converter to power my controller (Atmega328P). Input = 12V / Output = 5V (3A). As a converter, I use ST1S40. My connection diagram I took the circuit from datasheet, ...
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1answer
69 views

What's the magic behind inverters? [closed]

I'm having hard time understanding how inverter works and why it works. I mean why is it possible to power a say fridge (220V AC) with a 5v battery using a 5v to 220v inverter ? And since this is ...
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1answer
54 views

Sticking to high voltage DC Current

I heard that if you come into contact with a high voltage DC current, you will ‘stick’ to it until it is switched off. Why is this and how high does the voltage have to be for someone to ‘stick’ to it?...
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9answers
4k views

Does battery voltage actually get lower when connected to a load, or does it just appear to do so?

Sorry if Im wording this question strangely. I am using a 3.7V battery and my microcontroller monitors the voltage and goes to sleep if my battery voltage is too low. The issue is that it reads a ...
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1answer
53 views

Understanding some mistakes, when trying to find the Thevenin equivalent

I was asked to find the Thevenin-Norton equivelant, and I got stuck on some things that I can't quite understand. I don't know if i need to be more specific. What's wrong with the following? And why ...
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1answer
63 views

Does voltage drop with discharge?

Does voltage drop with discharge? Since voltage is the potentiality between two charges to re-balance (from my understanding). I mean, once all charges are equally shared between both capacitor ...
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2answers
103 views

Clarification on This Transformer Statement

Secondly, when the current starts to rise in the secondary wire, the magnetic field it generates is multiplied by the loop count. Obviously if we had lots of loops, a very small current will ...
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2answers
64 views

Garage door impulse generator volt free

I have a NovoPort (PDF) garage door opener and I want to control the door with an ESP32. One of the issues I am having is the warning for "Do not connect any current-carrying cables". In the photo ...
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2answers
90 views

How current and potential propagate through electrical circuits?

I have something of a theoretical question. In any given electrical/electronic circuit there seems to be an electric field developed inside (and outside the conductors?) to push the electrons in the ...
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7answers
194 views

Calculating the voltage drop of two Zener diodes in series? (reverse conducting)

I'm building a circuit powered from a 12V 55mAh (A23 battery). Needless to say that power consumption is a primary concern. The circuit is an ATtiny85 which is driving 13 LED's (in 5 groups). I ...
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1answer
36 views

Voltage Measurement with ST Microcontroller

I want to measure DC voltages from 1mV to 10V. I will be using STM32L053C8T6 Discovery board. I want to use 3.3V reference voltage. I know that if you want to measure voltages bigger than reference ...
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1answer
32 views

Synchronous Generator EMI

In the attached image below, I don't understand the text and phasor diagram that I have highlighted in yellow. Why does the induced emf on the armature winding lag the magnetic flux of the ...
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1answer
54 views

Is the “Volt” a measure of force or energy consumption?

A little confusion on my part. I see that a volt is the SI unit of electromotive force as the Wikipedia may show. I also see that One Volt is defined as energy consumption of one joule per ...
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0answers
34 views

How do you calculate average absolute value of a sum of sin functions with different amplitudes and frequencies?

I cant seem to find the answer anywhere. I remember there was a simple formula for doing this but I dont have the book with it anymore. Finding where the function is positive and where is negative and ...
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2answers
47 views

How does an op amp compare voltage?

How does an op-amp know where the ground is because the inputs are single wires, how does an op-amp compare them to a ground like this circuit for example clearly the op-amp is not connected to ...
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2answers
32 views

Lower wattage of IR bulbs permanently

I have two 90w/12v infrared IR bulbs which is put into a r7s sockets. From thes socket goes in total four wires which is connected to our power supply. We have set two of the wires in serial so they ...
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1answer
30 views

Whats the difference between a battery charger & Transformer to power a 12 V 3 A bilge pump?

I made a common mistake, identical to an earlier post "Using a 12 V 3 A bilge pump on a 12 V 8.5 A LED power supply". The pump was 3.8 amp so I purchased a 5amp led transformer, which just worked, ...
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2answers
26 views

In powering household devices, is the voltage preset and the amperage varies as needed?

When powering household devices, does a power adapter have a preset (or in some cases user-defined) voltage, while the device (while turned on) "selects"/draws whatever amount of amperage it needs at ...
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1answer
18 views

(pyramid xpa-240)if i had 10 voltage extra to a amplifiers what will happen? [closed]

I have a pyramid xpa-240 amplifier that does work with 110/220 voltage i want to know if it ok to use on 240 voltage? Or is the voltage to much for the amplifier?
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2answers
43 views

5V output on AAA Ni-Mh battery charger?

I bought a cheap Ni-Mh battery charger from Aliexpress to charge my rechargeable AA and AAA 1.2V batteries but before I plug them in, I checked the voltage on the charger terminals and it is reading ...
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1answer
76 views

Calculating a voltmeter reading

I'd like to preface with saying that I'm quite new to this. Given emf E = 9 V, and that both resistances are equal, R = 1 kΩ, ...
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1answer
63 views

Battery voltage drops to 0

I have this type of battery. When it was fully charged I read with the multimeter aroud 38-39 volts. Now I read 21 volts. The question is: When I connect the battery (discharged - 21,22 v) to a bldc ...
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1answer
54 views

How does distance between parallel batteries affect voltage drop/required wire thickness?

I'm looking to wire up an off-grid system. What I'm stuck on is battery placement. The likelihood is my batteries will need to be quite far apart (almost 2 metres). My question is how does this ...