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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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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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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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39 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 ...
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How to implement OCV(open circuit voltage) method for battery using Look-up table?Li-ion battery

I have gone through a ocv method using look-up table,they have given below steps.can anyone suggest how to implement using any controller or circuits? Charge the cell to the full point. Discharge ...
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21 views

Deriving the Integral Voltage-Current Relationship of a Capacitor

I am having trouble understanding the derivation of the capacitor voltage equation in my circuits textbook. Here is the process they followed from the textbook My confusion is: when the initial ...
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Low voltage form a NAND logic gate then the state is high

I've been trying to learn how to use logic gates. I wanted to use logic gate to bump digital signal from 3.3V MCU to a 5V. I took a T74LS38D1 and mocked the solution using two switches connected to 3....
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33 views

Is the voltage supplied by an LCD backlight inverter in a laptop dangerous in any way?

It is my understanding that in a laptop, voltage from a low voltage (say 10V) battery can be converted into higher much higher voltages by way of inverter for an LCD display module. Is this voltage ...
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Solarpanal solarenergy [on hold]

Can any one give a little explaination of how and why we have to put solar panels in series and parallel how do we get to know what do we need at end as like more current or more voltage
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Bimetallic temperature switch not turning off circuit

I recently bought a bimetallic temperature switch (linked to amazon here). It's for an engineering project for school where we're supposed to use diodes and a temp switch connected to a DC power ...
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45 views

How to reduce transformer secondary voltage?

Trying to make a bench power supply. What would be a cheap easy way to reduce voltage (to protect the series pass transistor)? 3 Amp transformer has these terminals 12-6-0-6-12. No load voltage is 33 ...
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26 views

Finding the supply voltage, knowing the resistance and current

I am learning the basics of electrotechnics. I had this task for my university that I failed doing and I want to learn how to solve it anyway. Thanks for assistance! :) Here is the exercise task: I ...
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61 views

Basic Ideal Op Amp Circuit Analysis

I am trying to familiarize myself with operational amplifiers by going through this book by Sergio Franco. This is a basic question regarding the example given on page 16, which I am struggling to ...
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47 views

Summing up batteries

I am a little confused, shouldn't I take into account the maximum battery voltage when trying to add-up batteries in order to achieve certain voltage? For instance if I want to drive a 48V 1000W DC ...
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37 views

Connecting a Solar Panel and Power Supply in parallel, in order to power up a load

I am using a Solar Module to charge a LiPo battery. The current supplied by the solar module goes into a battery charger IC and from there to the battery. This works fine. Now I want to add an ...
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29 views

Voltage translation for vehicle throttle sensors

I am working on a EV car conversion and I'm replacing the original throttle pedal. The two throttle sensors of the new throttle pedal are different. That means the output voltages have a different ...
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Arduino: read different voltage values in a range from -12 to +12V

I would like to trigger different functions in Arduino related to the following voltage values: -12V, 0V, 6V, 9V, 12V (the range is from -12V to +12V). According to the value of the voltage read (-...
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39 views

Low voltage output on smartphone charging IC [on hold]

After a couple of hours using a smartphone heavily while charging I got a "voltage too high" message. After that I couldn't charge the phone again. When I connect the charger the smartphone shows the ...
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109 views

Why do our electrical utilities use transformers way over their rated KVA?

My parents' house and my house have different electric utilities, but both are rural electric cooperatives. We both have 120/240V (60 Hz) split-single phase service (this is in the United States state ...
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21 views

Charging drone's Lipo battery [on hold]

My drone's LiPo battery is 3.85V and 1800mAh so what is the charging power I need?
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45 views

How do I connect an oscilloscope to a power supply or function gen.?

I'm supposed to sketch a circuit for my class but the one thing that has me completely confused is the ground connection. For example: I have a breadboard with a 10V dc power supply and two ...
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39 views

Vpp of oscillation of LCR circuit

Edited: I'm having a trouble to estimate Vpp of a RCL oscillation circuit. I found a peak to peak inductor voltage (Vpp_L) varies with the different combination of LC, which makes sense because the ...
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3answers
56 views

Is rated current supposed to vary based on voltage?

Recently I have been reading a lot of datasheets and noticed that many manufacturers specify a current rating for their products (especially connectors) without specifying at what voltage the current ...
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1answer
18 views

What should be the voltage rating of bootstrap capacitor?

BST_1P is the bootstrap capacitor connection pin for high-side gate driver of TAS6422. In the datasheet it is suggested that, this capacitor should have minimum rated voltage of 16 V. What is the ...
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2answers
45 views

Decrease voltage in circuit

If I have 90 VDC 3.5 A, and I want to reduce to 12 volt, in excellent efficient the amps will be around 25 A. Can I use a 12 V L7812 regulator?
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44 views

How can I change the circuit or the current to effectively heat up the diodes based on their current rating?

I'm extremely new to electrical engineering, and I was experimenting with diodes in series. I soldered six 1N4007 diodes together, and I connected them to a DC power supply (RSR ET122) with a constant ...
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1answer
22 views

Necessary voltage to charge NiMH using Solar Panel

I'm trying to understand which voltage I need to charge my NiMH batteries so I can purchase the components to do this. Actually I have 2x AA Ni-MH 1.2 V 1900 mAh and 4x Solar Panel 2 V ...
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69 views

Can I test if a battery is connected to a circuit?

I have a 12 V rechargeable lead acid backup battery that is connected to a circuit. When the battery is not in use there is a constant 12 V applied for charging, and when the battery is in use there ...
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57 views

What is the maximum amount of ripple input voltage a linear regulator can handle?

Greetings fellow EE's: Referring to the classic LM78xx series, I notice there is no specification on the maximum amount of ripple voltage these devices can handle at their input terminal. So for ...
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18 views

Correcting for changing voltage drops in a reactive load off-line power supply

I am trying to make an off-line (230V) power supply without a transformer, using a reactive load (1uF) in the AC path. This is followed by a bridge rectifier, a series resistor into a linear regulator ...
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83 views

Have i understood voltage correctly?

I am not from an engineering background, so this may be very simple and stupid but: Voltage is the difference in electric potential between 2 points Voltage drop describes the reduction in energy of ...
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1answer
32 views

Calculate battery state of charge percentage

What is the correct formula to calculate battery state of charge percentage based on the battery type (12v, 24v, 48v and so on) and the current battery voltage. For example if I have a 12v battery ...
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20 views

Finding capacitive load of CPU with dynamic and static power

I'm trying to find the capacitive load of a CPU given the Voltage, frequency/clock speed (in GhZ), and static and dynamic power. From looking around online I have seemed to find several different ...
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116 views

Is there any difference between voltage drop and voltage across a component?

Voltage drop across a component describes the reduction of energy when current moves through passive elements, is this the same as voltage across? What about for capacitors, technically current does ...
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44 views

How to wire together 3 power supplies for 3 different pd rails with the same reference 0v

How would I wire together 3 bench power supplies to get potential differences of +12, +24 and -6V, all with respect to the same 0V? All 3 of the bench power supplies have positive, negative and ground ...
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The simplest and best way to design a current and voltage protection circuit for this case?

I'm working on a frequency meter project that takes a sinusoidal wave input from a wave generator. The wave needs to be processed by circuitry that will produce a square wave with the same frequency....
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Voltage problem: 220v to 120v, working 24/7 [closed]

I have an aquarium from America, and I live in HK. Is there a way to switch the voltage from 220 to 120, 24/7? Ps. I have filters and such. Thanks a ton!
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36 views

Current in a single terminal voltage source?

I know there can't be voltage without current, but how can I calculate the current in a wire if I only have the voltage and there is supposed to be no resistance?
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Multi-stage coilgun - power source?

I am building a coil gun and am considering making it multi-stage. I want to activate them all at once and keep them on until the projectile reaches each coil, at which point they would shut off. ...
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2answers
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Is my solution to prevent leakage between power rails correct?

I have two boards with identical comparator circuitry (shown below). I want to detect in each board when the other is plugged in. My concern (in the picture) is that when I connect the two boards if ...
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2answers
56 views

KCL / KVL Circuit Analysis

I have a question regarding using KCL / KVL to analyse the circuit below to find all currents and voltages. My question is : When performing KCL at the top centered node, what way should I assume ...
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9 volt battery in a 6 volt led cicrcuit [closed]

]3I have a 6 volt night light that has about 100 little led's in it. The battery housing fits 4xAA(1.5v) batteries (6v total obvs). I thought I was clever putting in a 9 volt battery when I ran out of ...
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1answer
19 views

Relay if powered with ac supply then turns adjacent circuit on automatically

I took the idea from the below link to build my own relay board. http://www.electronics-lab.com/project/toggle-on-off-switch/ I connected 3 of this in parallel with voltage. All seems well until I ...
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1answer
34 views

Modify a 1629 magic eye tube circuit to a 6E5S tube?

I've an EICO 950B capacitance tester with me. It has an aging 1629 magic eye tube. I have a bunch of 6E5S tube with me. Can you guys guide me with the modification? I know the first step to this is ...
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1answer
14 views

Can I use a power supply with the same voltage but a different amperage? [duplicate]

I have an old router with a 12v 1.5a rating, and its power supply died so I'm using a 12v 1.2a power supply. I have a MIDI keyboard with a 9V 500mA rating and I have a 9V 200mA power supply and one ...
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2answers
53 views

High resistance op amp

I'm making a simple op amp circuit to use it as a compactor. I connect the non-inverting point to a simple circuit and the inverting to a 3 volt dc supply. the circuit should compare the voltage at ...
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3answers
88 views

NPN transistor as switch (actual voltage readings)

I started learning Transistors with this tutorial from the Sparkfun website. The tutorial is good and pretty easy to understand. So I decided to put my learning to the test and assembled a simple NPN ...
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28 views

Voltage sensitive switch using CMOS voltage detector

I want to make a voltage sensitive switch which selects either ground or Vcc depending upon the value of Vcc. Here is a pictorial presentation: To detect the voltage, I am using BU4918 CMOS voltage ...
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Net Output current from two charge controllers producing different voltages connected in parallel to a battery bank [on hold]

I would like to know the effect of charging a 48 V battery bank from two solar charge controller sources (each charge controller is from a different manufacturer) whose outputs are connected in ...
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19 views

Voltage Ripple in Controlled Three-Phase Rectifier

I am analyzing the controlled three-phase rectifier circuit with the RC load (R and C are in parallel). The givens are: maximum line voltage Vm, output average voltage Vo, votlage ripple delta(Vo) (in ...
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Writing the Nodal and Mesh equations for large circuit and large supermesh

Here's my circuit: simulate this circuit – Schematic created using CircuitLab I have defined the node 'voltages' and the mesh current directions and the currents themselves. What I want to do ...