# Tagged Questions

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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### Do you have to put a voltage across a PV cell for it to work?

I'm studying about PV cells and I'm slightly confused. Currently, I'm learning this very simple model. I'm trying to figure out how exactly it works. Am I correct in saying that; You apply a ...
768 views

### How can I determine the voltage insulation rating of magnet wire?

As an extension of my previous inquiry into air-core chokes, I'm trying to determine the voltage insulation rating of magnet wire, without much luck. Few of the audio air-core choke manufacturers list ...
119 views

### Device can be powered at 6V or 12V, which is better? Why?

I got this camera and need to power it. Docs say that I can power it both at 6V and 12V, but laconically say also that it should be better to power it at lower voltage, so 6V. Can anyone explain me ...
1k views

### If voltage is measured between two points on a wire, with no resistance in between is the voltage zero?

I have a series circuit. Let's say the battery has a potential difference of 10 Volts. On two points of the wire before the current hits any resistors, I attach ...
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### Is this the proper way I'm calculating RMS?

I'm trying to calculate RMS value of the given graph. Am I doing this right?
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### Small battery cut off when fully charged

I am working on a small 1.2 V battery. I want the charging current of 7 mA to stop when the battery voltage reaches 1.5 V. What cut off circuit should I use ?
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### Do electrons actually flow when a voltage is applied?

It's said in books that a circuit is a closed path and thus that electrons come back to the source. If that's the case, what would happen when there were an earth fault in a circuit? How would the ...
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### PSpice VSIN frequency - how to set it in rad/s?

I know, that if I want to set FREQ, I need to set it in Hz, not in rad/s. I know, that 1 Hz = 2*pi rad/s, but how to do this in PSpice? What should I enter exactly? and btw. if I want to set VOFF ...
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i've Speaker with woofer requiring AC 12 voltage, and i have DC 12 voltage Adapter. However, speakers are working properly. but Can i use DC 12 V Adapther with the Speaker which is requiring AC 12 ...
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### Passive integrator circuit in PSpice

I'm trying to draw a plot of a passive integrator circuit. I think it's not correct as it should look like this: but mine looks like this (it's Vout/Vin on the right): I also don't know what ...
406 views

### Is a solar panel clamped to a battery a drain on the battery at night time?

I noticed that in the night time (dark) the voltage measurement on the battery was lower than in the day time (sun), measured with my voltmeter. I'm new to electricity, but that made me assume it had ...
585 views

### Headphone/Line out voltage for driving a LED?

I'm currently messing around with infrared LEDs and controlling my TV and various other devices from it. I have the spec and want to write a short Python script to generate these codes, and thus turn ...
184 views

### Most efficient way to convert 6 V to 5.5 V

My goal is to design a USB charger for my phone/tablet when I don't have access to the power grid. I've used a LM317 with a 12 V, 5 A·h SLA battery but it does not provide enough capacity due ...
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### How do I convert a signal of 3v to 2v to a signal of 0 to 5 v

I'm measuring input voltages between 2v and 3v (3v volts corresponds to a reading of 0 and 2v corresponds to a reading of 10,000) on the analogue in of my arduino. I would like to measure the voltage ...
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### Arduino+MotorShield v3: Jumper's position (PWR Ext/Sel Ard) using DC motors [closed]

Is it necessarily to connect an additional external power supply to the "Motor Shield" when using DC motors? Or enough to set the jumper on "Motor Shield" in "Sel Ard" position and connect the Arduino ...
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### Reading signals in a car 9-14.5v and translating to arduino HIGH / LOW

I have a project that requires me to trigger certain events in an Arduino based on certain electronic devices in the car being switched on and off. I essentially need to read a 12v HIGH state in the ...
453 views

### Op amp voltage regulator using N-Mosfet

I am trying to make a voltage regulator using an op-amp and a MOSFET: I'm really new to electronics. Why is $V_{DS}$ always so low ?
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### Small-signal input and output resistances of the circuit

I am given this circuit: And I am trying to determine the small-signal input and output resistances. I was either given or found all the following info for the circuit: VA = 110V β = 115 T = ...
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### On the circuit level, how does a graphics card, GPU, or other pixel plotting hardware to a display work? [closed]

I am thinking here on terms of electrons, electrical components, and silicon; nothing above that. Is the internal structure of a GPU similar to that of a CPU, i.e., registers to hold data, caches to ...
119 views

### AC rectifier and voltage regulator

I'm a mechanical engineer and my knowledge of electronics is letting me down please help. I'm looking to run a 1.5V led from an input signal that can vary from 0.3 to 0.5V ac. I want to make the ...
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### Is it possible to provide power using (effectively) a single wire?

I come to this question after a few thoughts on capacitors. A capacitor essentially transfers (and stores) energy using an electric field through an insulator. The plates of a capacitor are not ...
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### How to find τ in these circuits?

I know that $τ = \frac{L}{R}$, but what is $R$ in this formula? It seems to be the total resistance, but how to find it in the schematics?
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### DC 5V to 3.3V DC-DC Step-Down issue

TL;DR : The output voltage from my 5V DC to 3.3V DC stepdown seems to output 4.5V DC - why? Background: I'm trying to power an Airport Express from USB rather than a wall outlet. I have discovered ...
201 views

### 2 to 4 level converter in 8-QAM

i want to make 2 to 4 level converter for 8-QAM modulation, i'm going to use two digital input to get +/- voltage level, i want the output approximately like this,, when the input 00=-3 V , 01=-5 V ...
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### How much room for error (voltage and amps) do I have when replacing a power adapter? [duplicate]

I have a AC-> DC power adapter (similar to what you might find on a laptop) that has gone bad. The adapter is used to charge a 12 volt battery. I am working at a remote station, so I can't get a new ...
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### Electromagnet duty cycle

I have a project where I would like to use an electromagnet to lift an item for a longer period of time. I was looking at a magnet like this one: ...
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### Powering off USB - question about grounding

I have a female USB connector that I want to use to power a little piece of electronics I'm working on. I have a USB cable plugged into a computer with the socket on the other end and I'm using my ...
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### How to change the range of voltage?

I am doing a project to use dsPIC as controller to output PWM signal to control motors. I can use driver IC (I used L293D actually) to simply let motors to rotate, but I cannot control the voltage ...
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### Using a 5v voltage regulator - Capacitors necessary? Better options?

I am very new to electronics. I am learning as I go, and I haven't quite found the answers I need; when it comes to programming, I'm not afraid of mistakes as they happen constantly. With electronics, ...
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### Powering 17 meters of RGB LED strip - Worried about voltage drop and wire size

I'm modifying an IKEA Ramvik coffee table by mounting lengths of individually addressable RGB LED strip under the glass controlled by a Raspberry Pi. The LED strip is pretty standard; running at 5v ...
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### 10V from USB port

I want to connect a loading cell to the computer via USB port. The recommended excitation voltage of the load cell is 10V, and USB output is 5V. The current through the load cell is about 20mA at ...
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### Lower voltage and stay energy efficient

My circuit need to be plugged into a normal (canadian) 120V outlet. But everything on it is made to run 5V. I'm very beginner, so yet, I'm thinking of adding a bunch of resistance, but I feel that it ...
139 views

### Connect different devices (Ground/Voltage mismatch)

To begin with, I realize that voltage is relative but I do not get how to get a common ground so that everything is relatively correct to go in and out of the chips. The picture summarizes the setup: ...
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### How could extension cord detection be implemented in Tesla Roadster?

Googling finds evidence that Tesla Roadster electric car can detect cases when it is plugged in via extension cord. Specifically this page lists error codes 937 and 9 meaning "extension cord ...
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### Voltage/resistors/series/impedance/meter

Assume you measure a power supply voltage through a series 1M OHM resistor and observe that is drops by 1/2 its former value when no resistor is in series. What is the input impedance of the meter? ...
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### Voltage Controlled Attenuator

I'm trying to create a DC voltage attenuator which linearly scales the loss relative to an applied control voltage "Vc". In other words, K = Vout/Vin is a linear function of Vc. Vin is guaranteed to ...
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### Built-in voltage [duplicate]

Hello all I have work on the following question and just wondering if you all could check to see if i did it correctly. The built-in voltage of a GaAs pn junction diode is 1.25 V when the diode's ...
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### Doping concentration in anode region

I'm stuck with this doping problem and can't figure out where to go with it. The built-in voltage of a GaAs pn junction diode is 1.25 V when the diode's temperature is T = 320K. The cathode ...
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### What voltage is put across the Tx+, Tx-, Rx+, and Rx- lines over ethernet?

I'm trying to figure out how to wire up an LED, probably controlled by a FET, for an activity indicator for ethernet. I'm not trying to make one that supports official error codes or anything, but ...
435 views

### How to build a voltage-controlled current sink / voltage-controlled resistor

I am trying to control a current through several current-mirror device (specifically the IREF pin on the TLC5940) using a single potentiometer. I've tried using a ...
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### basic math question about voltage, ohms, resistance

total n00b here. After working on several projects by copy & paste from other people's schematics and code, I'm finally digging in and learning some of the math to know what I'm doing. If I have ...
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### Compliance question

Q. You have +5 and +15 volt regulated supplies available in a circuit. Design a 5mA npn circuit source(sink) using the +5 volts on the base. What is the output compliance? This is what I've done: ...
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### Problem on output compliance?

What is exactly meant by output compliance of a current source? I've read that it's the range of voltage over which the current source behaves well. What exactly does behaving well mean? I've got ...
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### Warm voltage regulator [closed]

Why is my voltage regulator get warm while my car is not running "68 corvette" battery is also going dead, is it the regulator or another problem?
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### threshold problem on a Schmitt trigger op amp

I have the Schmitt trigger op amp on the below diagram. (channel A & B refers the oscilloscope probes on the following figures). The resistor values are selected to set the trigger threshold as ...
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### Voltage Converter's GND Problem

I am confused about the ground part of a voltage converter. This is a typical voltage converter. As you can see the the main voltage is 230V, and the output is 5V. Look at the output 0V, which is ...
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### Wireless transmission of energy through a layer of non-conductive material

Is it possible to effectively transmit energy by electromagnetical induction? I have a plate of nonconductive material (5-10 mm) and I would like to transfer electrical energy from circuit on one side ...
157 views

### transistor loop to limit the current

I am trying to implement the DALI TX/RX circuit below. The description says: The other transistor (T2) is controlled by the current flowing through the resistor (R1). If a DALI slave unit is ...