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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significance of GND in Bridge rectifier

simulate this circuit – Schematic created using CircuitLab In my book this diagram is used to explain about bridge rectifier and explain how it works in positive half cycle and negative ...
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59 views

+24V supply versus +/- 12V supply

In CMOS mix-signal circuitry, would it make a difference if I set Vdd to 24V and Vss to 0, instead of having +/- 12V supply rails? I know voltage is just a reference, but do the absolute numbers ...
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44 views

How to power a Arduino Yun with a 6V battery?

I would like to power my Arduino Yun board with the following battery: Arduino Yun has a VIN pin that represents the input voltage to the Arduino board. The official documentation says: Unlike ...
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1answer
23 views

Enc28j60 Power issues

I am having a weird issue with the enc28j60 controller and atemga8. I am trying to build this circuit: I am using this schematic to power up the circuit with a 9V battery: (all the capacitors ...
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1answer
50 views

AC Mains Voltage Indicator Design

I am a beginner in EE and I am just studying circuits at the moment, and I have this question about designing an AC Mains Voltage indicator that indicates the voltage level of AC mains by three ...
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1answer
50 views

What will be the value of Vo

simulate this circuit – Schematic created using CircuitLab This ckt comes as a question in our previous year exam. what will be current " I " and voltage drop " Vo " . It'll be very ...
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1answer
49 views

In any circuit we can always control the input power? [on hold]

In any circuit, we can always control in voltage and current? We can stabilize them any value we need, given a good power source? Also, we can increase voltage in a circuit without changing current ...
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1answer
79 views

Voltage on circuit input different than on power supply

I'm using a really good 5V-35A switching power supply to power some mini PCs (Cubieboards if that matters) as below. simulate this circuit – Schematic created using CircuitLab The weird ...
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3answers
171 views

Why is 4.096V so often used as a voltage reference?

I get that each mV is equivalent to a bit in a 12-bit ADC, but why is 4.096V used so often? I've heard of this being from a "bridge". What does this mean and what is the historical significance?
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3answers
846 views

What simple IC can I use to extract 500ma from a computer USB port?

I have very small and simple electronic projects that I power up using the USB power connectors plus a resistor. For one project I require to use more than 100ma, however the USB port requires an ...
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3answers
83 views

Shunt Resistor on output of Voltage Regulator? [on hold]

I was looking through a popular circuit on Sparkfun and trying to lower the power consumption of the device. I found that the outputs of their regulators are shunted to ground with a 300-ohm resistor. ...
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0answers
33 views

unknown amperage charger problem? [on hold]

Ok, so here's the thing. Our dell inspiron n7010 charger died (19.5v 4.62A, 90w), and we managed to get our hands onto some universal charger, which claims to give 120w and an array of voltages from ...
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1answer
66 views

High voltage drop across H Bridge [on hold]

I have a circuit built with the schematic below. When I connect it to the motor and turn on the power supply, the voltage drop is big. My power supply voltage is set to 12V but when it is turned on, ...
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3answers
989 views

Why isn't there a potential difference across a disconnected diode?

I know this question sounds silly, as if there was a potential difference a current would be created when the terminals are connected together and this would mean energy has come from somewhere. The ...
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0answers
46 views

Minimum AC voltage that causes nerve damage?

What is the minimum AC(50-60Hz) voltage that can do harm/nerve damage? I know that a few hundred volts (even 100?) has been documented to cause nerve damage that resembles a crush injury. I also know ...
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1answer
64 views

Spanning high voltage between capacitors in series

first of all thanks for your time. I've studied a lot before to make this post but theory and real world rarely make a good marriage. I have 20kVAC of spike coming from an ignition coil (the one ...
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1answer
45 views

230v adapter on 220v socket [closed]

I live in Europe so 220v is the standard. I have 3 guitar pedals purchased from company called Digitech. Each requires output of 9vDC and 300mA. Previously I have used an adapter of a less known ...
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2answers
143 views

Is it possible to carry over 20MW? [duplicate]

Is it possible for a series of conductors carry massive currents(100 kA) at voltages over 100V? Assuming there is massive cooling. How can power plants carry MegaWatts of power?
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0answers
19 views

matching impedance for two separate variable DC input sources [closed]

I have a tank circuit that I wish to power separately from two individual DC voltage sources. the first source is full-wave rectified fixed 12 VDC from wall power; and the second source is also ...
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0answers
49 views

Stable current?

A large conductor that carries massive amounts of current at extremely low resistance(micro-ohms), now back EMF is induced that is really large. Let assume V = 0.2 volts and -V = 100 volts, and I ...
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1answer
66 views

Mirroring (flipping) a voltage signal?

Which circuit can convert the input voltage signal to either output signal A or B as shown in the image below? Background info: {Update1:This is the signal from a Passive Infrared (PIR) Sensor ...
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3answers
79 views

What do we mean by “ground” in an electrical circuit? [duplicate]

What do we mean by ground in an electrical circuit? When we want to solve electrical circuits problems, we set a "ground" level which is mean that the potential on it equal to $0$. I wonder how the ...
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2answers
80 views

Can the output of two 15-amp motor drivers be hooked up in series to achieve a 30-amp tolerance?

I had a cheap 15-amp motor driver that I bought on eBay. You can see product details here. I was planning to use this motor driver to power my robot, which uses two 24v wheelchair motors. Then I ...
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0answers
43 views

Need help with design of level shifter [2 vdd, 2 gnd]

This is the first time I've run across a system design with these requirements and it has me stumped. I need a level shifter made of smd discrete components capable of shifting SPI SCK and MOSI ...
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1answer
132 views

Biasing a Non-inverting Amplifier

A signal that swings between -1V and +1V must be amplified with a gain of 2 using MCP602 and then biased by +2.5V, so it eventually swings between 0.5V and 4.5V. The amplifier only connected to 5V, ...
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1answer
99 views

Designing/looking for a circuit board for a vaporizer

I recently decided to look for/create a board for a vaporizer and have no idea where to start. I will probably end up programming the program in C or C++. To better explain this, I will explain the ...
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2answers
78 views

What is the maximum safe voltage for 1.5V and 3.7V gadgets of consumer electronics?

I know that most electronics for 1xAA battery accept at least 1.1-2V and for li-ion 3.5-4.3V. But what is probable safe maximum? Can I use li-ion with 20ohm resistor or even without it for supply 1xAA ...
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1answer
64 views

DMM Auto-Polarity / Polarity detection

I have understood how auto-ranging is typically achieved on a digital multimeter, but I'm having trouble finding an example of how (DC) polarity is handled. How does the meter know if a voltage is ...
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0answers
29 views

Non invasive voltage detecion (AC 230V 50Hz) Galvanic isolated

I am putting together a PLC (Siemens Logo o Simatic) that will monitor a control line that supplies signal voltage (230V 50Hz) to a industrial sized heating unit (GAS). The control line has in series ...
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2answers
43 views

Voltage sensing

I have a system that needs voltage monitoring. +12 Volt DC -48 Volt DC (-54 Vdc) The ADC chips I can find are limited with input voltage of max 5V. Are there ADCs capable of doing the higher ...
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4answers
112 views

How does a potentiometer work?

A lot of places where I've read explanations about potentiometers either go into so much detail or they're so superficial that I don't understand the actual concept behind it. How would you easily ...
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1answer
116 views

How can I limit the current in a 12v car battery to be safe for my 25a motor driver?

I have a 25amp Sabertooth Motor controller that can be powered by my 12v car battery. I have big 24v wheelchair motors attached to the motor controller. I do not know how much current that the motors ...
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3answers
59 views

Inverting Amplifier Not Giving Gain of -2.2

A LM358N op amp is used with R_f = 220k and R_i = 100k, which should give a gain of -2.2 in ...
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1answer
41 views

What does 'Braked Voltage' mean on a charge controller?

Here is the complete specs of the controller. Battery rated voltage: 12v Wind turbine rated power: 300w Wind turbine braked voltage: 15v Recover voltage: 13.5v Quiescent dissipation: <8ma ...
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76 views

Max voltage for Arduino ATmega328 VCC pin (not raw!)

I am thinking about getting both the Pro Mini 3.3V and the 5V boards. Example (but I may end up going generic, not sure yet) 3.3v: https://www.sparkfun.com/products/11114 5v: ...
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29 views

Input voltage for the ADC PCM1807

In the datasheet (http://www.ti.com/lit/gpn/pcm1807) of the Texas Instruments PCM1807 in section ABSOLUTE MAXIMUM RATINGS (page 2) it says Analog Input Voltage \$V_{IN}L,V_{IN}R,V_{REF}\$: \$-0.3V ...
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91 views

Regulated +5V drops when relays are switched on

A regulated power supply RAC02-055C/277 provides 5V to an Arduino driving 2 relays. The power supply is rated to provide 2W of power. Connecting a multimeter between one of the leads of the power ...
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1answer
111 views

How to keep voltage when using two diodes to run two irrigation stations?

My limited knowledge of electronics allowed me to solve a 'problem' that I had with my sprinkler controller. I wanted to run zones individually, but for some zones also wanted to run them together ...
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1answer
39 views

Battery charging using low power density piezoelectric device

I have a source of piezoelectric crystal which produce a sinusoidal output voltage of 2.5V and very low current of 1mA, I need to rectify that to store to battery as it is so small. I cannot rectify ...
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1answer
129 views

Is there a limit on the charge that can flow in a wire?

I assume when I hook up a 12V battery to a wire, all the free electrons in the wire move. If I hook up 24V, they move faster so more charge passes a area cross section for i=C/s. But in AC, their ...
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2answers
98 views

Is it possible to run a photodiode plus op amp on a 3V battery?

Naive question here. I've been toying around with the idea of making a simple light meter. From what I've read, photodiodes generally offer the best sensitivity and accuracy (as compared to ...
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3answers
211 views

My DIY solenoid does not work

DESCRIPTION: Hi there, I don't know lot about electricity and I`m having problems with my first solenoid-prototype, I tried to build it watching you tube videos. I have attached the pictures of the ...
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2answers
125 views

Understanding crest factor of a voltmeter

I was studying signals and systems and came across the crest factor which is defined as the ratio of Vmax of the signal to the rms value of the voltage with the dc component removed. It then proceeds ...
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1answer
33 views

Using 2 terminal band gap voltage reference

Specifically, LM385. Am I correct in assuming that a resistor is chosen to pass a current between 50uA to 10mA through the device from the PSU, and the reference voltage appears across the terminals?
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3answers
101 views

Voltage of Voltage Regulator changes when a Potential Divider is added

A Keithley 2400 Source meter is used to provide +7V. Using Fluke 179 Multimeter, the potential across the source meter leads is 7.00V. The source meter is then ...
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93 views

Choosing “widespread” parts

Many times I know the parameters of a part to choose and find hundreds of them, but I don't know which ones I would have to order, which ones I am likely to found in a local electronic parts store, ...
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99 views

Amplifying and Reading a 0-1 V signal into Arduino

I'm trying to read the (0~1V) output of a current transformer (CT) into the 10-bit ADC input of an Arduino Nano. The CT is sensing the L wire carrying 120V at 60Hz. ...
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59 views

Basic question regarding power consumption of different devices

I have current values for devices measured at different DC voltages. 4.2mA at 2.4V 68.8uA at 3.0V 44mA at 2.0V 65mA at 3.4V If I were to power them at a voltage of 3.6V and would like to ...
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1answer
45 views

Creating a powered USB hub, trying to drop my voltage from 12v to 5v (AC/DC converter I have outputs 12v)

I'm trying to build a powered USB hub without buying additional parts. So finding old electronics lying around the house kinda deal. Anyways I have a 4 USB hub that I took apart to find the PCB was ...
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1answer
78 views

Mysterious voltage drop then slows climbs back up when powered off

Ive built a simple circuit on some strip board, just a motor and a micro controller and LED and powered by 6 AAA batteries. The motor takes its power straight from the battery and the micro and LED go ...