Dc Definition and 1000 Threads

Hello, I was considering a small project to solve an issue with PC case fans. If you have fans on the removable side panel, the wires to power them is quite a pain to disconnect each time you want to take the panel off. I was wondering if it would be possible to take something like this...

A HVDC connection in a transmission network may reduce the system effective inertia due to the decoupling of mechanical and electrical systems. Could someone please tell me what does the above sentence suggest?

A practical DC motor armature is nothing but several "textbook DC motor" single armature windings bundled togheter and isolated together right? Like on this picture: http://content.answcdn.com/main/content/img/McGrawHill/Encyclopedia/images/CE152200FG0010.gif What really beats me though is...

With large wind turbines which have AC generators why do they convert from AC to DC and then back to AC before connecting to the grid, why not just connect straight from generator to the grid without converting? Very confused please can someone explain!

If we assume we are using an H-Bridge to control the average voltage across a PMDC motor, is it still necessary that we place a buck converter between the battery bank and the H-Bridge in order to step down the voltage supplying the H-Bridge? I've attached a schematic of what I'm reffering...

Hi, I am using a Human body model which I built for some simulation studies. I was trying to pass DC current through the Human body and though my Project completed the simulation successfully I got the below warning message. Can anyone please help me interpret it? The error log is as...

Hello, I have few questions about batteries and AC->DC adapters 1- in AC-DC converter: if I have a device required 12v and 1amp .. will it hurt the circuit if I connect 12v but more amps ? I heard it draw only required currents .. is that true ? 2- in batteries: why when we buy...

I've an emergency fan with an AC/DC button on it, but its manual doesn't say on which setting it should be charged. I've tried charging on both settings, and it can be charged either way. On the back of the fan it reads: "AC 220/240 50/60Hz 19w" The fan's box only says: "DC...

I think most of them are replaced by brushless types or Induction Motor with VFD (variable frequency drive). Is there some industries where they are still preferred today?

Hi there guys and girls I am new to this forum , so please have mercy. I am searching for equations to calculate the torque of a 3 phase brushless dc motor. Any info or textbooks on this maybe? Thanks Tommie Prinsloo

Hi All, I am looking for a sensing circuit, which can sense voltage signal between AC (85-265Vac) and DC (20-28VDC). Any idea how to design this circuit? Here is the main project: - looking for power supply circuit with Single Input terminal for AC as well as DC voltages. I would like...

Hey guys! Novice physics scholar here who's studying electronics on his downtime. I have some questions concerning AC and DC. If you guys could answer them (simplistically please, I still have a lot to learn :P) I'd really appreciate it. I'm reading here that 'AC costs less to generate then...

Ok, so I'm doing an experimental write up for an experiment on adjusting voltage on the speed of a simple DC motor, and changing the number of coils. I thought that I understood what I was saying but I've recently become a little confused with the concepts of torque vs speed specifically when...

Why is there a uniform current density in a conductor at DC. It’s my understanding that generally in a conductor, a sphere for instance, in a static situation, all charge is at the surface of the conductor because it the charges repel each other. So in a cylindrical conductive wire even though...

in DC there is a movement of electrons IE in a battery there is an excess of electrons chemically stored in one end that desire to travel to the other side of the battery where there are a shortage of electrons where do the electrons come from in a DC generated current ? if electrons do...

Hi everyone, Say I have a series DC circuit. The circuit contains a 100V DC source, a switch, a 1.5H inductor, and a 1nF capacitor (all in series). If I close the switch for 2uS what is the current at that time? Initially I thought I could rearrange V=L*di/dt to V*Ton/L = di/dt which would...

Hello, Is it possible to run heating and elements and other devices with DC supply? I have turned on Nickel-Chromium Heating wires with AC but is it okay to use it with DC supply? What's the main practical difference between AC & DC, as long as the voltage and current of supply is...

I am beginner in physics.I have question that when dc current flow they flow with apparent drift velocity so it appears that it should not emit em waves.But in actual current flow electrons are accelerated due to applied potential and also deaccelerated during collision so even they appear to...

Hi, I have been reading around about back EMF and their derivations for simple DC motors. However for some reason, the step between obtaining the total emf of the motor from summing the individual emf of the coils is not very clear. For example: Induced emf due to single coil: e = d∅_c/dt...

This might be a silly question for some but I was wondering how do I size a DC motor to move a weight and counter weight? Suggestions for a better design are also welcome. I want to build an enclosure with an automatic door (simple limit switches and an arduino to flip the motor on and off)...

Is there any way to take 12 volts dc from a car battery and have it go thru some components so that what comes out amounts to still 12 volts dc, but is limited to only 20 ma output? John

Hey! I am trying to figure out the best way to run a AC gear motor off a DC power supply. Any help would be greatly appreciated.

Hi I want to pass DC current through a magnet, essentially using it as connector. The magnet I am using specifically is Neodymium (NdFeB) grade N42. The DC current I would like to pass through it is 100mA ~ 150mA (3V DC ~ 7V DC) I would like to know if there is any downside to the magnetic...

Hello i have a little clarification to make for myself with the help of you:) So we know that electricity moves so fast through the wires because the charge is being "pushed" by the EM force which is mediated by the photon. Now AC systems no matter what the frequency have real photons...

Homework Statement Find the Fourier series representation of: f(t)={-t , -∏<t<0 f(t)={0 , 0<t<∏ This is a piecewise function. T=2∏ (the period) Homework Equations a_{0}=\frac{2}{T}*\int_0^T f(t),dt The Attempt at a Solution I need help only with calculating the DC...

Homework Statement You have been asked to develop a cross-country DC electrical transmission line to deliver 300MW of power to a town 200km away. This design is to only have a 2% loss (98% efficiency). If the line voltage is 600kV, what is the minimum diameter that the aluminum wire can be...

I designed the BJT amplifier below. After substituting in for the values of the actual resistances measured in lab, I reran the simulation. The hand calculation I derived for the gain was nearly spot on with what I was seeing in Multisim. Now, when in lab I get approximately the same value I...

Does a DC transmission line for a given amount of power, do better at higher voltage? I know power is the product of the Voltage and current. The logic given to me by one of my peers was that I2R losses are less if the current is low. And so for a given power, it would imply V to be higher...

Hello Frnds, I am presenting my engineering final year project. It is a 12 volt DC hydraulic jack. This jack is made to lift light motor vehicles and light commercial vehicles. Its capacity can be increased by changing some parameters. The project consists of a 12 volt DC...

Need to do something which requires adding a 2V DC bias to power coming out of the wall (120V, 60Hz), going to a motor. Basically need the 2V DC bias across the motor windings. Motor windings have about a 10 ohm DC resistance. I have a DC power supply that has a max voltage of about 50V...

1. http://imgur.com/UoUb27B 2. none? 3. not really sure what this question is asking. I thought that n=1 because its the fundamental frequency and the DC value should just be 120 V. I looked at some other questions and the answers were not found using that method.

Hi all, I have - 2 ICs that requires -10v and +10v - 1 IC that requires -5v and +5v How can I power them using one dual dc supply? Thanks!

My question has to do with Sputtering Silicon onto a substrate using DC without a Magnetron. The system in the lab I'm at isn't currently capable of RF sputtering and the status of the magnetron is unknown. Is there any way to use a sputter with DC to deposit Silicon onto a substrate? On the...

Hi, What hardware do I need to buy if I want to pulse DC power, say 12v through some regular coils with iron cores. Can I use a regular power supply connected to some other device? How would I pulse the output of the power supply?

I picked up a DC variable speed treadmill motor for a project that I am working on and I am having a hard time finding the information that I need. I need to drive a secondary pulley through a range of RPM up to a specific point. In order to pick the right size pulley, I need to be able to...

My choice of solid state Dc circuit breaker is the Mosfet, easily available( i got loads!) i want the mosfet to interrupt the circuit to protect the load from overvoltages This is what I've done so far, please help its not working the way i want it to. note to mods: i also put this...

My choice of solid state Dc circuit breaker is the Mosfet, easily available( i got loads!) i want the mosfet to interrupt the circuit to protect the load from overvoltages This is what I've done so far, please help its not working the way i want it to. the resistor connected to the...

Hi, I am trying to double DC voltage from 3v to 6v apparently this circuit works... charge in parallel discharge in series, can somebody shoot me down and tell it won't work please? Thanks Anthony

I have a problem how can i obtain a constant value of dc voltage from a capacitor(dynamo) to supply a device.. As we know if the capacitor is directly connected to the device, the voltage will drop and the device will not have enough voltage to function. what is a better way?

In DC motor or even in AC motor, if we use wooden frame and shaft, would it be advantageous than using Metal frame and shaft? Assume that would can with stand any temperature.

Hello I am solving DC conduction equation in Matlab. My equation is 1/r * ∂/∂r [r*σ* ∂V/∂r]=∂ρ/∂t My equation is 1D(only varies with radius) and time dependent. i am using pdepe solver.The space charge ( ρ) is the time dependent variable. But the form of MATLAB pdepe solver the time...

Hello, so I was looking at some dc to ac mechanical generators when a dc motor is used to drive a generator which in turn induced ac as was used for power conversion back in the day when semiconductor devices were not around yet.Well they had some drawbacks as the mechanical wear and etc. So I...

Homework Statement http://imgur.com/9fk2QXV Homework Equations V=IR The Attempt at a Solution I am stuck on part d, i have found the answers for part c to be 12,6 and 8 for I1,I2, and I3 respectively. For part d they seem to say that I3 is just equal to I1+I2, but i am confused...

Homework Statement Use the circuit shown to answer the following questions. At time t = 0 the switch in the circuit is closed. Answer the following questions after the switch in the circuit is closed. What is the equivalent resistance of the circuit given R1 = 5 , R2 = 5 , R3 = 4 , R4 =...

can you tell me all of the equations to find AC frequency? also, what is AC voltage? is it somehow linked to frequency?

Hi. I am curious about ways to sense the position of a rotor in a BLDC motor. I am familiar with hall sensors and back emf but am wondering if there are other ways to find the position of a rotor maybe more accurately. I had an idea about using a laser and a photoresistor around the...

1. An inductor of negligible resistance and an inductance of 0.2 H is connected in series with a 330 Ω resistor to a 12V d.c. supply. Determine: (a) the time constant of the circuit (b) the voltage drop across the inductor after two time constants (c) the voltage drop across the...

Computer brush fan as dc generator Sir, I am using renewable soℝurces like wind for my project.. I need to supply 1.5 to 2 v dc to my amplifier circuit and then to load... I am using computer brush fan as source ...it just gave output upto 2.5v in ideal state when i connected to multimeter...

I have attached the picture of the circuit. I'm trying to figure out the steady state voltages across the 2 resistors and the capacitor. V_s is given to be 10V DC. At steady state in a DC circuit, a capacitor acts as an open. When that happens, we shouldn't expect any current to flow...

Hello, All! This is a thread that should address my questions and evolve into a general discussion on AC and DC for the purpose of interest. My first question is: What did Nikola Tesla add to the field of electronics and AC? I've read all over the web two conflicting ideas 1) Tesla is...