Dc Definition and 1000 Threads

Fellow Engineering Lovers, Being a mechanical with limited electrical I must turn to the electron masters for answers. I have a PM brushed DC 12 V fan motor on of a standard electric cooling fan on a car radiator. My calculation comes out to be about 90 watt. I also have PWM 12-24 power...

Hi all; I am trying to amplify a dc signal using the AD524 amplifier . I connected the input- pin (pin 1) to the ground. pin 2(input+) to 0.5V (The 0.5 came from a varibale resistor). pin 3 (RG2) was connected to G=10 (pin 13). Ref.(pin 6) was connected to ground. Pin 7 (VS+) 9V. pin 8...

For a simple DC motor like this: http://i1-news.softpedia-static.com/images/news2/How-Brushless-DC-Motors-Work-3.jpg Does it reach a constant rotational speed? I know that when a current flows through it, Flemmings Left HAnd rule causes a couple of forces that results in rotation. As...

Hi, When coil is excited with ac because of varying nature of current ,flux of varying nature will be developed in coil and because of varying flux emf will induce in coil. what will happen if coil is excited with dc? intially cureent will increase from zero to maximum and is...

Hello experts! I am the student of electronics engineering. I have an question related to AC and DC button in Oscilloscope. When I am performing practical then I don't know whether I switch oscilloscope output to DC or AC mode. When I ask to teacher they don't give me any satisfaction for...

What would you do? Would you increase or lessen the turns of the coils? Would thinner or thicker wire be better? Would you increase the size of each of the iron cores of each pole of the armature? How do bearings assist the motor? Would simultaneously using both a perma magnet and an...

Hello, I interesting in making a high voltage power supply for capillary electrophoresis. Not much power is required and the DC does not need totally noise free so I figure this gives me a lot of flexibility. I would love the ability to adjust the voltage at 5kv increments in maybe a 5-30kv...

Hello folks. I have an electromagnetics quiz tomorrow and I am kind of nervous. I can't seem to grasp the concept of induction, more importantly how it differs in AC and DC circuits. So in lay terms: Induction is production of electric current across a conductor which is moving through or...

I just got a adjustable dc power supply and I cannot figure out why it will not produce 1-2V at very small amps such as 10-20 milli amps? Is this not possible with a common dc power supply? I would greatly appreciate some help with this...

Homework Statement A simple DC motor consists of an armature placed between two poles of a magnet. The armature is rectangular and has dimensions of 90mm in breadth and 100mm in length. Magnetic flux density produced by the magnet is 0.5T. Number of turns of armature winding is 500. What is...

I only learned of AC-AC stepping up, i am just wondering if there is a possibility for a DC-DC Stepping up, for about a 4V to a 300V. If it is possible please help me out with this.. I was wondering if it is about converting DC-AC stepping up AC-DC, though the use of inverters. I am also...

i want to make a 5v dc power supply for microcontroller i know how to make it i am going to use a 220v to 15v transformer and then by using capacitor and 7805 regulator ic i will convert it to 5v my question is as in transformer pout=pinput (ideally) by decresing the voltage from 220 to 15...

Hi, I use brushless DC motors for my hobby things (planes, cars, helicopters). These motors have a special ESC which outputs a 3-phase AC current to the motor. These motors have stationary coils, and a rotary magnet array. The motors have an incredible torque for the size. I have, however...

Hi PF.. I am an industrial electrician (w/ a electrical engineering technology diploma) I work in a iron ore mine in northern Canada... we operate mining shovels. they are purely electric there are two motors used for hoisting the bucket, they are DC shunt wound motors. We recently...

Hello, an elementary question here. I am thinking about a BJT transistor amplifier circuit which has the usual AC coupling capacitors to allow the AC signal to pass while isolating the DC component. I understand that but my question is how is this decoupled AC signal represented on the actual...

Hey guys, I am working on my lab with BJT with a Common Emitter Configuration. One of the steps asks me to measure the DC Operating Point, however I am not sure what they want. What I think they want is for us to find the point VCE where the slope of the collector current vs VCE intersects...

What is it that causes pulsed dc into an inductor to turn into ac? Are their specific frequencies at which this occurs (i.e. inductors self resonance frequency)?

i have read that in high voltage transmission line dc is preffered on ac and i know all advantages and disadvantages but one main disadvantage that i cannot find was I^2*R losses which was the main reason why we use ac on the first place can someone please explain that?

Homework Statement While the voltage induced between the points P and Q is changing, which is the high potential end of the inductor? Explain your answer. P.S. sorry for the fail Paint job lol Homework Equations The Attempt at a Solution I know that in a DC circuit current flows from the...

Hey guys, I'm working on a project involving a DC motor. I'm in school for mechanical engineering.. Electrical problems haven't really interested me so this is the first I've ever really looked into it apart from studying basic circuits in a physics course last year. Anywho, the project: I...

https://www.physicsforums.com/attachments/39765 a) Calculate the current through the 5Ω resistance. Use '+' sign for the current directed from right to left, and '-' sign if the current flows from left to right. b) The magnitude of the potential at 'a' is? Please help me with the two...

Hello guys! This is not quite a homework, but anyway. Homework Statement I'm trying to figure out some details about the circuit below. The circuit contains two voltage sources. V1 is 5V 100Hz AC source, V2 is 15V DC source. I know I can analyze this circuit simply treating it as if there...

Homework Statement A certain op amp has the maximum offset voltage magnitude of Vos = 2 mV, the maximum bias current of Ib = 100 nA and the maximum offset current magnitude of Ios = 10 nA. The op amp is used in the noninverting amplifier shown in the diagram below. Find the worst-case DC...

Hi all. Good day to you all. i want to make one thing clear. In converter circuits, how to trace the polarity of capacitor circuit. Is it following the polarity of capacitor or follow the current flowing in it? I understand that the capacitor is open at dc. So it means it is like a brake part in...

Hello, I would like to know what will be the shape of the torque-speed diagram in braking quadrant. Many thanks

Homework Statement In the circuit shown below the current source has been switched on for a very long time. Find the DC current in the inductor and the DC voltage across the capacitor. The attempt at a solution I replaced the inductor and the capacitor with a short circuit and...

Hi, I have an interesting problem: most people use accelerometers to sense orientation and thus measure the DC output value. What I'm trying to do is sense higher frequency vibrations (3-10 Hz). The accelerometer will also be slowly changing orientation so the DC offset will be changing...

does bjt amplify dc signal? why or why not?

Hey there... We are working on one DC motor after it was overhauled. DC Boom Motor 100 KW for Portrek Crane We have performed Servicing, Re varnishing,Commutator skimming undercutting Setting of Brush.and test the motor on no load.Motor was running perfect without sparking. When...

Homework Statement Find the value of CSB(current source B) and determine the value of I. Homework Equations Mesh equations The Attempt at a Solution mesh: a -> Ia = 0 b -> 11Ib = -12 c -> 6Ic = 12 d -> 2Id = -8 e -> Ie = -CSB Ic = 2 A Id = -4 A then I cannot...

I have a push-button switch rated at 3 amps @ 125vAC which I want to use in a 12v DC application (my motorcycle). ((on ground line under continuous use {headlight})) Does the AC rating translate as 3 amp for 125v AC hence 375 watts 375 watts for 60v AC hence 6.25 amps or 375...

I am currently running a DC motor in an electric vehicle. A lithium polymer battery powers a motor controller which is connected to said DC motor to drive the car. The lithium polymer battery as you would imagine has a battery monitoring system on it. One of the conditions it protects against...

Hi everyone. I'm working on a project that uses 2 high-torque DC motors to move a system. The max current draw from each motor is 50 Amps, so the total current draw for the circuit is 100 Amps. The power for the motors will be coming from a vehicle battery, and will have to be routed to the...

Does the efficiency of a gearbox just reduce the torque output of the motor? Or does it also reduce the speed? For example I have a motor with 100 N*m torque at 100 RPM, it then goes into a gearbox with a 80% efficiency and a 2:1 ratio. So the torque would be 2*100*0.8 Nm and the RPM 100/2...

hello, a simple question: a circuit with a DC source and a capacitor (assume no voltage loses due to the cables etc..) there wille be nog energy loses during the charging of it, because there's no conduction in the whole circuit, so no work is done by de DC source now assume a AC...

[FONT="Georgia"][SIZE="2"] Hi to everyone :-) I'm new to this forum. I'm an engineer working in a core field. I need to design brush less dc motor of 30 W power, Inout voltage-13.5 V. I'm struck in winding design . Could anyone help?

Hello all, I hope you can fill a couple of holes in my understanding. As part of a school assignment I have investigated the relationship between torque and current in a DC motor. I have used linear regression and the linear fit is pretty good. I have done research on the relationship between...

This is not homework but I would consider it to fall in this category. I am working on a robotics project and wanted to simulate a PID controller before implementation. I need to find a transfer function for my motor for this to work. Homework Statement As mentioned above, I need to find...

What are the benefits of having Alternating current instead of direct current? I'm just wondering why we use AC instead of DC..

considering this relay http://my.element14.com/durakool/dm84-2012-35-5024/power-relay-dpdt-2co-24vac-8a-pc/dp/1557207" what does contact DC voltage meant? and to energize / activate the coil i need a 24v current to do the job?

Hello I am a EE student and was wondering if anyone had some suggestions on how to fix my inverter it's for a capstone project we are using a twelve volt battery and trying to get 120vac 60Hzs we can get 59Hzs from the curcuit intill it goes into the transformer then it changes to 177Hzs and...

DC Electric Motor Torque/Power Usage Hello Everybody, I am mid way through doing an electronic engineering degree, I fancied as a summer project to build 6 wheel search and rescue robot. Idea being to use wheel chair motors to get the thing going. The problem is I am not an mechanical...

Hello all- I'm not very keen on electricity but am hoping this question is simple enough somebody might be willing to help out. I have a device that runs on 120v ac. Inside the device, the power supply converts the current to 1 12v-, 1 12v+ and 2 5v+. I'd like to remove the AC power...

A comment in another thread led me to think about an experiment which can hopefully test the validity of the pointing vector theory for a dc current. I’m very unsure of the outcome of this experiment but what the heck. Here it goes: the Poynting theorem states E x H is power per unit surface...

According to http://www.aveox.com/DC.aspx" The way to calculate the output of a DC motor in kRPMs is the formula RPM of motor: kRPM = (V - RmI) / Kb V= Voltage Rm = Terminal Resistance I = Current Kb = Voltage Constant (V/kRPMs) This insinuates that an increase in amperage...

I am studying Electrical machine course on my engineering semester. Can you you people provide me links for animation pics or video for working of dc generator and dc motors? Thanks for your help.

I want to know the function of the two power amplifier ?

Im working on a model in SIMULINK of an electric drivetrain with an automatic transmission.. The overall goal is to develop an algorithm controlling controlling a CVT via factors such as current, angular velocity, etc. This may seem very basic to most of you, but i know that Output torque =...

Hi My introduction to Electrical Engineering is Like one hundredth of a starter But I am here to have some Help I want to Design a Pulsating DC power supply of 1K or more with micro or Nano Time constant I will highly Appreciate any kind of help and Guidance and also want to ask is...

I understand the difference between AC and DC, and i also understand how an AC transformer works... but I guess not completely. My question is why can't a DC use its emf to create a lower voltage current like AC can? Does the DC's emf accrue over time thus making its transformation short...