Dc Definition and 1000 Threads

Homework Statement Hi guys, on chapter 14 in Jackson's classical electrodynamics, problems 24 asks to prove that a dc current loop does not radiate, starting from Lienard-Wiechert potentials for the individual charges q. The distance between them is \Delta. We should move to the continuous...

anything?

How would one go about creating a speed control circuit for a brushless DC motor? I need two circuits to pulse DC in one direction, pause, reverse polarity, pause, and repeat. And I need the two circuits to be synchronized. I also need them to be opposite of each other in there polarity.(when...

I am using a DC push-type solenoid as the mechanism for shooting in my robotics project. I have to use 12V DC supply and have to shoot TT balls for distances upto 3-7 feet. The solenoid specifications suggest that it requires 60 amp current. How do i generate this?? Thanks in advance

Hello All, I am interested in constructing a small Hofmann apparatus for electrolysis (as a hobby), like this kind: http://en.wikipedia.org/wiki/Hofmann_voltameter" I am confronted with the choice of either using a bunch of 9V batteries, or some kind of AC/DC rectifier. As I am a...

I just wonder if the readers here realize a couple of things. 1. Basic Ohm's law is different than the Laboratory Ohm's law. 2. If a DC voltage is applied to a resister, an AC voltage is always generated across the resister. I hate to use 'always' but as far as I know it is this way...

hey guy I was wondering if there was any way to increase the amperage output of an ac to dc converter, it is a 120v ac input that outputs 13v dc at 3.42 A. is there any way to boost this output? P.S. Ya'll are the best, This is by far one of my favorite places to be on the web. kudos on a job...

quick and urgent:I need a DC MOTOR hi I'm designing a telescope mount and I need a motor which has less than 1 rpm I think I'm going to need (( 12 V DC 1/3 rpm )) please if you can help me !

Hi all, This is my first time making a somewhat complicated circuit, with the help of an online schematic. (http://www.dprg.org/tutorials/2005-11a/index.html ) My goal is to make a New Year's Eve ball-drop, which has a motorized controlled-release lit-up ball (on a separate power...

I've been studying the concept of operation of DC motors and there are a couple things which I'm having trouble with. When the rotor is rotating, there will be "cutting" of flux and according to Faraday's law an emf is supposed to be generated such that it opposes the change in flux producing...

Hi guys, I am a bit confuse on how to calculate the power of the motor, the torque and the speed of the motor shaft + how to find out the rpm. Basically, i want to buy a motor which will be able to travel 100miles with a min speed of 55mph and have a total load of the vehicle of 600kg. if...

Need help with circuit problem---I need to convert a simple dc circuit---approx 3 v---into pulses---perhaps as rapid as nanoseconds in betw pulses---however not yet sure of freq----also dc polarity would remain the same. Is there any component or device that could act as an ultra rapid on off...

Hello everyone, I have a few microwave caps rated at 2100 Volts AC and was wondering about their DC rating. I've heard that the DC rating of AC caps is usually 3-5 times the AC rating which seems to make sense but I'm not absolutely sure... If someone could please confirm or deny this I'd be...

Edit: Nevermind, I figured it out! I jumped the gun in making this post. I'm doing another problem from Schaum's Outline: Basic Circuit Analysis. The problem, #3.24, and its solution are found in this...

Hey folks, I have been thinking about doing a little hobby project for while, but didn't have the right knowledge to do it until now. Basically, I need a relatively small Low RPM, high torque DC motor that can be controlled by a microcontroller. I'm using the arduino duemilanove and have...

Is there an Optimal RPM for a DC generator?? I would like to ask if there is an optimal rpm for a DC generators? Or the faster it rotates, the more power it generates? The specification of the motor is as follow: http://www.mitsumi.co.jp/latest/Catalog/pdf/motorav_m25e_11.pdf

When current (DC) passed through a wire it creates a magnetic field around it, right? But if you placed magnets around that wire would they interact with the electricity flowing through the wire? If so, to what extent?

Hi everybody, This is my first message here and it looks like an awesome forum! :smile: I have a 12V geared DC motor and i am having a hard time figuring out how to maintain it's torque in from speed 0 to 150 RPM.. I know about PWM and figured it's not going to do it.. I am looking...

Hi, Looking for the SI Notation practices for Direct Current and Voltage Direct Current. We commonly use DC and VDC, but I wonder if that's correct per SI. I've looked through several guides and pdf's of SI Notation, and haven't yet been able to find the answer. Any help you can...

Can anyone help me convert 12v DC to AC for the purpose of measuring fluid permittivity in real time, automotive application? I'm new to PF and limited experience, so all the help/details you can provide are greatly appreciated.

Hi everyone. I came across this site yesterday during some targeted Googling and thought I'd give it a shot. I have a basic question about speed/torque curves for brushless DC motors. I would like to compute a speed/torque curve for a small three-phase brushless DC motor that I have. It...

How can i test an ammeter with ratings 24V (dc) 100 A with any load? This is just to check whether the ammeter works in the defined range. What kind of source should i connect to get a current of maybe 25 or 50 amps.

if you connect a DMM across a 120V peak AC signal what should be your output in DC mode??

i have an electric winch that runs off a 12v dc car battery and i want to run it off of 120v ac house electric current. is this possible, and if so how would i do it? thanks for any help

Homework Statement Hello, I have one hard exercise, that I can't do. Sorry for my English, it's not my mother tongue, but maybe somebody could help. To charge a battery with direct current I, it takes t=8 h. But they didn't have a DC supply, so they charged it with AC, that was rectified...

Just curious how electric motors work, specifically DC motors. I have some questions i would like to understand better. do the windings of a motor determine the required voltage to power it? Can a 110 volt ac motor be powered by a 12 volt dc battery without an inverter? Can a 110 volt...

please could you tell me that ,In dc equivalent circuit the resistors are replaced by cell.why is it so?though the resistor gives voltage drop where cell provides a emf then how does these are equivalent? thanks.

Does anybody know a good way to take the pulses from a rotary encoder and turn them into a DC voltage that would go up for clockwise turning and down for counterclockwise turning? I have the A and B pulses from the encoder, and that's about it as of yet. I also have these chips...

Hello, I have a small 9hp engine with electric start and a stator that puts out between 5-18 volts ac, it only has one wire coming out and would like to convert it to dc to run lights and charge my battery on a cushman scooter. any help would be appreciated...

how can i "pulse" a DC current at a rate of Ghz i need to pulse a dc current through a circuit in at 2.45Ghz. astable multivibrator style How might i go about doing this

Hello I need a little help here. I need to pick a DC motor to be used on a robot. I'm trying to calculate a minimum torque the motor should be able to produce, but I'm a little confused. torque = Force * distance = Mass * acceleration * distance (Ignoring moment of inertia created by...

Homework Statement From my Basic DC electronics text. 2 questions, multiple choice, but I seem to be able to talk myself into several of the options. I've combed the book thoroughly, and humbly come to you folks in sincere desperation. The resistance of an/a Inductor/Capacitor in a DC...

Homework Statement The dc reistance of a silicon diode for a current of 10 mA is closest to: Homework Equations Really not sure. The Attempt at a Solution Not sure where to start, this goes with a lab I just completed but not sure if this problem directly correlates to it.

Homework Statement If possible, find reasons why the resistance of a resistor may have a different value when measured with a sine wave signal (a.c.) than when measured with a d.c. (dirrect current) source. Homework Equations The Attempt at a Solution Please correct me if anything...

Hi everyone, Im currently doing my final year project and I need to calculate the torque of a DC motor so that I can replace it accordingly by another motor. Here are the motor's specification : 400V, 50Hz, 6poles, 200kW, 1400rpm, 371A Can anyone please help me sort this out. regards...

Why is AC more dangerous than DC even if the peak voltage of AC is the same as the DC voltage? This is a problem from our exam. Before I read the question I always thought that AC is more dangerous than DC because at the same voltage, AC voltage is higher as it has a peak voltage than DC. I've...

Homework Statement Hello i just have an interesting question, and was wondering if my answer to it had any validity. Ok so i did an experiment The Current balance experiment(for everyone not familiar with it, you can google it and get all the info you want) to try and estimate mu naught...

Hi guys, first post here. I am an Electrical Engineering student (2nd year) and I have a part time job doing qualification and FMEA type work on power supplies. It's been a great learning experience and it's really helped me in my classes. Right now, I am doing a qual on a low voltage dc...

I am constructing a small wind generator for a college project. I want the 0.1 V AC output of the generator to charge a battery. To do this, I need to convert the current into DC. I am familiar with things like bridge rectifier circuits, but the smallest diodes I can find have a forward "turn...

Hi sir, I am new about to this site.Actually I am an embedded engineer. Right now I am working on :smile:Pick and place robot.I want to control dc motors. I don't have any datasheet of DC motor.But I want to know how to calculate dc motors parameters required for the moments of robot.Right...

Torque has an inverse relationship with motor speed and I can understand why it's like that (more speed = more cemf = less current = less torque). On the contrary, my SCR controlled DC drive manual said that a DC drive could control a DC motor in a way that give constant torque from 0 rpm to...

Hi all, I have recently observed a very strange thing (or rather, I shall say unexpected phenomenon). When I deposited some charged micro-particles between 2 electrodes (vertical plates) with a DC bias in hexadecane oil, I expected the negatively charged particles to go to the positive...

what is meant by dc equivalent circuit and dc load line analysis? why we require these two ? advanced thanks.

Homework Statement The circuit in the figure is composed of two batteries (e1 = 8 V and e2 = 6 V) and four resistors (R1 = 110 W, R2 = 40 W, R3 = 30 W, and R4 = 50 W) as shown...

Homework Statement 1)Rank the brightness of the bulbs. 2) What happens to the brightness of the bulbs when A is unscrewed and removed. 3) A is unscrewed, what happens to current through 3,4,5. Red circles are bulbs and the black circles are reference points. The Attempt at a Solution 1) I...

I know the magnetic field makes a circle around a wire with current flowing through it. So I wondered if a motor could be made in the following way. Take a round plastic sleeve with an inner diameter slightly more than the wire. Glue 4 magnets on the sleeve, such that they form a circular...

Homework Statement Find the voltage across the capacitors in the circuit given under DC conditions.Homework Equations V=IRThe Attempt at a Solution The solution is already given (the picture attached was obtained from the solution manual. I have a difficult time understanding how they arrived...

I'm an entry-level engineer, and I have a design question for the forum: I'm designing a multiphase buck DC/DC converter which will convert roughly 65VDC to 52VDC at up to 150A. I'm using 4 phases, so inductors, etc will be designed to about 40A/phase, MOSFETS will be paralleled for less...

DC Blocking capacitor -- How does it know where ground is? Hi Everyone, A DC blocking capacitor removes any DC offset from an input signal. I've been doing this for years without thinking about it. My question is, how does it know what the local ground potential is? My only thought on...

Homework Statement The positive terminals of two batteries with emf’s of E1 and E2, respectively, are connected together. Here E2 > E1. The circuit is completed by connecting the negative terminals. If each battery has an internal resistance r, the rate with which electrical energy is...