Dc Definition and 1000 Threads

Homework Statement I need to find the DC and high frequency (HF) gain of this filter: http://www.flickr.com/photos/96575810@N00/4420162040/ (The url is [PLAIN][PLAIN]http://www.flickr.com/photos/96575810@N00/4420162040/ in case that doesn't work) Homework Equations The book defines...

In a DC circuit charges flow in the opposite direction to the electric field. Is the difference in potential energy over two points b and a of a point charge due to the source charge of this field defined as voltage?

Sorry for this noob idea but I'd like to know what happens if: A 2 HP DC electric motor is coupled to a 5kW DC Generator, will the 5kW DC Generator produce a 5kW output? What will happen to these two equipment. Thanks for the Reply!

Hi experts, is it possible to have a simple 2-directional switch using just 2 12v coil relays (having normally opened and closed contacts)? Is this equivalent to a h-bridge or must a h-bridge be used? The triggering is from a 555 to the relay coils. I tested my circuit but it does not seem...

Can someone help me solve this problem using matrices and not Kirchhoff's rules. My professor posted this as a challenge question and I would like to know how to solve such a problem. Please help! I tried looking up how to solve this type of problem using matrices but to no luck. I don't...

Hi Experts,o:) I am trying to reverse the direction of a spinning dc motor (around 30watts) but not sure how this should be done. I have a logic for the switching of the power polarity to the motor but am worried if back emf would be an issue when the motor is spinning and the polarity...

Hi my name is Bruno ! I don't really know about circuit board hardware ect ect But i have a pretty good knowledge about Dc and Ac , relay , ohm law ect ect ! And I am learning fast ! There is my problem ! I have a Bmw Convertible with a soft top controlled by an electronic box that...

I am a student trying to learn about PLCs. I was buying a light (beacon) to install on my PLC and had a question about the output voltage. On the PLC I saw that the outputs are 24 V DC. On the beacon I am ordering, the options are: 12V AC/DC Full Voltage 24V AC/DC Full Voltage 120V AC...

i am unable to understand dc motor commutation can anybody help please

I have a standard AC-DC rectifier that gives me +24V, 12.5A power supply. Now, I've a problem... what's the simplest way to generate a negative voltage between the rails? This may sound silly but I really thought I could just use the power supply as I would do to generate a positive voltage...

Usually all of us observe thundering light at rainy day. A light is produced. Is that a.c or d.c Thanks

What effect does a DC magnetic field probe have when submerged in salt water ? i.e. There is not an electrode..just a plastic insulator with calcium ions pulsing through it giving off a magnetic pulse submerged in salt water. Sodium ions are paramagnetic, so would these be attracted to the...

I understand pretty much everything related to this, except how many currents should I put when arbitrarly putting them. The number of resistors? The number of wires? The number of loops? I'm seriously lost here, thanks!

I'm trying to modify a VCR so that the big drum that scans the tape spins slower (for an art project...). It's a brushless DC motor that uses a special VCR-specific IC to control it, I believe. The chip is a sanyo LB11885 (http://www.semiconductor-sanyo.com/ds_e/EN7884A_d.pdf" datasheet). VCR...

Homework Statement Determine the magnitudes and directions of the currents through R1 and R2 in Fig. 19-47, where R1 = 37 and R2 = 16 . Figure 19-47 (image attached) V1 = 9.0 V V3 = 6.0 V R1 = 37 \Omega R2 = 16 \Omega Homework Equations V = IR The Attempt at a Solution...

hi i want to drive led's through a RC series (time constant) circuit, which is powered by a DC source and when the capacitor is fully charged,, the switches should be such that the capacitor will discharge automatically glowing the led's from opposite direction, So the led's will give one...

hello Capacitors are widely used in electronic circuits to block the flow of direct current while allowing alternating current to pass,how it does the job? samieee

Hello, I'm very new to designing and building electronics involving anything outside of simple Transistors, resistors, capacitors, and diodes. I have a fair amount of experience with the parts previously listed and they may be the only parts I need for the task I am currently requested aid in...

Question: Assume that a 12V permanent magnet DC motor is to be used for moving the robot legs. It has a stall current of 2 ampere and a no load speed of 3000 r.p.m. Assumer that the friction at no load spped was so little that it can be neglected . When the suply is at 11V, the motor is...

Homework Statement The fastest, most powerful Class III battery charger available is supposed to recharge 8.8 kWh into a Chevy Volt battery pack in 15 minutes. What is the most likely combination of DC volts and amps to do this and why? Homework Equations W=VxI (I = amps) a 120 V unit...

Hi, This isn't so much of a home work problem just a request for clarification from those that are more intelligent than I. I actually just wrote the final for Basic Circuit Analysis and there was a question that left me totally stumped. I've attached a VERY crude, much less complicated...

Basic question here: I have a simple circuit consisting of a 12 vdc battery, a level switch and a water pump. The switch is rated for 1/4 HP @ 32 vdc, and the pump is 12 vdc rated at 15.5A. If 1/4 HP = 185 watts, I assume that equals 5.8A @ 32 vdc, and is not capable of handling the motor...

So in a DC current we have a relative uniform movement of electrons in one direction. If we would have a very narrow coil around the dc current carrying wire, (like an atom wide), every time an electron pass trough the plan of the coil, should induce a voltage in the coil, so theoretically we...

how dc shunt motors are different from the simple dc motors and is there any relation between between generators

Ok so i received the suggestion to get such a power supply by rigging a variac to a bridge rectifier, but variacs are rather expensive, so after some snooping around i came around this site: http://www.scribd.com/doc/9779212/ebook-free-energy-50000-vdc-power-supply they basically just use...

why are laminated rotor cores used in dc machines (with dc current in the rotor) when there is no possibility of eddy current (or is there?).

Dear friends, I would like to know how can I remove an AC signal from a signal which is combination of AC+DC. AC signal 60V/50Hz DC=50V. Please suggest me a C code or any algoritham or a filter which can remove AC signal completely and I should be able to see only DC...

DC doesn't cause electromagnetism? That is what our teacher says. Can anyone explain why it doesn't? As far I remember I made an electromagnet from a nail by passing current through it from a battery cell about 6 years ago.

Homework Statement What direct current will produce the same amount of thermal energy, in a particular resistor, as an alternating current that has a maximum value of 2.60 A? Homework Equations The Attempt at a Solution A DC would dissipate a constant amount of thermal energy in a...

Hi, I am a 24/7 carer for my wife who has Huntingtons disease. This has caused her to loose the ability to hold a cup. I want to devise a swinging arm with a cup attatched to one end. It will be operated electricaly with a small LEGO motor that has been geared to give plenty of torque...

Hi, Can anyone help me to figure how to get 12V for the dc motor using 24V supply. I would like to use a 12V supply but that would mean some changes to the wiring. Instead of rewiring,I would like to just make do with the 24V supply. I will need a series resistor (ranging from 1k -...

Homework Statement Find a) the potential difference between points a and b b) the current of the 20 ohm resistor I drew the diagram in MS Paint. Should be good enough. http://img188.imageshack.us/img188/6515/circuitf.jpg 2. The attempt at a solution I just don't know where to start...

Hello Forum, I have a 3 phases DC brushless motor from a Hard Disk Drive, when energize one coil and turning by hand the rotor i can feel 4 steps per rotation, is this means that this motor has 4 poles of north and south? Thank you in advance, Anita

I am a ecologist and I have been playing around with a water conductivity sensor, however in seawater there is the obvious oxidation issue. I have found that with the right correction factors and with the polarity frequently reversed, the electrodes have reasonable accuracy. The Question: Is...

[b]1. Eight lights are connected in parallel to a 119V source by two leads of total resistance 2.5 ohms. If 240mA flows through each bulb what is the resistance of each? What fraction of the total power is wasted in the leads? [b]2. V=IR, P=I^2(R) [b]3. V=.24(119)=495.83/8=62ohms...

Dear Sirs/Mdms, I would like to find out how different is a brushed vs brushless dc motor in terms of size, weight and power . I can find articles on the net regarding some comparisons between the 2 types. For example, a brushed is less efficient than a brushless motor. But i cannot...

ELEG -- DC Motor Control Systems Problem Homework Statement The voltage equation of a dc motor is written: ea(t)= Ra*ia(t) + La*[dia(t)/dt] + Kb*wm(t) where ea(t) is the applied voltage; ia(t) is the armature current; Ra is the armature resistance; La is the armature inductance; Kb is...

I recently started doing research to build one of these (popular?) two-wheeled balancing things. (A segway clone) I don't know how to calculate the proper size motors (a pair of motors) for this. I know you have to consider the torque and rotational speed required to size the motor. Desired...

Can a DC choke (inductor) filter be used in a resonant circuit with a capacitor? If connected in series with a capacitor will the two resonate, or will the signal passed be half wave? I thought all inductors can be interchangeable but some have certain applications such as DC applications.

When a DC flows through a wire, does the electric field vary? If a changing electric flux produces a magnetic field, then electric field will have to vary constantly, right? If that's not the case, then what produces a magnetic field around a conductor carrying current?

Hi Everyone, This thread is a modified continuation of my "Digital Voltage Meter circuit " thread I started a long time ago here: https://www.physicsforums.com/showthread.php?t=180822 But with a few changes. In this case, I have a large DC capacitor that I want to monitor the voltage...

Hi I need help deciding how to design my DC motor. I know about series wound and shunt wound motors. I want to design a motor for the highest speed at no load. The limitations are 12V and 1A. I can only use copper wire (0.315mm, 0.2212 Ohm/meter) and shimstock for the electromagnet...

I want to know if I am figuring correctly. I am putting together a 12 volt 3 amp DC power supply. The formula in the instructions is C = Tc / R. I figured the required cap to be 20,750 uf. When I went to a couple of supply catalogs to check the price for the cap I found that no one had had a...

Hey all, i have a summary report coming up which is assessed. I was just wondering if u guys could help out on the know how, terms and all the other stuff to go along with that stuff. Apparently the Summary has a 'prac' layed out like a case study i guess. The teacher said that we would need to...

Hi fellow thinkers. I need constuctive criticism on the following:- Imagine a tube circling around into a closed loop - like a hoop. Inside the hoop is a ring of connected bar magnets all facing the same way. Pressurized steam is fed into the hoop - and exited in such a way as to spin the...

Hello! Lastly i was designing a toy car moving in both direction foward and backward using relays and switches. I thank everybody who helped me. Now i want to move to h-bridge. i have read many books about the h-bridge but one problem that i still have is how to chose power FET transistors...

I realize that this may be an unlearned question. Is switching DC current, on and off, let's say 60x/sec, similar or exactly the same as AC. From a laymans point of view it is not. I may stand to be corrected but, AC indicates that the current flows, or is switched to flow, in opposite...

Ok so for those of you who have followed my recent threads, you will know that i am trying to find practical ways of obtaining a 16 kA DC pulse to create a magnetizing field. I have tried to locate a strong spot welder, but the DC pulse is three phase and results in a non uniform magnetic field...

Hi, Question 1: can anyone tell me do we need a rheostat or face-plate starter for a 12V dc motor? I read in the book and it says the starting current for the motor is very high and it might burn out the armature. I was wondering if I could just directly connect the 12V supply to the...

I am trying to adjust the output voltage of my 12v DC adapter. Is it possible to wrap the wires of the adapter around a toroid in a closed circuit, and then wrap another wire around the toroid to have the output voltage of this wire decreased, and the current increased? Example...