What is Dc: Definition and 1000 Discussions

DC motor question: Do the permanent magnets make a motor more efficient as opposed to using coils for the field magnets? Are the permanent magnets responsible for half of the force in which propels the shaft? Do the magnets perform half the work and the electric the other half? Thanks so...

I recently acquired by accident a 750 watt DC to AC power inverter, designed for powering AC appliances off of a car battery or other 12V power source. I have no need for such functionality. I am really interested in high voltage projects and I was wondering if there are any interesting...

I recently acquired by accident a 750 watt DC to AC power inverter, designed for powering AC appliances off of a car battery or other 12V power source. I have no need for such functionality. I am really interested in high voltage projects and I was wondering if there are any interesting...

1. Types off commutator and their effect on current densit? [b.]2I want to ask how many types of commutators are there in a DC machine and what is their effect on current density..[\b] [b]3.i have been working on it for a long time and came to know tht there are two types Brushed...

hi i am new to this forum. i want to use a battery that will run a dc motor, dc motor will run three phase ac generator through mechanical coupling and the three phase ac generator will produce out put, now two phases of the ac generator will b utlilized by the load and 1 phase will recharge the...

I have two problems that have been bothering me, which I just cannot seem to figure out. Both have to do with current in a DC circuit with multiple resistors. The first one looks like this: 12 V 4 ohms |------:|:|-----\/\/\-----| |...

Hey guys, I am new here and had a question. I currently have a 1 V peak (2 Vpp) AC wave coming into my system and I want to find the most efficient way to convert it into DC. A simple bridge wouldn't work for me because too much of the voltage would be dropped across the diodes. The system...

Hello, I have many time thought about AC & DC Motors, but have not yet find out. Example. if a motor of 4HP 48VDC. We give it power 48VDC but 1HP power, so what happens? And what if we connect it directly with solar panels of 48VDC and 4HP power. So when sunshine is lower how it will...

A circuit has a battery(V), Capacitor(C) and Inductor(L) connected in series. At t < 0, the switch is open and the capacitor has an initial charge of -800uC and Io = 0.0Amps.. When the switch is closed at t = 0, I want to know what happens here. I only understand an LC circuit where there is...

I have heard that 'we don't get shock from dc current because it is constant but we get shock from ac current because it is alternating'.Is that true? If it is HIGH VOLTAGE DC CURRENT THEN?

DC Circuits -- Power? I have a physics question I have been working on for quite some time, but have not yet been able to figure out. I am assuming it probably has more to do with unit conversions than with actual calculations, but I am rather stuck... Here is the question: An electric clothes...

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.