What is Dc: Definition and 1000 Discussions

Homework Statement Need to establish a Thevenin equivalent for the circuit attached. Homework Equations None given. Need to use Kirchhoff. The Attempt at a Solution I worked out the following: I said that R3 and R4 are in series as there is no current splitting because 0A...

As the tittle, I am looking for off line switching supply of about 400VDC output. Anyone know who make this? Thanks Alan

Hello everyone, I found on this website http://spiff.rit.edu/classes/phys213/lectures/lenz/lenz_long.html a very good explanation for AC generators. Particularly I am considering these two images: And I found those equations and graphs are quite interesting and wish to make a...

Hello Mates, I m making my project on Wireless robotic arm using microcontroller. I need DC Geared Motor with following specifications: 1) low RPM. 2) High Starting torque. 3) High Holding torque. Can any1 please help me in selecting motor ??

I understand AC is economic for transportation and easy to produce from converting mechanical energy into electrical energy. However, why don't electronics turn on and off because of this alternating nature of the current? For light bulb, maybe it does turn on and off and our eyes don't have...

Hello, I would like to know if the motor efficiency is changing with respect to applied voltage or it doesn't change. What I do mean. The efficiency=(V*I)/(Torque*velocity) and the power losses= I^2*R. Can I say that mechanical power ( Torque*speed)=V*I-I^2*R If so, can I say that the...

Hello world. Is there any way to convert mechanical energy into DC electricity energy WITHOUT using any magnets ? I know there is homopolar generator but it uses magnet and as I said I need something that doesn't use any magnets. I also know there are stuff that use friction (triboelectric...

Hello all, I have a few questions about calculating efficiency, torque and horsepower for a small pulse dc motor. The only parameters that I have are input voltage = 39Vdc, input current = 2A and rpm = 90,000 rpm. Are the above values obtainable with the given information? This is not a...

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 resistor after...

I'm building a wire strippers by cutting a hole in a piece of 2x4 which has a blade on the bottom of the hole. I want to use a motor to pull the wire threw by using a motor a gear and a strip of metal. The strip of metal clamps the wire down on the gear which is turned by the motor. I was...

The torque that is generated inside a magnetic motor is caused from the magnetic forces that is this formula: F = ILB F: Magnetic force(Not sure what the unit would be...) I: Current(A) L: Torque(N.m) B: Magnetic field.( Gauss or Tesla?) I just need some help in calculating the total magnetic...

What type of digital signaling is more efficient, digital DC or digital AC? With digital DC, the square-wave signal is only between a (+) value and 0. With digital AC, the square-wave signal is between a (+) & (-) value.

Hi everyone, I need a suitable power supply that runs off 240VAC (a regular mains socket found at home) to power two DC motors in parallel. The motors are each rated at 24V, and have a full load current rating of 15A. I've performed a search, but the power supplies I've found are either...

Hi everyone, I have a 24V, 15A D.C motor, and need to control its RPM. I know RPM is directly proportional to voltage, and so the answer lies in a technique to vary the voltage across the motor. I have looked into potentiometers, variable resistors, and pulse-width-modulation, but since I...

Hi all, I came across this forum and feel as though someone can point me in the right direction. I am looking for a 12v DC motor to power a turntable, I have a speed controller to slow the motor down. I need to know if there is a DC motor available to buy which can't be turned by hand, a...

I am a mechanical engineer and I'm working on a project in which I need to generate a large magnetic field in a coil of wire. The current system uses AC power (480V or 230V) and I am exploring the possibility of using a DC battery source. The coil is has an OD of 72mm, an ID of 62mm and a...

Homework Statement Consider the circuit shown below. A Q-point value for IC between a minimum of 4 mA and a maximum of 5 mA is required. Assume constant resistor values, and suppose that b ranges from 100 to 300. It is desired that RB have the largest possible value while meeting the other...

DC motor rotor + stator : torque by attraction ? [Solved] So on that image there's a very simple dc motor. Knowing that F = B*I, the force acting on the wire can be represented as on the image. Also the current passing through the rotor will create a magnetic field, represented by Brotor...

Hi everyone, As part of a project, I need to rotate a horizontal solid aluminium cylinder of approximately 15kg mass, 15cm radius and 8cm height such that its surface speed is a constant 160km/h. I need a D.C motor capable of achieving this. The acceleration of the wheel does not matter much...

[Confuse!]Capacitor and resistor in DC circuit, please help :) Homework Statement The figure in attached file below shows a circuit in which a battery (electromotive force = 10V) is connected with three capacitors (capacitance = 1 microFarad, 2microFarad,3microFarad) and two resistors...

Can someone explain me why dc motor is self starting differ of ac who is not self starting motor?

I recently bought this resistor: http://www.radioshack.com/product/index.jsp?productId=12573233 I want to hook it up to about 50V DC, but I want to know if this would be harmful to the resistor. According to the description it can handle up to 800V, but its power rating is only 25W. This...

I currently have available a 12V DC source and from that I want to power 3 LED strips but I want to be able to either have them all on at the same time, blink the strips in a pattern, or have them off. I have done some research into 555 timers but it looks like they won't be able to handle the...

I'm doing the solar system design now . so far seem like everything is on track, but now i face a problem on the DC cable loss. is that has any formula to calculate the dc cable loss, i has using this formula is (losses of the cable (Ω/km)x length X current produce by the solar panel...

Homework Statement when running at its rated load, a 40kW series motor takes 74A and 550V. The rated speed is 750 rev/min. the armature and field resistances are 0.35 Ω and 0.15 Ω respectivly. when the load torque is doubled the rated value, the current is 110A. dertermin the moror speed and...

I do not work with this type of conversion so I am not familiar on how to understand so here is my problem I have a electrical supply line putting out DC current at .6 amps by 17 volts which equals 10.2 watts here is my question if I take a 125 volt AC bulb rated 10 watts will this be enough...

As we know the contactor in power circuit make spark when it open and so its contacts may damage and aging Is it possible to replaace the contactor by power electronics switches such as MOSFET TRIAC and IGBT? Any help will be appreciated

hi guys homework r u? I have zis question about locomotives Is it possible to drive locomotive by brushless dc traction motor?

Hi All, i have seen the following parameter in FET data sheet in the maximum ratings column DC drain current, Pulsed. What does this parameter represent? In my design how should I take care of this? Could someone please explain me this? Thanks in advance, Regards, Satya

Hello... The concept that resistance can be for a dc supply only and not for the ac supply coupled or superimposed to the same circuit, is something i don't understand to this moment... I first realized this in diode systems... where i saw bulk resistance for DC and dynamic resistance for AC...

OK, I'm designing an Open Source Kite Ring Generator. See kitepowercoop.org for details. I have designed a system which uses a large inflated torus with kites attached radially around the axis on which it spins. I believe that removing the inside hub of a standard wind turbine by working in...

we have an air comprissor screw type driven by dc serise motor direct start it use in locomotive the control circut inclode pressure switch and tempratue switch but alway we have problem in it many times the motor burnt. The motor is from simo company Rated volt 110 Rated current 210...

I am building a human lift for a vehicle. I am looking a for DC motor able to life 900 ft-lbs with a brake and the shaft is splined. Sending me a link to a company that sells this type of motor would be great. Thank you, Kevin

I came across an equation for the Speed ω in Radians/seconds of a Cumulative Compound DC motor. ω= K(Vt-IA[RA+RF)/(\PhiP+\PhiS) How would we calculate K in this equation? Shouldn't the Terminal Voltage Vt be replaced by Armature Voltage Ea? I came across a lot of varying torque speed...

Hi, I know that existence of AC and DC currents but what exactly the same with AC and DC potential difference. Of-course it was very basic question and i apologize if it annoys any. Please explain the difference only in terms of voltage. Thank you.

Kind of a silly question, maybe, but just confirming... If I want the motor at S1 to rotate to one side, and at S2 to rotate to the other side... I just do that? http://img651.imageshack.us/img651/4167/motorfp.jpg

During current flow , electrons are certainly being accelerated and decelerated betweeen two successive collisions with the metal lattice. Since accelerated charge generates EM waves , why doesn't a DC current emit EMR?

Hi All, I'm trying to visualize the flow of electrons in an AC circuit. DC is pretty simple as I can imagine the electron moving from point A to B. AC on the other hand confuses me. If there's a constant switch of polarity one would imagine that the electron would move forward as the...

I read that capacitors that are part of DC circuits have a reactance that is essentially infinite. When I look at equations, this seems to make sense: If the reactance X=1/ωC, ω is zero in a dc circuit and so this means that X approaches a very large value. Thus, if you use V=IX, this means...

If I have a constant emf, then connect it to a resistor and an inductor and capacitor in parallel. At the time when the switch is closed (I haven't drawn it), the voltage across L and across C should be the same since they are in parallel(?) (in fact it should be in any time later) But...

hello world. i am interested in a simple inverter circuit that would also be easily adjustable, i.e. frequency, amplitude. but i want to build using most general discrete circuit elements. NO integrated circuits NO comparators NO etc... just inductor, capacitor, resistor, DC supply ( any volt...

Homework Statement The resistance of the armature windings of a DC motor is 5Ω. The motor is connected to a 120V line. When the motor is spinning at full speed, it draws a current of 4A. The back EMF at full speed is: Homework Equations Pav=\frac{1}{2}I2peakR Pav=\frac{1}{2}εpeakIpeak...

I have been going through the ac signals coupled by a capacitor to a dc network.. Using superposition principle.. for solution it was shown that both bulk resistance and dynamic resistances for the diodes used are required... Why is this happening.. Since to what i know bulk resistance is...

questions concerning about the brushless dc motor in a brushless dc motor,does the power given by a battery move in and out throughout the electric current of the magnetic wire? I have the magnetic wires both parallel to each other and placed at the negative and positive terminal of the...

AC vs DC! The intent of this post is mostly for aspiring students: When working with one of my students recently….I notice he tends to freak out between the difference of AC and DC……Like they are two completely different subjects. He says one has a frequency and the other doesn’t. I say not...

I have uploaded the journals which related to the brushless dc motor. I encountered the problems as i don't know how to simulate the voltage source inverter of the Brushless dc motor system (the generation of inverter line to line voltages) and the hysteresis current block. i really need help...

Howdy, I'm using the opa2350 op amp to amplify a <1mV signal by 2000. The problem is I want to have a greater gain (either second stage or larger feedback resistor) however the DC level is reaching too high so that it reaches over 2 V, and I need it under 2 V in order for a digital read into an...

Hi guys,if i mount a dc motor on a glider that slides in 2 directions without friction, AND, instead of having it drive a mechanism, have a circular plate with an eccentrically drilled hole in it (not centre) mounted on the motor shaft though this hole, i should observe the glider sliding back...

Hi my name is Rami am from Syria and is my first post here, I'm studying communication engineering and I'm working on a junior project about ( car mirror with memory ) that saves the locations of a car mirror for many drivers .. i'm using Atmega-16 to do this with keypad and L293 Motor Driver...

I wish I had a plot of voltage on the X-axis and danger level on the Y-axis for AC and DC. I was talking to an engineer at work, he was telling me that DC is more dangerous at high voltage. I said I disagreed with him but did not do into detail as to why I thought so. I did say that I've...