What is Dc: Definition and 1000 Discussions

A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmission).

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  1. D

    RC DC Series and Parallel Circuit

    Hi! Homework Statement Homework Equations V = IR Kirchhoff Current and Voltage Law. The Attempt at a Solution I am facing difficulty with this RC circuit. I tried looking up solutions but all I could find were either exclusively series or parallel. My first guess was to take Total Current...
  2. J

    How does this kind of DC motor work?

    Homework Statement I used a similar motor to this one in a prac, and then realized that the arms either side of the coils were not magnetised. I was wondering where the magnetic field comes from, and without any special equipment is it possible to calculate it? Homework Equations t=bain
  3. W

    Inductance of DC Electromagnet Coil. Help

    I am trying to make a DC electro magnet coil. The Coil is wound up to the core. And works fine. But I'm not being able to find out the inductance of the coil. The Resistance of Coil R20= 490 ohms. Impedence is 523 Ohms. 110v give .21 amps. Please Help.
  4. S

    Using a DC power connector to power PC side panel case fans

    Hello, I was considering a small project to solve an issue with PC case fans. If you have fans on the removable side panel, the wires to power them is quite a pain to disconnect each time you want to take the panel off. I was wondering if it would be possible to take something like this...
  5. D

    Understanding the Basics of d-axis and q-axis Currents in Alternators

    A HVDC connection in a transmission network may reduce the system effective inertia due to the decoupling of mechanical and electrical systems. Could someone please tell me what does the above sentence suggest?
  6. M

    DC motors seem to have shorted rotors

    A practical DC motor armature is nothing but several "textbook DC motor" single armature windings bundled togheter and isolated together right? Like on this picture: http://content.answcdn.com/main/content/img/McGrawHill/Encyclopedia/images/CE152200FG0010.gif What really beats me though is...
  7. C

    Why use a double fed wound rotor induction generator in wind turbines?

    With large wind turbines which have AC generators why do they convert from AC to DC and then back to AC before connecting to the grid, why not just connect straight from generator to the grid without converting? Very confused please can someone explain!
  8. jegues

    H-Bridge Control of DC Motor: Battery Bank Voltage vs Motor Ratings

    If we assume we are using an H-Bridge to control the average voltage across a PMDC motor, is it still necessary that we place a buck converter between the battery bank and the H-Bridge in order to step down the voltage supplying the H-Bridge? I've attached a schematic of what I'm reffering...
  9. J

    Maxwell 3D - DC analysis on Human Body

    Hi, I am using a Human body model which I built for some simulation studies. I was trying to pass DC current through the Human body and though my Project completed the simulation successfully I got the below warning message. Can anyone please help me interpret it? The error log is as...
  10. K

    Several questions about DC electricity

    Hello, I have few questions about batteries and AC->DC adapters 1- in AC-DC converter: if I have a device required 12v and 1amp .. will it hurt the circuit if I connect 12v but more amps ? I heard it draw only required currents .. is that true ? 2- in batteries: why when we buy...
  11. T

    Charge an emergency fan on AC or DC setting?

    I've an emergency fan with an AC/DC button on it, but its manual doesn't say on which setting it should be charged. I've tried charging on both settings, and it can be charged either way. On the back of the fan it reads: "AC 220/240 50/60Hz 19w" The fan's box only says: "DC...
  12. I_am_learning

    Is conventional commutator DC motor still in use?

    I think most of them are replaced by brushless types or Induction Motor with VFD (variable frequency drive). Is there some industries where they are still preferred today?
  13. T

    Brushless DC Motor torque calculations?

    Hi there guys and girls I am new to this forum , so please have mercy. I am searching for equations to calculate the torque of a 3 phase brushless dc motor. Any info or textbooks on this maybe? Thanks Tommie Prinsloo
  14. P

    Sensing circuit for AC vs DC voltage

    Hi All, I am looking for a sensing circuit, which can sense voltage signal between AC (85-265Vac) and DC (20-28VDC). Any idea how to design this circuit? Here is the main project: - looking for power supply circuit with Single Input terminal for AC as well as DC voltages. I would like...
  15. R

    Why is AC cheaper to generate than DC?

    Hey guys! Novice physics scholar here who's studying electronics on his downtime. I have some questions concerning AC and DC. If you guys could answer them (simplistically please, I still have a lot to learn :P) I'd really appreciate it. I'm reading here that 'AC costs less to generate then...
  16. S

    Simple DC motors Current, Torque, EMF and Faraday's Law

    Ok, so I'm doing an experimental write up for an experiment on adjusting voltage on the speed of a simple DC motor, and changing the number of coils. I thought that I understood what I was saying but I've recently become a little confused with the concepts of torque vs speed specifically when...
  17. F

    Current density in a conductor at DC

    Why is there a uniform current density in a conductor at DC. It’s my understanding that generally in a conductor, a sphere for instance, in a static situation, all charge is at the surface of the conductor because it the charges repel each other. So in a cylindrical conductive wire even though...
  18. Y

    Where Do Electrons Come From in DC Generated Current?

    in DC there is a movement of electrons IE in a battery there is an excess of electrons chemically stored in one end that desire to travel to the other side of the battery where there are a shortage of electrons where do the electrons come from in a DC generated current ? if electrons do...
  19. H

    Calculate DC current through an inductor?

    Hi everyone, Say I have a series DC circuit. The circuit contains a 100V DC source, a switch, a 1.5H inductor, and a 1nF capacitor (all in series). If I close the switch for 2uS what is the current at that time? Initially I thought I could rearrange V=L*di/dt to V*Ton/L = di/dt which would...
  20. P

    Can AC devices (like heaters etc) work on DC power supply?

    Hello, Is it possible to run heating and elements and other devices with DC supply? I have turned on Nickel-Chromium Heating wires with AC but is it okay to use it with DC supply? What's the main practical difference between AC & DC, as long as the voltage and current of supply is...
  21. V

    Does electromagnetic waves are generated by dc current?

    I am beginner in physics.I have question that when dc current flow they flow with apparent drift velocity so it appears that it should not emit em waves.But in actual current flow electrons are accelerated due to applied potential and also deaccelerated during collision so even they appear to...
  22. O

    How to Derive constant of total back/counter EMF for DC motors?

    Hi, I have been reading around about back EMF and their derivations for simple DC motors. However for some reason, the step between obtaining the total emf of the motor from summing the individual emf of the coils is not very clear. For example: Induced emf due to single coil: e = d∅_c/dt...
  23. B

    Sizing a DC motor to move a weight and counterweight

    This might be a silly question for some but I was wondering how do I size a DC motor to move a weight and counter weight? Suggestions for a better design are also welcome. I want to build an enclosure with an automatic door (simple limit switches and an arduino to flip the motor on and off)...
  24. J

    Limiting DC Current for Car Battery Use

    Is there any way to take 12 volts dc from a car battery and have it go thru some components so that what comes out amounts to still 12 volts dc, but is limited to only 20 ma output? John
  25. F

    DC Power Supply to AC Gear Motor

    Hey! I am trying to figure out the best way to run a AC gear motor off a DC power supply. Any help would be greatly appreciated.
  26. E

    Optimizing DC Current Through Neodymium Magnets for Efficient Power Transfer

    Hi I want to pass DC current through a magnet, essentially using it as connector. The magnet I am using specifically is Neodymium (NdFeB) grade N42. The DC current I would like to pass through it is 100mA ~ 150mA (3V DC ~ 7V DC) I would like to know if there is any downside to the magnetic...
  27. Crazymechanic

    Are DC circuits similar to AC circuits during switch on/off?

    Hello i have a little clarification to make for myself with the help of you:) So we know that electricity moves so fast through the wires because the charge is being "pushed" by the EM force which is mediated by the photon. Now AC systems no matter what the frequency have real photons...
  28. D

    Fourier series - DC component, integration problem

    Homework Statement Find the Fourier series representation of: f(t)={-t , -∏<t<0 f(t)={0 , 0<t<∏ This is a piecewise function. T=2∏ (the period) Homework Equations a_{0}=\frac{2}{T}*\int_0^T f(t),dt The Attempt at a Solution I need help only with calculating the DC...
  29. C

    What Is the Minimum Diameter for a 600kV DC Transmission Line with 2% Loss?

    Homework Statement You have been asked to develop a cross-country DC electrical transmission line to deliver 300MW of power to a town 200km away. This design is to only have a 2% loss (98% efficiency). If the line voltage is 600kV, what is the minimum diameter that the aluminum wire can be...
  30. S

    How to avoid DC bias on output?

    I designed the BJT amplifier below. After substituting in for the values of the actual resistances measured in lab, I reran the simulation. The hand calculation I derived for the gain was nearly spot on with what I was seeing in Multisim. Now, when in lab I get approximately the same value I...
  31. J

    DC transmission lower loss on higher voltage?

    Does a DC transmission line for a given amount of power, do better at higher voltage? I know power is the product of the Voltage and current. The logic given to me by one of my peers was that I2R losses are less if the current is low. And so for a given power, it would imply V to be higher...
  32. A

    Hydraulic Jack, Automatic 12 volt DC - College Project

    Hello Frnds, I am presenting my engineering final year project. It is a 12 volt DC hydraulic jack. This jack is made to lift light motor vehicles and light commercial vehicles. Its capacity can be increased by changing some parameters. The project consists of a 12 volt DC...
  33. S

    Adding a 2V DC Bias to AC Mains

    Need to do something which requires adding a 2V DC bias to power coming out of the wall (120V, 60Hz), going to a motor. Basically need the 2V DC bias across the motor windings. Motor windings have about a 10 ohm DC resistance. I have a DC power supply that has a max voltage of about 50V...
  34. E

    DC Value Measured from Fourier series

    1. http://imgur.com/UoUb27B 2. none? 3. not really sure what this question is asking. I thought that n=1 because its the fundamental frequency and the DC value should just be 120 V. I looked at some other questions and the answers were not found using that method.
  35. R

    Supply different voltages using a dual dc supply?

    Hi all, I have - 2 ICs that requires -10v and +10v - 1 IC that requires -5v and +5v How can I power them using one dual dc supply? Thanks!
  36. L

    DC Sputtering of Silicon without Magnetron

    My question has to do with Sputtering Silicon onto a substrate using DC without a Magnetron. The system in the lab I'm at isn't currently capable of RF sputtering and the status of the magnetron is unknown. Is there any way to use a sputter with DC to deposit Silicon onto a substrate? On the...
  37. S

    Pulsing DC current through coils

    Hi, What hardware do I need to buy if I want to pulse DC power, say 12v through some regular coils with iron cores. Can I use a regular power supply connected to some other device? How would I pulse the output of the power supply?
  38. S

    DC Motors and Nameplate Ratings

    I picked up a DC variable speed treadmill motor for a project that I am working on and I am having a hard time finding the information that I need. I need to drive a secondary pulley through a range of RPM up to a specific point. In order to pick the right size pulley, I need to be able to...
  39. K

    Solid state DC circuit breaker to protect a load

    My choice of solid state Dc circuit breaker is the Mosfet, easily available( i got loads!) i want the mosfet to interrupt the circuit to protect the load from overvoltages This is what I've done so far, please help its not working the way i want it to. note to mods: i also put this...
  40. K

    Solid state DC circuit breaker, used to protect a load

    My choice of solid state Dc circuit breaker is the Mosfet, easily available( i got loads!) i want the mosfet to interrupt the circuit to protect the load from overvoltages This is what I've done so far, please help its not working the way i want it to. the resistor connected to the...
  41. A

    DC voltages, someone shoot me down please

    Hi, I am trying to double DC voltage from 3v to 6v apparently this circuit works... charge in parallel discharge in series, can somebody shoot me down and tell it won't work please? Thanks Anthony
  42. A

    Problem with constant dc supply by capacitor

    I have a problem how can i obtain a constant value of dc voltage from a capacitor(dynamo) to supply a device.. As we know if the capacitor is directly connected to the device, the voltage will drop and the device will not have enough voltage to function. what is a better way?
  43. C

    DC Motor: Wooden vs Metal frame/shaft

    In DC motor or even in AC motor, if we use wooden frame and shaft, would it be advantageous than using Metal frame and shaft? Assume that would can with stand any temperature.
  44. M

    MATLAB DC conduction equation in Matlab

    Hello I am solving DC conduction equation in Matlab. My equation is 1/r * ∂/∂r [r*σ* ∂V/∂r]=∂ρ/∂t My equation is 1D(only varies with radius) and time dependent. i am using pdepe solver.The space charge ( ρ) is the time dependent variable. But the form of MATLAB pdepe solver the time...
  45. Crazymechanic

    Efficient DC Transformer Design with Toroidal Ring and Magnetic Fluid Technology

    Hello, so I was looking at some dc to ac mechanical generators when a dc motor is used to drive a generator which in turn induced ac as was used for power conversion back in the day when semiconductor devices were not around yet.Well they had some drawbacks as the mechanical wear and etc. So I...
  46. H

    Engineering Solving DC Circuit Question | Part d Confusion

    Homework Statement http://imgur.com/9fk2QXV Homework Equations V=IR The Attempt at a Solution I am stuck on part d, i have found the answers for part c to be 12,6 and 8 for I1,I2, and I3 respectively. For part d they seem to say that I3 is just equal to I1+I2, but i am confused...
  47. T

    Equivalent Resistance (Prep for Lab on DC circuits)

    Homework Statement Use the circuit shown to answer the following questions. At time t = 0 the switch in the circuit is closed. Answer the following questions after the switch in the circuit is closed. What is the equivalent resistance of the circuit given R1 = 5 , R2 = 5 , R3 = 4 , R4 =...
  48. T

    How can i find AC frequency from DC?

    can you tell me all of the equations to find AC frequency? also, what is AC voltage? is it somehow linked to frequency?
  49. B

    Brushless DC Rotor Position Question

    Hi. I am curious about ways to sense the position of a rotor in a BLDC motor. I am familiar with hall sensors and back emf but am wondering if there are other ways to find the position of a rotor maybe more accurately. I had an idea about using a laser and a photoresistor around the...
  50. J

    How Does Inductance Affect DC Circuit Behavior?

    1. 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...
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