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. K

    Odd box that connects to alternator and produces 120 volt DC....

    First off, not an engineer, just invading your forum as no one seems to be able to answer this problem. I have an ambulance/fire marshals vehicle, a 1992 Ford E350 with 7.3 IDI diesel. Pre Powerstroke. It came with a red box in one of the compartments that has no labels or identification. It is...
  2. B

    Engineering I need help with my DC Motor Project

    Hi so I'm making a DC motor for my school project and I have no clue why it doesn't work properly. I used copper wire to make the coil (around 50 windings) and put that around a wooden axle (the windings and the coil itself are secured using tape and cable ties), I have a split ring commutator...
  3. O

    I need help with a Baldor dc motor, 15kw 240 volt ,150 volt field

    I need help with a Baldor dc motor, 15kw 240 volt armature and 150 volt field, I don't need the 15kw and so want to feed it with 150 volts to both field and armature, does anyone know the effect this will have on the motor, can I cause damage, what would be the approximate power output, I know...
  4. K

    B Simple yet effective way to reliably control the DC Motor speed?

    As a part of our physics high-school self-study, we are making a stroboscope. We have a small 5-V DC motor that powers the strobe disk. It works as expected, but, clearly, the motor makes the disk spin at a constant speed. Is there an easy, but effective and reliable way to control its speed...
  5. C

    I Why do brushed DC motors only use commutators, and not slip rings?

    Commutators always generate unwanted sparks and bad EM interference. If slip ring can replace commutator in DC motor, then electric vehicle industry will love it more than multi-phase AC induction motor.
  6. J

    Trying to analyze a half wave rectifier with inductor and DC source

    I am trying to analyze a half wave rectifier with an inductor and DC source load. I understand the circuit but I guess I do not get the math. I am reading a book and this is the circuit and equations they came up with. I understand how they got from the first equation to the second equation but...
  7. F

    B The historical war of currents in Mains Power Distribution: AC vs DC

    So, if I get it right, the basic argument goes like this: AC was preferred to DC because its voltage can be stepped up by a transformer. This limits losses while the current is transported from the production plant to the final user. The voltage is subsequently stepped down when delivered to the...
  8. P

    Is a Larger DC Motor Needed for Low Wind Speed Power Generation?

    Hello, I am not sure if this is the correct forum. I was torn between Electrical Engineering and Mechanical Engineering and I thought I would start here. I have been kicking around an idea for a DIY project and realizing I don't know enough about DC motors to find the parts I need. In this use...
  9. H

    Why am I blowing a laptop powerpack with dc water pump?

    Hi, I have a water pump rated 12v dc 2.3A. I tried using Microsoft Surface powerpack rated at 15v dc 2.5A to power it. Pump just started pulsing. I removed the water pump and checked the voltage coming out the powerpack and it was fluctuating between 0 and 15v. Thought I had a dud powerpack so...
  10. Pipsqueakalchemist

    Engineering Separately excited DC motor problem (Electrical Engineering)

    Hello, so for this question I know how to solve it but I still have a few questions. First when the question means it's rated at 20 HP and 600 V, it's referring to the source voltage and Pin correct? Also in order to solve this question, the rotation loss Prot was neglected. This was because at...
  11. Pipsqueakalchemist

    DC motors and Induction motor: What does "no load conditions" mean?

    TL;DR Summary: So I'm just confused when the question asks me to solve for the no load speed of DC motors and induction motors. Does no load condition mean that the output torque (Tout) is zero? This is what I was assuming so far for both DC and induction motor. Is no load condition the same...
  12. L

    Orbital shaker - DC servo or stepper motor

    Hi, I wish to build an orbital shaker (a bigger version of these examples: https://learn.adafruit.com/crickit-lab-shaker https://www.thingiverse.com/thing:2983846 As my aim is that it will work continuously for months around 100rpm what is preferred in aspects of heat and weight on top of...
  13. Echo43

    Resonance of a PWM DC Circuit

    I am experimenting with finding the resonant frequency of water in an attempt to disassociate the H2O bond without high voltage/current and using just tap water - no electrolytes, etc. I know how it works in classic electrolysis but that's not what I am attempting. Assume that there is a...
  14. amazingjoe

    Could you use Solar to power a DC to AC Inverter? (Description below)

    I'd like to take Solar Panel power output and use it to power an AC outlet on the ultra-cheap. I know a lot of people use Solar to connect to a purpose built inverter and also have a battery somewhere in the mix to provide a stable output but wondering if the following (using the assumptions...
  15. K

    Can a DC motor work without either a commutator or a controller?

    I am a mechanical engineer and my experience with electrical systems is almost nil. The concept of a simple DC motor explained here was quite interesting, especially the need of a commutator part: And then I checked this DIY simple DC motor here and was confused because there was no...
  16. SuperPat

    B How to Calculate Power and Torque for a 15kg Load at 15 RPM?

    Hi all I am Belgian and I have difficulty with english formulas. I'm trying to calculate the power and torque required of a motor to rotate a load. Here is the problem: I have a motor (axis up) on which is fixed a cylindrical load of 15Kg. The diameter of this load is 400mm Calculate the power...
  17. hi8192

    I getting my homemade DC motor to work (school project)

    hi everyone, i need to build a dc motor for my school project. I have used copper wire for the turns (60 turns), wood to build the structure of the armature and commutator. i have used neodymium magnets as my permanent magnets and paper clips as the brushes. I tried using a 9v battery with a...
  18. J

    Help my understanding of DC generators please

    Hello, I am currently working on a engineering project for school and have been tasked with researching the basics of electrical theory. We are building a small, portable hydroelectric generator for the purposes of charging a cell phone or other small electrical devices. I already have the motor...
  19. P

    Why is my homemade DC motor not working?

    Summary:: I have built a DC motor as a physics project, it has neodymium magnets, copper split ring commutator and insulated copper wire. It connected to a 12v power pack. There is definitely a proper current flowing because it creates sparks and the copper coil becomes hot. When I turned on...
  20. E

    Electrostatic vs DC Conduction Simulations for E-field Analysis

    Hi, I am doing e-field simulations and have came across two types; electrostatic and dc conduction. I know that electrostatic means there is no changing field so I'm just hoping for discussion on when one is more appropriate than the other and when one definitely should or should not be used.
  21. S

    Why is it important to classify circuits as series or parallel?

    The answer sheet assumes that the resistors in both circuits are in series and that we need to use the equation Req = R1+R2+R3.. to find the Req in both cases. How come the resistors are in series, when there are multiple resistors in a single row? Also, why does the following work yield the...
  22. John Mohr

    B Does a DC Cell or Battery Actually Supply Electrons?

    I have held the assumption that batteries supply electrons at the negative terminal and absorb electrons at the positive end for many years. However, after watching this video at about 3:30, it is said that batteries do not actually supply charged particles but that the battery only creates an...
  23. binis

    A Does a DC supplied superconductive coil give off radiation?

    A DC supplied superconductive electric coil must give off EM radiation according to Maxwell's law because rotation is acceleration. Does it?
  24. ARoyC

    High Pass Filter Working Principle

    A few days ago, I learned to make an AC to DC converter. One question is troubling my mind. How does a High Pass Filter Capacitor work? Going through some websites I got a sketchy idea. As the current after passing through the bridge rectifier comes to capacitor, the capacitor starts charging...
  25. Y

    Why can a capacitor be charged by a battery (DC)?

    Hello there, I'm perplexed as to why the capacitor is DC-blocking, but the battery (DC) may charge the capacitor. I'd never considered it until I recently read it in a book. I honestly have no idea what's going on. If anyone has any idea why this happens, please let me know. I've read some...
  26. G

    DC Motor Efficiency: Why Does Efficiency Plot Look Like Parabola?

    So I am doing an experiement about DC motors, and I would like to know why the efficiency plot looks like a parabola. What is the structure behind that. Thank you in advance
  27. song youngill

    Engineering How can I find DC gain via AC simulation in LTspice

    I use this netlist and simulation result came out as shown. I need to find the dc gain here and circuit diagram, but I'm not sure how. I would be very grateful if you could give me the answer.
  28. kekkeroo

    Why a transformer cannot use DC (Ampere's law)?

    A direct current in the primary winding results in a constant magnetic field going through the center of the coil. If we have a magnetic core and a second winding, why doesn't the magnetic flux going through the core result in a current in the secondary coil, as well, according to Ampere's law?
  29. I

    Is it possible to reduce back EMF in DC motors using shorting rings?

    Shorting rings (also called Faraday rings) are commonly used in loudspeakers to reduce the back emf that is induced in their voice coils. Could something similar, i.e. shorted turns of wire that are placed in the same plane as each of the windings in a DC motor, be used to reduce the back emf...
  30. I

    Analogue Circuits Question -- AC and DC currents through a coil

    Summary:: . Hi ,so am currently doing homework , and was wondering if anyone could tell me if i have done my calculations correctly ,because am not 100% sure that i have answer to those 2 questions correctly .If i have went somewhere wrong if you could tell me where and how i could fix it...
  31. V

    LED module failing due to DC motor?

    I use a 2 Relay Motor module to control Direction on a motor (linear actuator). When Relay A is active, actuator retracts. When Relay B is active, actuator extents and Led Module is activated. After some repetitions Led module fail. Cause of the fail? I believe Surge voltage, although i am not...
  32. E

    Is this the default set up of a DC motor?

    ^because in my textbook, the set up doesn't even show the direction of dot/cross at points A/D, so we won't know the direction of current. then how are we supposed to use fleming's left hand rule to determine the direction of force?
  33. Secre

    Engineering How to deal with dc source on ac circuits?

    We are tasked to solve for the steady state voltage v using superposition theorem. I start with solving with voltage source using mesh analysis and got the current flowing through the 3 ohms resistor and get the first value of the voltage which is 3.2cos(6t+126.87). Now my problem is I am...
  34. J

    Engineering Calculating the DC value of the output voltage for a full wave rectifier

    I need help with part (a)... I know that the root-mean-square voltage is the dc-equivalent voltage for an AC waveform and what my book labels "##V_{dc}## is actually the average voltage. Hence I am assuming the question is asking me to find ##V_{rms}## ... Is my assumption that the...
  35. H

    Comparing DC to AC: Is A Always Correct?

    https://www.physicsforums.com/attachments/282071 https://www.physicsforums.com/attachments/282072 If the question changes DC to AC, the correct answer would be just A right? The reason why (B) and (C) are wrong is that the current keeps changing direction and doesn't remain constant throughout...
  36. Tim86

    DC current through a resistor circuit

    Summary:: Current through a certain resistor in a mixed dc circuit. Hi, Sorry if this is the wrong forum. I'm trying to work out the current through R1.The answer I need is 2 Amp, which I have confirmed with a simulation software. I have calculated the source current as 8A, the current past...
  37. I

    DC versus AC current in a coil

    Hello, am kind of new to all the physics stuff , and kind a terrible at maths but am trying my best to be good at it one day .So i was told to answer this question When a direct current of 2A is passed through a coil, the potential difference across the coil is 20V. When an alternating current...
  38. F

    Choosing pneumatic solenoid, AC or DC

    Hi There are mixed information on these on google. I want speed(low lag) first, valves will be open and closed 1-2 minutes. Controlling them with Arduino or ESP with relays. Do I get this right? AC 220 - controlling them with Solid State Relays + Speed of Solenoid with AC is faster than DC +...
  39. greg_rack

    Current flowing through a resistor in an RRL DC circuit

    DISCLAIMER: don't answer in terms of integrals, I haven't covered those yet :) Hi guys, I'm having a few troubles understanding RRL circuits, and have a few questions for you. A "normal" RL circuit will have a current growing inversely exponentially, starting from 0 and going to ##V/R## as...
  40. narayan821

    Does DC or AC work best for charging most industrial batteries?

    I have a source of electricity that's alternating but at variable frequencies. So an asynchronous alternating current of sorts if you will. Can industrial rechargeable batteries be charged like this efficiently? Or would DC current work best? Or normal AC?
  41. Chriz3223

    Questions about DC motor drive calculations

    Hi Physics! And again, thanks for the membership! I’m about to build a robot just with some old parts I have. The main thing is the motors. I have 2 DC Motors Specs below. (It’s a MFA975D Series with gear ratio 49:1) Operation range(Voltage): 12V No load = 147RPM Nm = 1,8 Stall Torque =...
  42. X

    Engineering Find di/dt and dr/dt for a DC circuit with indepedent current source

    Dear PF, I am trying to solve practice problem 8.2. I am stuggling with part B of the question which asks us to find diL(0+)/dt, dvC(0+)/dt and dvR(0+)/dt. My attempt can be seen below. Before t=0 the 4A current source is not present and thus it is an open circuit. A capacitor acts as an open...
  43. Wrichik Basu

    Creating a stable 5V DC supply out of 6 V (RMS) AC

    I need to create a 5 V stable DC supply out of 6 V AC from a transformer. By "stable", I mean that I do not want the ripples in the voltage that one gets from the output of a full-wave bridge rectifier. I have to feed this to two ATmega 8A μCs. I am going to create the following circuit: 6 V...
  44. T

    A question about an electron’s movement in a DC circuit

    I have been thinking of the nature of the electric current , or the motion of electrons in a copper cable of a closed DC circuit. Recently I learned the speed of electron is very slow in the copper cable and in a AC circuit the FREE ELECTRONS are in fact moving back and forth. But in a DC...
  45. F

    Engineering Continuous and discontinuous modes of series excited DC motors

    Here's my attempt: clc; clear all; Ra=1.8; La=150*10^(-3); Ls=150*10^(-3); Rs=1.8; Rt=Rs+Ra; ws=100*pi; c=1.25; vrms=240; vm=240*sqrt(2); f=50; T=1:0.5:50; for a=0:pi/9:pi/3 vt=(2*vm*cos(a))/pi wc=((ws*(Ls+La)/tan(a))-Rs-Ra)/c; x=[wc; a+pi]; Tc=c*(2*vm*cos(a)/(pi*(c*wc+Ra+Rs)))^2; for...
  46. HelloCthulhu

    DC 20kV flyback converter schematic in multisim

    I found this schematic while watching the following video on building a DC 20kv power supply: I wanted to test the circuit in multisim, but I'm having trouble finishing it. None of the transformers available look like the one used in this schematic. Below are the transformers available on...
  47. H

    Calculating Required Torque for 12V DC Motor

    I am designing a reciprocating saw that I plan to use a scotch-yoke mechanism to convert rotational kinetic energy into linear kinetic energy. I want to spec out a motor and the final thing I need to calculate is the required torque. The motor must be 12 Volts and I need to know the required...
  48. J

    Troubleshooting DC PSU Weirdness: Wall Power Issues and Potential Hazards

    [warning: wall power issues ahead] I had a friend send me an LED strip with a USA wall ac to 12v dc PSU, so I slapped a 3-pin wall cable on it and spliced a toggle button into it. Everything works fine buuuut... If I put my finger here (assuming it's a resistor?) I get some current, like so...
  49. L

    What is the best DC motor for spinning a vortex impeller at 3000 rpm?

    I am looking for a recommendation on the proper DC motor to purchase for a custom project. My project involves vortexing water using an impeller, which resides in a 1.5" OD stainless shaft residing in sealed bearings - not a whole lot of resistance, easily turned by hand. I need to spin this...
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