What is Dc: Definition and 1000 Discussions

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...

Hey all, I have a small question that's been bugging me and I can't find an answer anywhere. How do you test the resistance of a DC motor? My main "practical" idea is to test it as you'd test any other piece of metal: connect a power supply, an ammeter and a dc motor in series, and connect a...

Homework Statement A meter is shunted by a parallel resistance. a) Determine the required value of the shunt resistance if the maximum value of the current I, is 200A. The meter can read a maximum of 1 mA and has a resistance of 0.1 Ω. b) If the shunt is made of copper and has a...

Which can induce more current in a conductor, a DC current of 50V 10A or a step change from 1mA to 3mA? I thought that in a DC circuit the inductor would not induce a voltage as V=L(δI/δt) where (δI/δt) is 0 for a DC circuit. But then some websites that I have looked at say differently so I'm...

I still don't understand why these types of motors tend to spin in one direction or another. In theory the direction of spin should be random since when the north pole of the rotor magnet is lined up with the north pole of the electromagnet in the stator the rotor could be repelled clockwise or...

Hey everyone, I am trying to solve for the circuit that I have attached. So I know that for a opamp, it does not draw any currents into its input side and the nodes b and c are the same potential. To figure out the potential at node b, i need to know I_6, but that 6k resistor is messing...

Hi guys, I have built a simulation model for a permanent magnet DC motor, but I am having trouble accepting the results. dynamic equation states. machine accelerates as long as there is torque imbalance between elctrical and load torque, below. dw/dt = (1/J)*(Telectrical - Tload - Tfriction)...

Homework Statement Let's say i have a circuit with two resistors connected in parallel with some source. Then another resistor is added in parallel with the first two so what happen to the current in the battery? Homework Equations The Attempt at a Solution Should the current in...

When I put a current into a dc motor, there will be a turning effect. But I thought as this happens, won't there the an induced current that flows in the opposite direction? Bt Fleming's Right hand rule, the current will flow in the other direction. So I'm quite confused about this...

Hello! I'm a long time reader, but this is the first time I've not been able to find the information I've needed already... I have a small electromagnet that needs to have an AC current (it is essential that the electromagnet has a reversing polarity) but the source of power comes from a 6v...

Hi anyone I have 7 small 12v dc motors RF-500 TB, max efficiency 0.08 amp max speed 2180 rpm. These motors are just holding plastic reflectors of an american police car's roof barlight, they are individually fitted in separate pods with their own 50 watt bulbs. I need 5 pods to spin slower...

My dad is an electrical engineer, I am not. I am just a dumb race car driver. That said, I want to not ask him too much about all this stuff since I want to not look like a complete idiot. I feel that some of this stuff should be somewhat common knowledge, but alas, I am drawing a blank. I...

Hi, I'm comparing two electrical appliances, one with a DC motor and the other with an AC motor. The AC appliance has 250 watts. The DC appliance has 0.6 amps and 120 volts, and its wattage is 72. Given these specs, I would like to know which appliance would have a more powerful motor? In...

This is from wikipedia's article about Variable-Frequency Drive Controller: Variable frequency drive controllers are solid state electronic power conversion devices. The usual design first converts AC input power to DC intermediate power using a rectifier or converter bridge. The rectifier...

what does torque of 5 kg.cm meant by for a dc geared motor? can I give a load upto 5 kg for that motor? If so what are the conditions? Is torque related to RPM?

I read about 1/f noise. It says it is inversely proportional to frequency. What would happen at zero frequency or dc? Will it go to infinity? But when we measure some dc value we don't find any infinite voltage which clearly disproves this equation. What is the reason behind this? Thanks in...

I am making a functional model friction crane. I am in the design and material gathering phase right now, but I have a question about DC Motors and how they would behave in a certain situation. I plan on having a DC motor spinning a shaft with a clutch on it. When the clutch is engaged...

So in my SKIL course, (SKIL is the name of the lab courses (1 through 6) physics majors take. This course is about non-linear circuits) we need to develop some type of project that incorporates what we learn in the labs. The course deals with.. -Operation Amplifiers (Op Amp's) -Diodes -BJT...

I need help on alternative motor that I can use for vacuum that can run continuously for 20 hours a day and it should be 12VDC powered. Basically I am doing a heat exhaust system for a data center. I want to use small pipes so it won't be bulky about 1.5" and for that to work I think strong...

Hello all! First post! I've built a 7.83 Hertz sine wave oscillator that is fed into a 1,000 wind coil (soft iron rod/bifilar windings/self cancelling) and have tested in out on my oscilliscope and it's working beautifully with a peak voltage of 5.8 VAC (4.1 RMS AC). This device is being...

I am going to put a digital panel meter on my boat to measure the battery volts and a few other things. For this, I need a DC power supply for the meter with a negative which is below the boat ground. I could easily use a 9V battery and a push button to keep it on just for taking readings...

Homework Statement The circuit has identical bulbs and an ideal battery. When bulb D is unscrewed from its socket (the socket remains in its place), what would happen to the brightness of bulb F? Homework Equations V = IR The Attempt at a Solution Since bulb D is unscrewed from it...

Need help in controlling the speed of DC Motor ?? Can anyone of genius mind here tell me how to control the speed of dc motor in four quadrant operation automatically without using microcontroller or PLC ?? I Want to do a mini-project where i want to setup a speed from a keyboard input so...

I have to calculate the RMS and average voltage of a sine wave with a DC offset. I have a peak to peak voltage of 11V and an offset which is -6V. I have the average voltage as -6V and RMS voltage as 7.15V. I calculated the RMS as follows: AC Vrms = 5.5/sqrt(2) = 3.89V Vrms = sqrt(3.89^2 +...

Hi,i really need help on how to design a dual channel DC power supply that fulfills the following specifications : 1) Operation - User selection between independent adjustment for positive and negative output voltage, and series tracking mode (slave channel tracks the master channel) 2)...

Given the scenario that there is only 1 DC voltage source is there a way/ circuitry that can increase the current. I know using a low resistor could induce a higher current in the circuit, but here is the trick, the resistance is fixed. Anyone who know how to do it, please do shed some light on...

Hello, I have a question about how to analyze the CMOS inverter (this circuit: http://www.cs.umass.edu/~weems/CmpSci635A/Lecture2/image10.gif ). Just to clarify, the input voltage is connected to both gates, and the PMOS on top has its source connected to Vdd. The NMOS on the bottom has its...

Homework Statement Hi, I am trying to use pspice student to work out a ideal opamp. This is what i did: Homework Equations I have find out the gain for my opamp using simulation. But the problem is how can i find out the DC open loop gain using this software? i have google it and it just...

Homework Statement Breakdown, and find the total resistance for this circuit. Homework Equations V=IR Parallel Circuits - 1/Rtot = 1/R1 + 1/R2 ... Series Circuits - Rtot = R1 + R2 The Attempt at a Solution http://img696.imageshack.us/img696/4176/centralkootenayj2011122.jpg...

Why DC is said to be more dangerous than AC?? For example, consider a 230V DC and 230V AC.., it is said DC voltage is highly dangerous than AC.., Why is it said so?? how much quantity of AC and DC can our body bear and remain harmless??:confused:

Hello, I am rewinding the armature for a burned up winch motor. This tutorial ( http://scootersupport.com/motorrewind.htm ) shows basically the exact same motor (but for scooters). The picture shows the armature. My question is, please help me to understand- each coil around the armature...

Hi every body I've some question that need to be answered WHy DC high voltage test devices always generate negative voltage rather than positive voltage I hope that i can get an answer Thanks

Hello, I'm trying to design a boost converter, Vin =9V, Vout = 30V. I've read several publications about it and I've noticed that some of them ask one to specify the peak inductor current, diode voltage drop etc..how do I know the peak inductor current if I don't yet know the value of the...

how to design dc to ac inverter

Hi I have what seems to be a untractable problem On a racing motorcycle I am using a total loss ingition/datalogging and water pump system. To power this I am using a 5000Ma 30C LiPo battery (used because of it light weight and small size). The measured battery output is 15.2 Volts. Both the...

Having been asked to identify two methods of starting a DC motor from rest, I am struggling to get anything on the internet apart from Rheostats. Does anyone know of another technique that can be adopted for DC motor start-up? no equations required Knowing that the aramture...

I am a hobbyist, and I am not too familiar on to how to run motors. Can someone help me design a simple circuit that drives a dc motor on pulley drive of a conveyor belt. I only need a steady speed, I am not changing speeds. The conveyor belt has to stay on for 5 seconds after a switch is turned...

Hello, I have designed a water turbine which weighs about 5.3 Kgs and it rotates at about 150 rpm from a head of 3 mtrs. The water is guided by a single 25.4 mm dia pvc pipe. I can achieve better rpm upto 200 rpm by increasing the flow. My plan is to generate steady 12 Volts DC for rural...

okay so I am just slightly confused about current and about how it is drawn from a power supply, so say we have a device that requires 5 volts and uses a max of 550 milliamps, and now let's say that the power supply used is rated at 5 volts, but 32 amps, does this mean that the power supply...

Hey guys, I got this problem. I have 9 fans motors in which i need to send a range of dc signal of 0-10 volts to each one. I had decided to buy a simple signal generator that can do the trick but soon realized that having one signal generator hook up to 9 motors at the same time will not be...

I have a dc motor geared to a diaphragm pump, and all hardware are unchanged. As i increase the supplied voltage, rpm increases, but so does the current (torque). I thought rpm increase would lead to higher back emf, and thus lowers the current. So would the only reason for my increased...

I just bout some wireless controlled wireless outlets. Theses are what I bought: http://www.menards.com/main/electrical/safety-security/timers/indoor-wireless-remote-outlets-3-pack/p-1477247.htm I want change how they draw power and the functionality. I am new to circuits and have a novice...

What should be value of PTC/ Resistance to raise its temperature to 150 deg Celsius for 220V AC and 24V DC.. Please explain this with required formula...

If I wanted to create a hand crank to spin this dc motor... I want to create a handcrank to spin a DC motor at 24000 rpm. The DC motor is an 18V hobby motor from radioshack. Is this possible?

I had a 24V DC tractor cab heater that decided to let the magic smoke out shortly after hooking it up for this winter season.So,I checked the company website-DC Thermal-and they have the new improved models which claim to output almost 3 times the heat in BTU's.These are quartz type heaters.My...

i would like to design a solar assisted driving mechanism for my bicycle? What is the compatible battery specifications to power 24v 1hp dc motor and the necessary solar panel specification to charge the battery? I'm kinda clueless in this so any help would be deeply appreciated. Thanks

Homework Statement Calculate the value of the current through the 12V battery shown in figure (attached). Homework Equations V = IR I1 = I2 + I3 The Attempt at a Solution I've calculated the current for the left hand loop, see below: Loop 1: E_1- E_2- V_1- V_2=0 E_1- E_2=...

I'm building an AC to DC power supply for a class and my question mainly revolves around the input and output of the whole thing. My source of confusion is where to include my DC output in a circuit such as I would assume that it would be the leftmost node of that full bridge rectifier...

Hey guys, My understanding of circuit analysis and the like is very minimal, and I have had a certain lack of understanding about something for a long time, and I feel I need to get a solid answer. I understand the fundamental difference between a voltage or potential difference and a...

I want to use a 12V DC Brushless permanent magnet motor as a wind powered electrical generator for a project. The motor is rated DC 12V and 1.20 amps. Once I reach an output of 12V does that means that I also have 1.2 Amps? Thank you.