Ac/dc Definition and 20 Threads

Kathy Joseph makes wonderful videos (and now a book) about the history of electricity. Her research is very thorough. I just watched the video below, and found it instructive. Especially interesting is how Nikola Tesla and Westinghouse in the USA got the fame and credit for three phase power...

I thought about this for some time but I can't seem to really understand the cause. Now I remember some time ago using a transformer for my self made soldering iron, I wound it to have the right temperature at about 45 VAC input but I guess I missed a bit , so that when I connected it to the 45...

I found this circuit (attached images) in an insulated pouch inside my basement's smoke detector compartment. It gets power from the hot line that feeds my smoke detector, and outputs power to a mystery load through a second outgoing romex wire (no idea where it goes). All my smoke detectors...

Hi, I'm trying to form an expression for a rectifier supplying a DC link with current, without actually rectifying a 3-phase input. Usage of the model is really only concerned with the RMS values and the active power drawn from the AC supply. The DC link is just a capacitor so that: dVDC/dt =...

Hello, I have a question about electric elements and their corresponding voltages. I am looking at powering a 1500W 120VAC element out of an ordinary kettle with a DC voltage supplied by solar panels. So, from what I understand, 120VAC represents the RMS voltage meaning that it would require...

Homework Statement In a AC to DC rectifier the DC signal was Vdc= (6.3+0.4)V and AC signal was Vac=(0.25+0.04)mV. What is the error on the quality factor of the rectifier? Homework Equations σQ=√((σr^2)/(Vdc^2 )+(Vr^2 σdc^2)/(Vdc^4 )) The Attempt at a Solution I know this is the correct...

Hello. I really don't get a concept of a way to generates negative voltage as a one of the supply voltage to typical OP-AMP. (Operational Amplifier) The output voltages is supposed to swing to more than 10 V thus supply voltages to OP-AMP should be +15V and -15V. I'm thinking of supply these...

Hello. I'm in the process of selecting materials for a voltage multiplier. I need to be able to vary a DC voltage source from 0-6kV, possibly with a regulated current up to 20mA...

Hello everyone, So some background on what I am doing. We have a pelican case with a bunch of PCBs that require DC voltage. I have purchased these power supplies (http://www.meanwell.com/search/EPS-65/EPS-65-spec.pdf ) to do the AC to DC conversion. They are located inside the Pelican case as...

I have a motor that is running off bridge-rectified mains voltage. There are no filtering capacitors across the rectifier output. When figuring the ratings needed for any switches in series with the motor, would I use the AC or DC ratings of the switch? My understanding is the biggest...

I have trouble with determining the type of resistor used in the following problem. A type of black box is connected to an AC/DC circuit. The values of U and I are given in the DC circuit, the value of R is not. The values of U and R are given in the AC circuit, the value of I is not. In...

Good day to all, I'm a newbie to the site and I have a quick question for all you electrical geniuses out there. I will start of with a bit of insight into my question. I am a maintenance Controls Technician in the automotive industry who has some experience, in my earlier years, doing...

in regards to power adapters, mainly the brick-type ones that come with laptops and external hard drives, how is the output current greater than the input current? for example, i see a laptop power brick with the following: input 100-240V~1.7A 50-60Hz output 18.5V == 3.5A 65W how...

Homework Statement How might you convert the generator in (http://www.aerospaceweb.org/question/propulsion/jet/generator.jpg) so that instead of producing alternating emf and current it will produce direct current? Would it be a steady D.C? Sketch a graph to show how the emf would vary with...

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...

Out of curiousity, I am wondering what happens, theoretically of course, if we place a 1.5V AC light bulb (which do not exist) onto a DC circuit with a 1.5V battery? What would happen if we connect this battery backwards on the circuit (positive to the negative terminal and vice versa). This...

Just a quick question for you guys out there. I have an AC/DC laptop power supply. I was thinking of using it for a few projects. Th power supply's output is 19 volts and 3.16 amps. My question is is 3.16 amps the max current that the power supply can take without frying? I mean the number of...

Hello this is my first posting. I have a device that I acquired from my old high school. It is a demonstration unit of AC and DC electricity generation. It has a small crank on one end. It is not equipped with permanent magnets in either the field or the armature. If I test the voltage off the...

What do AC/DC coupling mean in oscilloscope?

[SOLVED] oscillisope AC/DC button question Hi, with regards to the AC/DC button, what does it do... i mean i can google it and get stuff like: "a capacitor is placed in the signal path. the capacitor blocks DC signals but allows AC signals to pass." so ya, if i remember right, a...