In my defense-related work we call these “motor-generators.” And DC to AC motor-generators (i.e. a DC motor mechanically coupled to a three phase, AC generator) are still used for a… niche purpose that I can’t talk about. 
Now that’s a surprising fact.
Does anywhere else in the world use DC (supplied by commercial providers) as their default energy source? I assume New York was a case of legacy operations left over from the long-ago days when DC was the “It Girl”.
Big, tall, high voltage DC transmission lines are becoming more and more common to transfer electrical energy from point A to point B across landscapes. Once they reach a destination, though, the DC is converted to AC. And all electronic devices that plug into a wall outlet convert the AC (from the plug) to DC. However, I am not aware of any buildings/homes/structures that receive DC power.
Fucking shit, aren’t we all adults around here? You can say fuck in any forum.
My wife worked for a utility for forty years. She was a project manager who bossed hundred million dollar projects. She swears to this day that she doesn’t understand electricity and refuses to answer any question I put to her. So @Hatchie, you ain’t alone.
I feel the need to clarify-
I am not bragging about my knowledge of electricity. I know next to nothing. I was hoping to learn more in this thread. I have a soldering iron and a multimeter (they’re somewhere in these boxes!) and I want to master the use of both.
For the unfamiliar- A multimetr is an electrical doodad with a needle guage or a digital readout. By turning the setting dial and/or plugging the two wires into the correct holes, you can get basic information on different things-
How many volts are coming out of this battery?
Is this circuit complete or is there a gap?
How much resistance is this thing?
I am likely leaving some stuff out.
Multimeters come from extremely cheap to extremely expensive. The cheap ones break easily, are not precise and cannot be safely used on an outlet or anything plugged into an outet. The top of the line ones can be buried for a year, then dug up and thrown in a swimming pool for a day, then clog danced on, and still safely be connected to an outlet. They understandbly cost a lot and you don’t really need one unless your an electrician or something similar.
I can but I choose not to.
I usually choose not to, but I draw the line when explaining abbreviations of phrases that include “fuck.” That’s beyond seemly into silly.
Electricity is invisable magic that can kill you.
Let’s listen to Bartleby here and keep it clean for the children’s sake.
I’m sorry I asked. Never ask for an explantion of any abbreviation with an F in it.
I have two multimeters. I never figured out how to use the digital one.
With digital multimeters, there’s not a whole lot to figure out, even for novices. Want to measure a DC voltage? Set the dial to the highest scale on the DC voltage function and connect the meter to the source using test probes. Adjust the dial to lower scales to improve resolution (number of digits) as necessary. Same goes for AC voltage. For resistance, make 100% sure the circuit is not energized, connect the meter to the resistor/circuit/whatever, and adjust the knob for best resolution. Measuring current is the trickiest, as you need to connect one of the probes to a different jack on the meter, and “break” the circuit to make the measurement.
Having said that, one disadvantage with digital meters is that they will sometimes display “ghost voltages,” which can lead you to incorrect conclusions on what’s going on with the thing you’re measuring. This is due to the meter’s very high input impedance, and will occur when measuring a voltage that has a very high source resistance. Some digital meters have a “LoZ” switch to lower the input impedance and thus eliminate the ghost voltages.
Okay, I just got out my digital multimeter (ECG DM-859). Has a 9 volt battery.
I use a meter to check continuity 90% of the time. Put this into Ohm mode. It has three sockets, “V-ohm-m-A” , “COM” and “10ADC”. I assume I want to use the first two. But the black probe has gone missing, so I just stuck a hunk of lead-free solder in the COM hole (an amazingly snug fit, what are the odds?). Touching the red probe to the solder it reads “-1.” in point of fact, wherever I turn the dial in the ohm segment, I get -1, with the decimal point moving to different spots. Also, with the probe removed, it also reads -1. It also has a lighted display button which lights, so it can’t be a dead battery, or can it?
My analog meter never fails after years with the same double-A battery running it. The needle either swings or it doesn’t. Precision? Who needs it?
I am sorry if I came across as condescending. That was not my intent.
The multimeter I got from Dad was a needle display. About 5 years ago, something happened to it and it would not give readings anymore. I evntually had to throw it out. I don’t remember if my current multimeter is digital or not. It is still packed away somewhere.
I had a bunch of books by Forrest Mims on basic electricity. I couldn’t understand them and donated them to Goodwill. I think I kept Using Your Multimeter. I certainly hope so.
My problem was that I cannot grasp schematics. I don’t understand why they exist, how to read them (though I do know what some of the component symbols mean) or how to translate a schematic to an actual layout or vice versa.
Schematics just exist so that people like you and me cannot read them and feel excluded from the club.
If they just showed a picture of the circuit as it is actually laid out, that would be bad because people who have no business fooling around with these things might think they have permission to do things only the Experts should be allowed to do.
They exist to show a conceptual representation of a circuit. Just like a builder uses blueprints to construct a building, and not an actual building as a reference.
The hunk of solder may not be working properly. For one thing, the solder may not be making a good electrical contact. Secondly, on some DMMs, it won’t work without an actual banana plug, because the banana plug will bridge between two, separate contacts down inside the socket, which is necessary for it to work. At any rate, just buy a new meter. Here is one for $14, and it comes with probes.
Yep. And it allows a person to analyze the circuit. But as you and I are well aware, it’s also just a model, and it often doesn’t show the “parasitics” that can come into play that can cause instability in a circuit (wire resistance, leakage currents, coupling capacitance, ESR/ESL, ground loops, noise, etc.). This is what separates a green engineer from an experienced one… the latter will take these into account.
The difference is I can actually understand a blueprint.
The thing is in the Mims Radio Shack book, he showed an illustration of some basic circuit as it would appear in the real world. I understood what I was looking at, and I could build a copy with the right components. The facing page was a schematic of the same circuit. I still do not understand it.
This was the major obstacle to my further education. Up until that point, I had been doing at least average. The schematic stopped me in my tracks.
But we’re getting off track here. I would never try to repair an electronic circuit board, other than checking to see if there’s a gap in the circuitry such as a bad solder join. I wouldn’t pretend to have an understanding of why they do what they do or not do what they’re supposed to do.
It is possible I have been misusing the word. But I thought “circuit” technically meant pretty much any device using electricity connectd to both poles of the power source. Technically, when you switch on a flashlight you are completing a circuit.