Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [dc]

DC stands for Direct Current, which means the flow of electric charge in a single direction. Examples of a DC source are batteries, solar panels, and dynamos.

DC stands for Direct Current which means the flow of electric charge in a single direction, as opposed to Alternating Current which means the flow of electric charge continually switches direction at a particular frequency.

DC is generally used in low-voltage applications for powering (control) circuits used in many gadgets and electronic systems.

Examples of DC sources are:

  • batteries
  • solar panels
  • dynamos
  • thermocouples
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How does a capacitor block DC?

I am confused with this! How does a capacitor block DC? I have seen many circuits using capacitors powered by a DC supply. So, if capacitor blocks DC, why should it be used in such circuits? Also, the voltage rating is mentioned as a DC value on…
Arun M
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Using clothesline steel core wire rope for AC and DC

As I am currently in a war zone, I don't have many options for cabling. I found this clothesline (steel core plastic wire rope) that appears to be one mm of diameter (steel core diameter.) 13 meters of it measured 7 ohms resistance. Edit: It is 3.8…
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230V AC to 5V DC converter, lossless

Is there any IC which converts 230V AC to 5V DC? As lossless as possible. I want to connect my microcontroller to an ordinary electrical socket and I don't have enough space available. Thanks.
arminb
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What would happen if I connect two different DC voltage sources in parallel?

I have a computer power supply that I'm hacking together as a bench supply. For this particular model to power on, I need a minimum load across both +5V and +12V. "Easy," I thought, "I'll just connect both +5 and +12 to my power resistor!" And it…
rascher
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Switching DC with MOSFET: p-Channel or n-Channel; Low Side Load or High Side Load?

I think, it is time I understand working principle of MOSFET transistors... Suppose that; I want to switch voltage on a resistive load by a MOSFET transistor. Any control signal between -500V and +500V can be easily generated. The transistor…
hkBattousai
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What to do with third contact in DC barrel plug with only two input contacts

My AC-DC adapter gives output of 12V and GND. I tried to search for suitable DC barrel plugs and found that most of them have three terminals So, pin 1 is positive in my case. 1. Which pin should I connect to GND, 2 or 3, in my PCB? 2. What should…
zud
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Can I reduce voltage from 3.3V to 1.8V using a 1.5V battery?

I am interfacing to an EEPROM that works via SPI at 1.8V; unfortunately I do not have a 1.8V power source around and being this a weekend project, I wanted to complete it without going to the shop. I asked a skilled friend an advice and he suggested…
gdm85
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How do I power/wire something that is rotating constantly WITHOUT extra batteries?

So I want to make a Lazy Susan that is rotating constantly in one direction. I also want to have some other things on top such as neon signs, moving things, and etc. Problem is I want this to all run off of one DC source. Problem is I cannot figure…
Sie
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Why does a capacitor block DC and not AC?

If someone can explain why a capacitor blocks DC, but not AC, with some math, I will understand all of that much better. I know that there are picture animations illustrating this, but I really want to know this a little bit more detailed.
Junior
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How do the tiny AC->USB power supplies work?

The iPhone and Kindle both come with tiny power supplies that take in 120v AC and output around 5V at 0.85 to 1 amp. They seem to be too small and light to have a transformer, and generate very little heat. What is the electrical topology of these…
ObscureRobot
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Why does inverter synchronization with the grid take 5 minutes?

We had some solar panels & an inverter installed recently. Every time the inverter is turned on (after maintenance or with the first light of the day) it has to synchronize its generation phase with the grid, and it is easy to understand. But why…
dvdmn
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Circuit for measuring high voltage DC voltage (up to 1000V)

I am a final year E&E student and I am trying to built a power meter that must be able to measure quite high DC voltages, up to 1000 V DC. I am measuring with a simple 12-bit ADC that has an input voltage range of 0 - 2.5 V. Would a simple voltage…
Eduan Shuda
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What are the highest DC and AC voltages or currents that can be considered as safe?

By safe I mean safe for us when we touch a wire that is not insulated. I have heard that human body resistance is normally 50k Ohm when dry and 20K Ohm when wet. Therefore, these voltages or currents should be safe for a person who is wet. It should…
Amit Hasan
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Short circuit = no power?

Now I want to build stuff and I'm really interested in learning things (consider I'm starting from scratch). So I'm reading all of this website and the following line in this article got me scratching my head for some time: [about the power…
qreon
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What does RU (UR) label on DC power relays mean?

I'm trying to figure out what does RU or maybe UR label mean on the body of many many relays. It's labeled almost on all (I've seen so far) DC relays which make me very curious :). Any suggestions?
Timur Fayzrakhmanov
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