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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, dynamos.

39
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3answers
51k views

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 +...
60
votes
9answers
223k views

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, ...
4
votes
5answers
376 views

Is direct current really better for pumped-storage hydroelectricity facilities?

Currently the article equivalent to War of the Currents in Russian Wikipedia section says that direct current is beneficial to pumped-storage hydroelectricity plants and provides no reference to that ...
4
votes
6answers
6k views

I want to build a DC powered computer, what are the gotchas, where are the parts?

Google builds its servers with a Battery in the box so that they don't need a UPS. I'm wanting to do the same, but I'm wondering what all the gotchas might be for doing this, and where I'll find the ...
5
votes
1answer
8k views

Dc isolation (transformer?)

I need to isolate the dc input from the dc current inside the circuit (both 9v), in the same way as a 1:1 transformer isolates the AC current inside the circuit from the input AC. I already found out ...
1
vote
1answer
1k views

At DC frequency, how long can wire be until signal attenuates almost completely?

Just got curious about this last night when I was wiring a couple of LEDs on my brother's long board. For a simple DC circuit (Battery, resistor, LED), how long can I stretch the wire until the power ...
13
votes
5answers
7k views

24VAC/5VDC power supply design

I am planning to create a water valve controller using an MCU and a set of solenoid-controlled valves. The solenoids run on 24VAC (40mA inrush, 20mA holding). The MCU is on a board that draws ~100mA, ...
6
votes
3answers
9k views

Why is high voltage AC more common than high voltage DC?

Why is that high voltage AC is more commonly found than High voltage DC? Example my battery powered fly swatter and fluorescent lamp both use high voltage AC. Why can't these devices increase the DC ...
1
vote
6answers
2k views

dc motor and hung (not stable) pic

I'm running a dc motor using PIC16 family microprocessor. I connect it to my pc, I can send a command to run the motor in certain speed or stop. It works for small motor (3V, 100 mA). But the moment ...
14
votes
4answers
8k views

What is the role of capacitors in DC circuits like motherboard, graphic card etc?

I was just reading in Capacitors in DC Circuits that "Capacitors do not play an important role in DC circuits because it is impossible for a steady current to flow across a capacitor". I think it ...
5
votes
2answers
3k views

Actuator can use either 24V DC or 24V AC. Which should I choose?

I will be using a damper actuator which can have either an AC or DC power supply. I do not have any strong preference for either, so what would you recommend? I assume that transforming 230V AC to 24V ...
1
vote
3answers
401 views

Use PSU as replace for broken source +12Vdc 3.33A?

I need 12Vdc 3.33A source power for Silicon Graphics 1600sw display, I have two ATX computer power supply. Is it possible to use these PSU as replace for broken 12Vdc 3.33A adapter ? UPDATE: I ...
2
votes
1answer
324 views

DC-DC Regulator/Converter to Power Robot and Laptop

I have a small form factor Lenovo IdeaCentre PC that I would like to use as the primary controller for a large scale tanked robot. I've ironed out the accessory connections using usb->server ...
17
votes
3answers
26k views

DC biasing audio signal

I have seen a few different ways of adding DC bias to an audio signal. I have simulated them and they all give me similar results, but I cant Figure out is why choose A over B or C. My audio source ...
3
votes
2answers
5k views

How would I create a voltage doubler and what parts would I need?

I'd like to make a voltage doubler, I've read up on wikipedia and also here. My issue is that I have DC input and I need DC output, first is this even possible, second, if so the problem I'm having, ...
4
votes
5answers
9k views

how to build a high-power (4kW) switched-mode DC-DC converter?

I would like to build a switched-mode DC-to-DC converter which should support up to 4000 W of power. It should be able to act as a CCCV power-supply, so supply a constant current Imax up to the point ...
2
votes
1answer
3k views

DC restoration of a video signal

I have a composite PAL/NTSC video signal. One problem I am having is getting a reliable sync signal from it; picture brightness causes the sync pulse (normally 0.3V) to vary; so much that my scope won'...
13
votes
4answers
19k views

12V DC UPS for Network Equipment

My requirement is to keep running supply of low power devices like DSL modems, etc. Most of these devices input 12V/9V DC so i don't see the value in using ordinary UPS which converts DC to AC then ...
15
votes
3answers
55k views

Wiring a DC socket - why three pins?

I have this DC socket: Which I intend to wire up to a circuit to provide power. I have a DC power supply which has a positive tip polarity. I'm good to go and wire up the socket but I am a little ...
1
vote
5answers
342 views

Crude/inexpensive AC to DC transformer

I am working on a circuit that is completly powered by 5VDC from a USB port. The circuit uses SSR's to turn on and off 120VAC from a standard wall plug; the 120VAC powers a high-power heater of sorts. ...
5
votes
4answers
3k views

Can a 2-prong AC/DC converter switch polarity based on inverting the plug?

I got an electrical engineering degree 15 years ago that I barely use. Although I bought a fairly fancy multimeter, I will freely admit to having only a vague recollection of what I did back then... ...
4
votes
2answers
615 views

Best Circuit Design for a 12VDC Wall-Wart > Ouput Voltage of 1.5V (Replacing Alkaline Batteries)

I have multiple stationary baby items for my son Oliver that require a serious supply of batteries each month. I would like to hook a few of these stationary items up to wall warts to conserve the ...
9
votes
2answers
10k views

Methods of filtering noise caused by DC brush motors

I am looking for any information that would help me reduce the power rail noise and EMI of DC brush motors. I am building a robot that is powered by 2 x 250 W 24V DC motors. Thank you in advance
8
votes
2answers
3k views

Can Arduino Mega handle 6 motors independently

I wonder if anyone can help me I am modifying an ROV and thinking of using Arduino Mega I am new to electronics and robotics and wonder if the Arduino Mega can control 6 DC motors independently as ...
1
vote
1answer
2k views

Measuring Voltage of Unknown Type

My circuit is almost identical to the Wikipedia but with 5V in, 1pF cap, 4 pieces of IN4004 diodes. I am not certain whether it is AC or DC here and there (actually I do but not want to break my ...
4
votes
4answers
5k views

DIY Beginner's DC Power Supply? [closed]

My school uses HY 3005D-3 but I want to do it myself to save on $. Before opening it, I ask for tips about: not-to-break-it, cheap DC supply and DIY-materials (not that I know them soon). So how to ...
-1
votes
4answers
2k views

dc level shifter

I am a high school student. Please help me, i want shift a 24 volts at the input to 6v on the output!! i need a dc level shifter but i dont know its contents!!
1
vote
2answers
1k views

DC Gear motor Operation

I just bought a DC gear motor- I'm trying to spin a 20 pound disk. I realize I need to hook it up to a power source, but I'm having trouble figuring out the proper source. PS I also got a DC speed ...
6
votes
2answers
2k views

Can I combine the power supply?

Here's the circuit I'm working on, it's a robotic stringed musical instrument thing, that uses 6 DC motors and an Arduino Duemilanove - The resistors are 0.25w 1KΩ The transistors are TIP122 ...
4
votes
5answers
3k views

How to deal with a DC adapter with irregular voltage output?

Background information: I tried hard to get a Schmitt-trigger working, but it kept failing. By accident I figured out, that my AC-to-DC adapter produces a very irregular voltage output (I could hear ...
7
votes
3answers
4k views

Simple circuits 1.5 V DC to 9 V DC

Anyone got any super simple circuit designs for converting 1.5 V DC to 9 V DC? Maybe something that uses a couple of transistors would be good?
12
votes
6answers
28k views

Very Slow Electric Motor

A customer has asked: I want to slow down a small hobby sized DC motor to a user variable range that runs from slow to zero RPM. I would simply use a wall wart for a power supply and a ...
3
votes
2answers
3k views

How do you read newer HDD motors (DC/Brushless) into arduino? (like stepper motors)

We had a version of the HDDJ working with an arduino reading an old stepper motor (with 4 wires), then sending serial data to processing, using a midi library, and midiox + midiyoke. Having trouble ...