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.

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120 views

Why does electricity have a phase?

Anyone who's seen the j in electrical formulas knows that electricity has a phase component as well as a magnitude. But where does the phase come from? Does it only ...
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2answers
24 views

DC analysis of common source MOSFET circuits to find gate voltage using different power supplies

simulate this circuit – Schematic created using CircuitLab strong text I am solving problems on DC analysis of MOSFET circuits. We are supposed to find various parameters like Id(Drain ...
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3answers
112 views

Why don't DC PSUs need a fuse?

This feels like a silly question, but after taking apart some of our 6W 12V DC power supplies I've noticed that none of them are fused. Out of curiosity more than anything else, I'm wondering why a ...
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1answer
61 views

How to open a small door using a dc motor?

I want to make something like this https://www.youtube.com/watch?v=xI8LUkUttfA&list=WL&index=34 I don't know where to find the motor or if the right motor will be strong enough to lift the ...
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1answer
47 views

Typical Laptop DC Jack Voltage [on hold]

I have a laptop AC adapter with a DC output jack. The laptop does not power on nor does it show indication of receiving power (power LEDs do not light up). The AC adapter is rated for output of 19.5 ...
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0answers
45 views

Inverter vs Rotating Machine

My question is in how to relate a 3 phase PV inverter to a classical rotating machine. How is the machines power angle realized by the inverter? In power flow studies, real power flows by ...
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2answers
68 views

Need help with a VU meter analog signal

I am making an Arduino VU meter. I need to convert an analog AC audio signal to a varying positive DC signal. I would like the following outputs: 2.5 V output at 0 V input (from VM1); 5 V at maximum ...
0
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1answer
26 views

please help me choose power mosfet for multilevel inverter

I am doing my senior project on cascaded multilevel inverter. I am planning to use MOSFETs as switches in my project.Please kindly give me instructions and respective formulas for getting right ...
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1answer
55 views

Make a brushed DC motor move “free”

I want to place a DC motor on the driveshaft of a marine steam engine. Since i do not want to loose or add power to the drive but only having the motor there for backup reasons, i want to let the DC ...
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1answer
19 views

reverse load on dc motor( series/shunt) and its speed control

if dc motor produces 10 Nm torque , and load acting on dc motor in reverse direction produces 6 Nm , then net torque is 10-6= 4Nm, dc motor consumes current corresponding to 4Nm , and so speed becomes ...
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0answers
52 views

Reverse engineering MOSFET power circuit

I'm looking at a portable heater circuit that uses a 1.4 Ohm resistive load as the heating element. The circuit in question uses an N-channel dual output mosfet, and on the other side of the board a ...
0
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3answers
45 views

Switch current rating AC vs DC

I'm looking for a high current DC switch (able to switch something like 5V@30A) and I've encountered several DPDT that might do what I need, however they are only rated for AC applications (3A@250VAC ...
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3answers
62 views

Controlling audio singal with digital potentiometer?

I am very confused about how to go about using my digital potentiometer to control an audio signal. I have a MCP4231 digital pot and would like to use it as a MCU controlled variable resistor for gain ...
0
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1answer
137 views

Dangerous Power Supply [closed]

I recently bought a 3D printer from the USA and imported it to the UK, it came with a Chinese 12v DC 30 Amp power regulator. The PSU is a metal enclosed box. It can take 220 Volts +/-15% so it should ...
0
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0answers
38 views

Transformer equivalent circuit [duplicate]

If anybody has any experience with practical transformer schematics and analysis techniques, could you please explain how to solve this question, i have looked all over multiple websites and there is ...
0
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2answers
57 views

how to compensate power drains in dc circuits?

This has been on my mind for a while. Lets just take any electronics device. Lets say a mobile phone or a laptop. They have fixed voltage and current, but some components needs higher voltage/current ...
0
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1answer
40 views

Low Breakover Voltage Diac [closed]

I wanted to know if there is commercially available Diacs with Breakover Voltage of 20V or less. I tried to find in the internet but always ending up to Diacs with Breakover Voltage of around 30V or ...
0
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0answers
62 views

transformer (no load test)

If anybody has any experience with practical transformer schematics and analysis techniques, could you please explain how to solve this question, i have looked all over multiple websites and there ...
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1answer
44 views

Cable parameters calculation for a long 1000 V DC cable

How to calculate the current that is needed to charge the cable capacitance and inductance while switching DC power supply ON? And the current that is released from the cable inductance and ...
0
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1answer
36 views

Shared Voltmeter for 2 DC Circuits at Different Voltages (battery & solar)

I want to use one panel mount voltmeter (Powerwerx PanelDVM) for measuring both my 12VDC Battery output and the input voltage from a Solar panel ,which has a higher DC Voltage. This all is hooked to a ...
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3answers
66 views

bulbs in series with individual power [closed]

Three lamps (with individual power of 30W , 40W and 50W ) are connected in series to a source of 100V . What is the voltage to the terminals of the 40W lamp ?
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3answers
95 views

How does a bridge rectifier work exactly?

If this question was posted before, please let me know. I searched for "how does a bridge rectifier work" and did not find an answer. The part that I especially find confusing is when I have the ...
3
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1answer
49 views

Circuits problem

simulate this circuit – Schematic created using CircuitLab My question is what's the voltage between C and D? R7=1kΩ Vc-Vd = (Vc-Vb)/1000 + (Vb-Va)/1000 + (Va-Vd)/1000 = ...
5
votes
2answers
87 views

How do I combine multiple A/C and D/C power sources into one electrical system? [closed]

I'm looking to design an off-grid power system for my house. I'm a complete novice at this point but I'm willing to do a lot of reading to complete the project. There is a lot I still don't yet know ...
2
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1answer
52 views

should I use high voltage or high current to burn carbon rods to dust

I want to burn carbon rods in a vacuum chamber to coat samples in carbon and need the carbon rods to be completely evaporated (worn out /eroded) through electrical power. I also need the +ve ...
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2answers
69 views

Can pulsating DC be used for induction heating?

I want to make an induction heater work using a 12 v, 35 A-h battery(used in cars). I don't want to use an inverter. Will a pulsating DC input to the induction heater make it work?
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2answers
55 views

Create a Time-Variable Dc Power Source

For some reason, I need a Time-Variable DC power source that changes it's value according to time. I need this changing of value to be controllable. I'll put it this way : Say I have a 12 volt DC ...
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3answers
91 views

Why does a simple circuit drain a battery slowly?

OK, so if you directly connect the two terminals of a battery, there is very little resistance in the circuit and you will drain the battery very quickly. However if you have a very simple circuit, ...
3
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1answer
38 views

How to select a DC cable connection type based on current?

I have a battery and DC-DC converter solution that I've ordered. The solution will output 20A continuously at 5V, and will sometimes pulse up to 30A for durations up to 10 seconds. I believe voltage ...
0
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3answers
56 views

Are DC induction motors possible?

Forgive me if I am asking something absurd, I really do not understand much about electric motors. After reading the answers of Why does a Tesla car use an AC motor instead of a DC one? , I got ...
2
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3answers
111 views

How to analyze this Diode Circuit by hand?

I need to analyze this circuit by hand, I'm a Mechanical Engineer, so I really have no idea what I'm doing here. I thought about doing the parallel of the 2 top resistances and same for the bottom ...
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0answers
26 views

DC Brush Commutation system simulation

Hello plz help me regarding simulation of brush DC motor Commutation system to analyse the commutation system .. as i am from mechanical background but needs some simulaton to corelate electrical ...
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2answers
58 views

Powering a rpi and accessory of a 9v battery [closed]

We are trying to use a raspberry pi to record the current going through a dc circuit. The circuit we are trying to measure the current in is powered by a car battery. We have no idea how to record the ...
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2answers
24 views

Does this DC pump and similar ones output at different rates or at one constant pressure/air flow rate?

https://www.youtube.com/watch?v=nLLq4CB9EkU [3 minute video demonstrating a small diaphragm pump driven by a brush DC motor.] I would like to use a DC diaphragm pump similar to this, small in size ...
2
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1answer
139 views

DC Motor as a Generator Voltage and Current

Is there any way to calculate the expected voltage and current, assuming I am turning it at the specified RPM value, when using a DC motor as a generator without physically testing it? In my case I ...
0
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1answer
97 views

Can I use a 220v AC rated switch for 220v 120Hz DC?

so I have this setup: Bridge Rectifier has no Capacitors! So it outputs 120Hz DC I had this without the bridge rectifier, but then, since it's AC and you only break one side the current would jump ...
2
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0answers
55 views

Reducing noise for a TDA8947J amplifier

I have an PC audio amplifier using TDA8947. One 30W subwoofer and two satellites. It produces a lot of background noise and I would like to cut it down a bit. The noise is all in the subwoofer. It ...
3
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1answer
119 views

should AC ground (earth) and DC ground be connected? [duplicate]

I have a power supply (AC --> DC) powering an microcontroller and DC electric motors. I also have the same AC powering a speed controller, which feeds to an AC motor. Should I be connecting the ...
2
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2answers
126 views

+5V and -5V power supply from 12V DC

I'm creating an RGB switcher for a car video system and would like to use the MAX466 chip, which needs -5V, GND and +5V. I have no idea how to change normal 12V DC (car battery) to dual 5V. I found ...
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2answers
110 views

Why does the original Nintendo take 9V AC instead of 9V DC?

i have found an old Nintendo NES 9V wall adapter which is in fact not an AC DC adapter because it's an AC AC adapter. It's the first time i see an AC adapter that ouputs alternating current, Why did ...
0
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1answer
67 views

Can I share the ground between 2 ac adapters with different outputs? [duplicate]

I know there are other ways I can do this, but I'm a little curious about this anyway. Basically, I have a breadboard that's mounted on a typical base that has the typical three posts I can hook ...
0
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2answers
84 views

Does a Breadboard Compatible DC Barrel Jack Have to be Connected to Positive and Ground to Receive Power from an Outlet?

I am using an Arduino to control an electric lock strike but I don't know how to power the lock with sufficient power. To control the lock from the Arduino, I am using a TIP31 transistor (It is NPN). ...
0
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1answer
51 views

Connecting a +12V DC wire to a Voltage Regulator with 4 pinouts

The voltage regulator I'm using has 4 pins (2 in, 2 out) pictured below. The reason I purchased this regulator is that I want to convert +12V DC in to +5V DC current for connecting a Sony Projector ...
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2answers
82 views

Optoisolator not turning off

I'm using an optoisolator for high side switching a Nixie tube. For some reason, the optoisolator is not fully turning off, allowing the a very minimal amount of current to flow through the Nixie ...
0
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1answer
56 views

Fan Control using Motor Driver, looking for suitable solutions

I want to control the speed of a fan (which is a 2-phase brushless DC motor). I am currently using a suitable power supply to run the fans. My source is a Data Acquisition device that outputs up to ...
1
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0answers
75 views

How can I convert very high, fluctuating, AC voltage to 240VAC at 50Hz?

I'm about to finish a generator-alternator setup which will generate 9-phase AC electricity at (as yet unknown) very high voltage, most likely around 4800V. I'm not sure what the frequency will be, as ...
0
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1answer
42 views

How Number of commutator segments,air gap between the segments of brush dc motor affect on performance of DC motor..?

plese help me about how Number of commutator segments,air gap between the commutator segments of brush dc motor affect on performance of DC motor..?? now if we we change the number of commutator ...
0
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1answer
80 views

Diode selection [duplicate]

I have a very simple circuit but have no idea on what or how to chose a diode for it. It is for a uni project and we are being marked on our justification for choosing the diodes. Is there such ...
0
votes
3answers
120 views

Can voltages be different if watts are the same? Does DC vs. AC change this?

I'm currently building a home in a van, it's my first tango with electrical engineering. I watched a video on voltages and amps and my understanding is basically like so: a battery is like a water ...
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1answer
71 views

DC-DC power supply module help needed [closed]

I have purchased this little brick (link below) that I though would allow me to input for example 12V DC and output a lower output voltage, for example 5V DC, but I'm now testing it and it seems to ...