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.

learn more… | top users | synonyms

1
vote
1answer
47 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 ...
-1
votes
1answer
18 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 ...
0
votes
0answers
47 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
votes
3answers
42 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 ...
1
vote
3answers
58 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 ...
-2
votes
0answers
76 views

Power circuit analysis [closed]

2 questions 1) does anybody on this website have any knowledge of transformers and power system? (just to make sure i'm not on the wrong site) 2) can someone explain how to draw a transformer ...
-2
votes
0answers
43 views

I am looking for a 12V DC motor that can supply 36W power… [closed]

Where is the best place to buy something like this? It is needed for an automotive application - It will run off the battery/alternator and need to supply 36W. I need to apply 3000N of force over ...
0
votes
1answer
131 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
votes
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
votes
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
votes
1answer
38 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
votes
0answers
60 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 ...
0
votes
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
votes
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 ...
-6
votes
3answers
65 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 ?
1
vote
3answers
92 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
votes
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
85 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
votes
1answer
49 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 ...
0
votes
2answers
68 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?
0
votes
2answers
54 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 ...
0
votes
3answers
89 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
votes
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
votes
3answers
53 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
votes
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 ...
-1
votes
0answers
25 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 ...
-6
votes
2answers
56 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 ...
0
votes
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
votes
1answer
127 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
votes
1answer
93 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
votes
0answers
42 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
votes
1answer
114 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
votes
2answers
121 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 ...
0
votes
2answers
108 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
votes
1answer
65 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
votes
2answers
80 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
votes
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 ...
1
vote
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
votes
1answer
54 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
vote
0answers
70 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
votes
1answer
40 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
votes
1answer
79 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
115 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 ...
-1
votes
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 ...
0
votes
6answers
202 views

How do you find the voltage across a capacitor at time t= 0 and t = infinity?

Here is a diagram of the circuit, I am confused about problems a and b. How do I go about solving these two problems? Thanks! By the way you don't have to tell me the answer, I just want to ...
0
votes
1answer
114 views

Op amp based DC-DC voltage doubler

I have a LM471 op-amp and a single DC 5V source. Is it possible to double the source voltage using this op-amp? Can the op-amp be powered by the very singnal to be ...
0
votes
2answers
65 views

Crude simulation of a dc motor

I have a 24V battery bank and would like to discharge it in order to test the performance of different solar charge controllers. Eventually the batteries will supply a 2hp (1500W) DC motor and it is ...
0
votes
2answers
66 views

Can I use aluminum tape or naked two paralleled striped cables to connect parallel LED strips?

I need to parallel connected couple dozen cut LED strips. The total current reaching them won't exceed around 2 amps. My constraint: I can not order any more components for the job. My tools: ...
0
votes
3answers
154 views

Is there a way to adjust the DC Voltage

I have a source (1) of power which can be adjusted from 1-5 Volts and 40 mAmps. I have another source (2) of power which delivers a constant 5 Volts and 400 mAmps. I want to build a circuit which ...
0
votes
2answers
106 views

Power and control 3 phase ac induction motors with dc source

Background So we are making a drive system to be used in a medium sized catamaran. The catamaran will use two water-jets powered by two 3 phase 380v ac induction motors. The entire system will be ...