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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.

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Separate two batteries getting charged by one charger with diodes?

I've got a robot that I use two batteries on. One of the batteries power the servos and engines and the other is for the digital boards. The servos need 5 V. The control board and LCD run on 5&...
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143 views

Function of the Third Pin Inside Laptop Barrel Connector

So I've been doing research on barrel pin connectors, and have been trying to apply this knowledge to understand laptop barrel connectors, specifically. My confusion relates to the function of the ...
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51 views

stall dc motor 12 volt for long time

hi every one i make water cooling system for dc motor 12 volt how can i make the dc motor hot to test the system ? whan i stall the dc motor the wires get very hot before that effect the motor and i ...
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DC Battery Stability

I have a 12 V load that works by connecting an adapter from the AC socket and this adapter output 12v to the load. I decided to make a 12 v battery that can charged and the feed this load , all the ...
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54 views

Making a DC motor turn in saturation and cutoff modes of an NPN transistor

simulate this circuit – Schematic created using CircuitLab So I have a DC motor that should turn with light on LDR and should stop when I cover LDR or turn off the lights. Basically the ...
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42 views

DC generating plant [closed]

What would happen if positive terminal of Dc get grounded in any DC generating plant? Will it impact negative terminal and burn it?
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46 views

i don't understand the KVL solution to this question?

this is part of the solution of a previous exam and there are some things i don't understand about it 1- why did he assume the value of current at the 12 Ohm resistor to be 0.5A without any ...
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1answer
83 views

Simple way to create a disturbance on DC power

First of all, i must say that I am a software engineer, with very-low to no experience in circuits designs, and a very rudimentary understanding of electrical engineering and circuits. 101 really. ...
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3answers
1k views

Will a DC circuit breaker trip due to high voltage?

Will a DC circuit breaker trip due to high voltage (exceeding voltage rating) or will it only trip because of high current? For example, if you have a 40 Amp DC circuit breaker which also has a 32 ...
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1answer
117 views

Two 9 V batteries in parallel

I don't know where else to ask this question and I think this is the best place so I'll ask here. I'm making a remote controlled boat that uses two DC motor controlled by a L293D motor driver chip. ...
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3answers
76 views

Moving Ground in between resistors in series

What happens when you move Ground to the given point? How does it affect the Voltage and the Resistors after moving it in the circuit? Missing values: .Current (I)= 30mA (V.R1)= 15V (V.R2)= 3.6V ...
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31 views

Finding the supply voltage, knowing the resistance and current

I am learning the basics of electrotechnics. I had this task for my university that I failed doing and I want to learn how to solve it anyway. Thanks for assistance! :) Here is the exercise task: I ...
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100 views

Correct way to do “power injection” from multiple DC supplies?

I'm using a PixLite controller to run a bunch of pixel LED strips. Since I'm sticking to 5V I need to use multiple power supplies (PSUs) to "inject" extra power for the number of LEDs I'm running. ...
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51 views

Summing up batteries

I am a little confused, shouldn't I take into account the maximum battery voltage when trying to add-up batteries in order to achieve certain voltage? For instance if I want to drive a 48V 1000W DC ...
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1answer
33 views

Single MOSFET motor driver with oscillation on output

I'm trying to drive a small DC motor with a PWM with the circuit below, where I'm using a TIL111 optocoupler and a IRF510N MOSFET. The PWM (50% duty cycle) is generated by a MCU STM32F103C8T6, the +3....
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1answer
72 views

Source Transformation

Ok, I have modified my question again about the same circuit seen below: I have to simplify the circuit using source transformation and then find the current ix. I have attached my attempted ...
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2answers
145 views

How is it possible to ever have frequency on a DC circuit?

Preface Please read this carefully. I put a lot of time into it and am genuinely attempting to understand. I've read numerous articles about DC and AC circuits and searched numerous places to get ...
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3answers
52 views

Convert Battery to AC @ same voltage

I have some LED fair lights that run on 30V @ 0.4A supplied from an AC mains supply. They have been wired to flash using some form of notification to the AC (I'm not interested in them flashing). I ...
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KCL / KVL Circuit Analysis

I have a question regarding using KCL / KVL to analyse the circuit below to find all currents and voltages. My question is : When performing KCL at the top centered node, what way should I assume ...
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0answers
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how to choose/design a capacitor value for surge current(for protection) for DC brush motor?

I am driving a DC BRUSH Motor at 30.V.D.C and the current is 300 Millie ampere, it is powered by L.M.317 I.C .My sir is suggesting to provide a capacitor as a protection form surge/peak current ...
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1answer
113 views

Can identical DC power supplies with common ground produce varying voltage on same circuit?

For large installations of 5V LEDs, this PixLite page suggests using "power injection" from supplemental power supplies. Their wiring sample says: Note that the DC ground of all power supplies ...
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1answer
60 views

Opamp confusion

I would really appreciate a little help here if someone explain me why his Voltage is 4v while mine is 10/3 and one more thing: whats the point of Applying KCL at node 1 when 5v is already known at ...
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1answer
56 views

Can the metal body of a dc motor be used as negative terminal for that motor?

I need to power a micro DC gearmotor (6V, 0.5A), but due to the position in which it needs to be placed, i can only access the positive terminal (of that motor). It is possible however to connect the ...
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1answer
112 views

Where to place a diode - DC 12v motor controller [duplicate]

I'm building a controller for a DC motor. I'm using a 12V DC motor from windscreen wipers. Here is my circuit diagram and a video of the simulation I made. https://www.youtube.com/watch?v=...
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1answer
86 views

Discharging 18650 battery at constant rate

Hello I am planning to do some tests with a 18650. In these tests my goal is to measure required time to discharge them with different discharge current rates (1A, 2A, 5A and so on...) The op amp ...
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1answer
48 views

Current change through Series resistors

My question surrounds a simple scenario. I have a 12V DC power source connected to 2.2kΩ/10kΩ/22kΩ resistors in series. For an assignment, I have theoretically calculated Voltage drops across all ...
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1answer
83 views

DC motor at open load

Why at no load condition armature current is very small in DC series motor. Please explain me, what exactly no load mean. Thank you.
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78 views

DC motor induced emf in field winding

In case of DC motor even if DC voltage is applied, due to commutator an AC current flows through armature ,then due to this changing current, does any voltage is induced across the field winding? ...
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2answers
37 views

How to represent a variable DC supply potential difference on a circuit diagram

I have a circuit diagram for a physics experiment. On the diagram I have represented a variable DC supply, but I would like to know where do I write the potential difference selected on the variable ...
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1answer
41 views

DC shunt motor rotation

ln case of dc shunt motor , how can a field winding produce rotational torque,whose field current is very small when compared to armature current. i mean how can it provide so much attraction ? ...
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2answers
73 views

Output voltage of a rectifier

Is the output DC voltage of any rectifier (Halfwave, Fullwave or bridge) simply equal to \$\sqrt{2}\$ times Phase to neutral AC input voltage? Or does every rectifier circuit have its own formula to ...
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1answer
77 views

AC input not matching DC output

I know this might sound stupid but it has me stumped. I am trying to calculate the average AC power input required for a few electrical devices which will be connected to a generator. The issue I'm ...
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3answers
423 views

Connecting multiple Fairy lights in parallel to single power source

The above diagram shows how I'm about the connect the LEDs, info regarding the drop forward voltage been taken from: Calculating forward voltage for a string of fairy lights: multimeter shows "1&...
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1answer
45 views

Connecting unbalanced parallel battery strings to a common DC bus

We are currently researching a system in the design phase which will use 2 parallel 48V lithium battery strings. Each string will have a battery management system ensuring the cells are balanced. ...
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5answers
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What kind of tool is used to record a voltage over time to a PC file like a waveform?

I don't have any training but am doing some hobby electronics. I would like to record a change in voltage over time, sampled at around 100+ kHz. Ideally, I'd like to record around 20-30 min of two ...
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3answers
77 views

Is it possible to use DC-restoration as a half-wave rectifier?

A simple DC-retoration circuit: seems to do the about the same job as a half-wave rectifier, is it standard to use these two circuit instead of each other ? I tried to increase the capacitance of ...
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1answer
39 views

DC motor power generation

Can any one tell me If we rotate a DC motor(1800w) in its full speed how much electric power(as a generator) it will generate?
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4answers
111 views

Determine the current through a voltage source for nodal analysis

I'm struggling with a problem our professor gave us, which states: "In the following circuit, find the value of the resistor R_x so that the power consumed by the resistor R1 is the maximum." ...
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1answer
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How can I tell whether a DC device will accept a greater voltage than stated? [closed]

Over the time, as an amateur, I've developed a sense that DC powered devices with internal circuitry should be fed with the voltage stated on the case. Having seen certain devices (e.g a portable USB ...
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2answers
80 views

Capacitor actual value with DC bias

I did find this answer which explained why the capacitor is affected by the DC bias, however, my question is more on the application. Let's say I have a capacitor for which I have the DC bias ...
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1answer
81 views

What is the main difference between AC and DC generator basic working principles? [closed]

I cannot understand the main difference on AC- DC generator basic working principles. Lets consider how a loop wire works with a magnetic flux inside a DC generator briefly. Whenever the sides of the ...
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1answer
80 views

Can I safely connect 20 Raspberry Pi Zeros to this 5V 10A power adapter

I want to connect 20 Raspberry Pi Zeros (5V, .200-.300A) to a 5V 10A power supply shown below. The setup Im planning will look like the photo below but with many more Raspberry Pis. I posted my setup ...
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3answers
149 views

Can I touch voltage?

After watched this man this man, I have some questions. He touched 170 VDC, what is max DC voltage can I touch when I dry? And wet? What is max AC voltage can I touch when I dry? And wet? Is ...
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2answers
94 views

Precision resettable fuses

I am a scientist, and I have found myself needing to interface two disparate pieces of equipment. I have a precise, automatically controlled current source that I wish to interface to a very ...
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2answers
92 views

Can DC voltage on a DC relay switch an AC circuit?

Can I use a DC relay with 5VDC to switch a 120V highpowered circuit? Thanks
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0answers
17 views

With what can I replace power supply Foshan Hanyi S126SMD3 [duplicate]

I have an infrared sauna and it seems like the power supply is broken. I want to replace it, but it's really hard to find the original one: Foshan Hanyi S126SMD3 http://www.zidonghua.com.cn/...
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3answers
220 views

Why are there current and voltage limits in a DC bench power supply?

I have a few questions about bench power supplies. Why does a DC PSU have a low output voltage limit, usually in the range of 18V-24V? Why is there a current limit built into the PSU? My ...
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1answer
102 views

How to determine DC input voltage of a device without its charger? [closed]

Had a MotoMaster (Canadian Tire) 27/3 LED flashlight for 4 years now. Model was discontinued 2-3 years ago. Lost the charger at least 2 years ago and the light's battery FINALLY died today (!!) I ...
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1answer
86 views

Relation between Amps and Thickness of wires

I have some questions that have been bugging me for the past few days, and I am here in hope of some help. My Understanding of how battery works: "The battery (say 9V DC) does not store charge, it ...
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1answer
131 views

Why build very similar diesel-electric engines in both AC and DC traction versions?

I'm reading Wikipedia on GE Evolution Series diesel-electric engines. The series includes ES44AC and ES44DC models. Looks like they are very similar but one uses AC traction and another uses DC ...