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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Estimate current through inductor in DC circuit with PWM control

I am designing a circuit to control an electromagnet (coil with iron core) through a N-channel MOSFET driven by a PWM signal. I can't figure out how to derive the relationship between the PWM duty ...
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2answers
32 views

Charging li-ion batteries with protection circuit

If i'm using a protection circuit like this one: http://www.batteryspace.com/pcbfor148vli-ionbatterypack5alimitwithfuelguagesocket.aspx and 4, 3.7v li-ion batteries. Can I use a simple 16.8v dc ...
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1answer
62 views

Unable to Power Arduino and DC Motors via 2 AAA Batteries

I am using 3.7 V 2000mah battery. I am stepping it up to power an arduino board via an NCP1402. It has a continuous output current of 200mA. I am trying to run two Micro Metal Gear motors with stall ...
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63 views

How can a circuit output have voltage, but no power?

I am building a triac/diac circuit for a motor. Currently, I am testing it with only 16V AC to see if it works. I don't want to risk electrocution. I am encountering a problem where the output voltage ...
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2answers
93 views

Options for 12v battery pack with charger

I have an amp that requires 12-20v dc power. I'm looking into a solution for a portable battery pack that I can charge while running the amp as well with discharge and overcharge protection. This is ...
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4answers
104 views

Whats the point in conserving electricity if the AC current produced cannot be stored?

If we cannot save the ac current produced in a battery or some device like the DC current there is no point in conserving it because current once produced should be consumed somehow!! My faculty said ...
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0answers
45 views

Selecting motor for a DIY wheelchair stairlift

I need to make an wheelchair stairlifter for my stroked mother similar to : So I need to find out one motor in range of 200 Wat for lifting a 200KG load in slope of 43 degree from these options: ...
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1answer
72 views

Over heating H-bridge MOSFET (irf9540)? [closed]

I have done the circuit in the picture : from here (modified Question): So two LEFT MOSFET (IRF9540 & IRF540) will be overcharged and so heating and DC motor speed is Constance and don't ...
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2answers
78 views

Latching solenoid control

I am working on a personal project that will involve driving a latching 9V/DC solenoid from an arduino. The circuit I've come up with is dependent on two things, that I haven't quite figured out yet: ...
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0answers
58 views

DC-circuit with N-JFET transistor

My task is to decide RD and RS in this circuit: The properties of the N-JFET are Up = -3.5V and IDSS = 10mA. The criteria here is that the operating point should give UDS = 7V and ID = 5 mA. With ...
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1answer
80 views

DC Power supply Jack connector pinout

I'm trying to make a footprint for this connector: But I have a trouble about pinout. What is the SLEEVE TERMINAL, TIP TERMINAL, SHUNT TERMINAL? What is my power connection? V+ and GND?
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3answers
39 views

Switch 15V source with a MOS by digital 0/5V (dc)

I'm trying to switch on and off some 15V devices from Arduino Uno digital ports (0/5V). Each port must control a group of resistive loads (lights) of a train model. There are about 10 groups of loads, ...
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2answers
243 views

Filtering DC offset of a pulse train

How can I filter a DC offset of a pulse train with an RC circuit? The signal is a pulse jumping between 3.07V and 3.53V. But I need a pulse which is jumping between 0V to 0.5V. How can I filter that ...
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2answers
56 views

How to transfer electrical power from stationary to rotational part.that can be used for POV display?

I have been researching how to transfer electrical power from stationary to rotational part. Some of them showed the means by using slip spring rings like in this website ...
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2answers
75 views

AC vs DC and ELF - extremely low frequency

given : How do static fields differ from time-varying fields ? A static field does not vary over time. A direct current (DC) is an electric current flowing in one direction only. In any ...
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1answer
33 views

5v DC 1.0A micro USB device hooked to an 5v DC 2.0A charger [closed]

I've bought an Power Bank rated 5v DC 1.0A in it's input but it's extremely slow to charge via USB port, which provides an maximum of 500mA as i read in internet. I have and outlet USB phone charger ...
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0answers
72 views

Application of Fourier Series in Circuit

I am trying to find \$v_o(t)\$ in the circuit below, where $$v_s(t) = 3 - \frac{6}{\pi}\sum_{n=1}^{\infty}\frac{1}{n}\sin2\pi n t$$ The correct answer is $$v_o(t) = \frac{3}{2} - ...
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1answer
139 views

Is it safe to parallel connect components to a single to a 12v DC PSU?

Prerequisite: For a home-decor project, we wish to work with different LED strips and even a larger LED chip as a central lighting source by attaching everything to a powerful, high quality 12v CC/CV ...
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2answers
47 views

Relay - Datasheet Max DC Voltage

This may seem like a dumb question, but I want to be sure. In the below datasheet, what is the DC voltage the relay can handle? I am assuming it is the ...
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1answer
57 views

Driving a 4.5V motor with PWM from an Arduino

This is a basic question but I would appreciate help. I have: An Arduino A 4.5V DC motor Various transistors, like BC337, 2N7000, 2N2222A What I'm trying to do is very simple: control the motor ...
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3answers
60 views

Using a motor with DC

I am using a Lego DC motor with a 9V battery which can provide up to 1A of current. I called Lego support and they said the motor draws 300mA of current. What does that mean? If I plug the motor to ...
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0answers
61 views

Stacking DC-DC converters

I'm currently building a high-power LED driver to be powered from a 2.7V supercapacitor. To this end, I'm seeking a solution with high current rating (up to 3A, so ideally a controller IC rather than ...
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3answers
121 views

What happens if I supply a higher voltage than the rated voltage of my jack?

I want to replace the original jack from my notebook with a new one since it is broken (and I would like to avoid to replace it with the same as the original). The original AC adapter supplies 19V and ...
2
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1answer
67 views

Determine the maximum load of a power supply

I am trying to upcycle an old bit of tech I had lying about. The main part I am looking to recycle is the power supply however I do not have specs of the power supply itself. I have measured an output ...
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1answer
60 views

voltage sources in parallel without any resistors [duplicate]

![two dc voltage sources are in parllel & they are grounded.so what reading voltmeter will show? ][two dc voltage sources of different voltage are in parllel & they are grounded.so what ...
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1answer
89 views

Current flow in AC vs DC

If a live wire is taken from AC and connected to a bulb, while the other terminal of the bulb is connected to ground, the bulb glows; but if I take the positive terminal of a battery (DC source) ...
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2answers
166 views

How does this circuit give DC output?

I don't understand how this circuit works. I'm not sure if it's correct. It should give a DC output, but how would it do that?
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2answers
50 views

What is the difference between a 2 and a 3 solder terminals socket (coaxial jack dc)

I'm not pro with electronics and electricity and I want to replace my notebook socket so I'm looking for a coaxial jack dc socket but, as I only have two cables (a positive and a negative one) to ...
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2answers
49 views

Using 3 Channel Video Switcher Module with Arduino

Hey all I am wondering how to go about switch from camera 1, 2 or 3 using this 3 Channel Video Switcher Module on ebay here. Since there's only V+, V- and signal for the "switch" it looks to take a ...
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0answers
51 views

What AWG wire should I use to connect RGB Signal Amps to LED Strip?

I am wiring in some 5050 RGB LED strip lights in my basement. There is a small utility room adjoining and I'm keen to keep the transformers and signal amplifiers in there in order that they can be ...
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1answer
53 views

DC Motor Coil Voltage

I have a DC stepper motor that appears to be powered by 75V supply voltage (I measured this). However after connecting the motor to the controller (supply), I measured the voltage across the coil ...
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1answer
59 views

Why should I use DC coupling when I'm finding the frequency response of a circuit?

In my last electrical measurements lab I was asked to plot the frequency response of several different filters (high pass, low pass, and band pass) using an oscilloscope. My professor told the class ...
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69 views

Set ground reference of a 5v DC power supply to the middle of a 24v DC power supply

I have 2 isolated AC/DC power supplies. one generates a regulated 5 volt power supply and other generates a 24 volt power supply as you can see in the picture below: I also have designed a circuit ...
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3answers
65 views

Can I use a switch rated as 250VAC 25A to switch 50VDC 25A?

I am looking for a switch that can handle 25A continous current, the voltage will be maximum 50VDC, most often about 46VDC, and it will be used to switch on two dc-dc converters that have no load ...
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2answers
82 views

How do I drop 19VDC from a 0-60VDC source to get an accurate linear 0-48VDC signal

I've been using the Stack Exchange website for years, but never asked or answered a question, so first I'd like to say thank you for all of the help over the years. On to the problem: I want to ...
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3answers
83 views

Connecting parallel DC loads

Consider the following power supply interface. I'd like to power a number [1,N] of bitcoin miners, 12V, 5A each one. question is: do red wires must be connected with V+ pins ? do black wires must ...
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0answers
41 views

Designing a Solar Diorama with Motor and LED Indicator

I'm trying to design a Solar Diorama that uses Solar PV panels to power a small spinning motor and an LED indicator light that will show the current amount of power. Motor: 12 Volt DC, 2.1 Amps, 25.2 ...
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3answers
70 views

Low voltage adjustable DC power supply (0.1 to 0.75V DC) @ 300 mA

I need to create an adjustable DC power supply that can output between 0.1 and 0.75V DC at 300 mA (possibly as little as 100 mA). My input voltage can be anything, including +/- rail. Currently I am ...
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63 views

Stepper motor to replace brushed DC motor to be used to start a gas engine?

I'm trying to decide if it would be possible to use a stepper motor to replace a current 12V DC brushed motor that is used to turn over a small (~149cc) gas engine for starting. The reason why is, I ...
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0answers
78 views

DC current amplification

i'm trying to design a battery charger for 5Ah li-ion battery. Due to cost management problems, i am not able to use advanced 5A charger controller ICs; instead, i am going to use a 1A controller with ...
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2answers
72 views

How do we predict if power loss will increase or decrease in a DC circuit?

I want to know whether it is possible to predict if power loss will increase or decrease in a circuit with a fixed EMF, a fixed resistor in series and a variable resistor in series. If we change the ...
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1answer
23 views

Amperage for Sony SNC-VB630 Camera [closed]

I am trying to choose a right DC adapter for SNC-VB630 CCTV Camera but the only specs I could find in the official documentation was 'INPUT 12V DC'. Nothing about amperage. I have a 12V dc adapter ...
0
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0answers
72 views

PWM and brushed DC motor - AC input? Limiting RPM?

I'm looking to replace the 20-year old poorly-performing speed control in a MIG welder. It allows the user to adjust the speed of a small brushed DC motor, which drives thin welding wire of of a ...
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0answers
67 views

Calculate current in an series RC circuit with a DC square wave source?

Am still a noob in electronics so bare with me, In the image bellow how is the voltage drops found and the current in the meters, what is the formula? and if instead of a capacitor an inductor is used ...
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1answer
41 views

Electronics by Example [closed]

I am interested in learning more about electronics. I know some basics about resistors, capacitors, transistors, and diodes. I would like to learn more about things such as operational amplifiers, ...
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1answer
39 views

Voltage wave form across a DC motor driven by a transistor with pwm

Above is the simple implementation for a DC motor control with pwm. I was expecting to see a square wave with a Vmax when Q1 is ON and zero when Q1 is OFF like the one here: standard pwm But ...
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1answer
92 views

Measuring Current in 12V DC Fan

I am trying to measure the current of a DC computer cooling fan (Intel E18764-001) at various volts. Its rated specs are: 12V 0.20A. Check it out here. So I am suspecting that this is telling me: ...
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1answer
126 views

Calculation of base current resistor resistance for a transistor operating in switch mode? [duplicate]

I have a 9V DC motor and I want to control its speed with an Arduino board with help of a power transistor TIP120. In one of the web-tutorials the writer explains how to calculate the resistor ...
2
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3answers
200 views

What is the advantage of a switching over a linear power supply?

I want to build my own switching power supply. I already know how to make a 10 Ampere Linear supply, and I'm wondering if I should bother. What do I have to learn to do a switching supply? What makes ...
10
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3answers
584 views

Locking up a DC motor with constant supply a bad thing?

I am working on a little pen plotter project and for one of my motors (which supports the pen) I have used a small DC motor obtained from an old DVD drive. I have noticed that if I supply a constant ...