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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51 views

Motor control using potentiometer characteristics

I am trying to control a dc motor using potentiometer(armature control). Increase in voltage leads to increase in speed of motor. Even though this seems in accordance with general understanding, but i ...
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1answer
60 views

If a load is placed onto a DC motor, will the current increase? [duplicate]

When a load, such as a weight on string, is placed into a motors axle, will this cause the current to increase?
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1answer
56 views

Ground my body to DC (USB) [on hold]

Does grounding body to DC power source makes sense, to get rid of any electrostatic(?) charges from my skin/body ? In my new house, when I'm standing on the floor, connect voltage meter (AC) and ...
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1answer
36 views

Light simplification [on hold]

I am working on lifi implementation. I have a question regarding this perspective. How can a video signal that is incident on a photovoltaic cell be converted back to dc( video) signal?
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1answer
65 views

Using an AC drill motor with DC?

I have this motor from drill that is powered from AC. Is possible to use the motor with DC current?
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1answer
61 views

Understanding AC to DC conversion

I am able to see following specs on my laptop adaptor. 65 W Input AC: 100 - 240 V, ~1.5 A, 50 - 60 Hz Output DC: 19.5 V, 3.34 A My HP laptop: I am bit unclear ...
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2answers
81 views

Can I connect pin 11 of TL084 to ground? I mean, are there the consequences?

I wonder if it is possible to connect pin 11 of a TL084 to ground to avoid having two sources. I need to compare two signals: Signal 1: This is a DC 9V source. (this goes to + terminal of Opamp) ...
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1answer
46 views

ACS712 Low Current Sensor

Before I begin, just to let you know that I'm new to electrical engineering, in case that my question sound weird to you, but here's my problem. I bought few days ago ACS712 Low Current Sensor and ...
0
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1answer
21 views

DC consumption translation to AC consumption

I've a battery charger that can output 9v and 2.5A and I use full power from it that is 22.5W. Can I translate this power consumption from DC to AC current? My AC is 220V 50Hz, so I'll consume ...
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1answer
48 views

DC Bus for Solar Charge Controller Battery

I am just learning the set up for a back up power. I am just wondering whether the DC output from the charge controller or the battery can be used for multiple loads. For example, I want to power my ...
3
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2answers
70 views

Small DC motor Heating up!

I am just trying to build a small fan to keep my Mac a little cooler from outside. So I have this little Box Design I made. Now, I'm a total noob at this thing so I need beginner level help here. I've ...
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1answer
43 views

Multiple DC Voltage sources in parallel

I'm building an alarm system (paradox EVO192 with ZX8 extension modules) and was hoping to have separate sections of the system each powered by it's own battery backed up power supply (something like ...
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2answers
85 views

Connecting a battery powered circuit to the earh ground [closed]

In the following circuit what would be the effect of tying a circuit to the ground from the -2V rail ? I know that no current would flow to the ground since there is no closed loop formed, but ...
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2answers
41 views

Electric latch for math toys

Please fix my tags. I'm making a series of interactive puzzles for use in classrooms. One of them is an equation graphing. It will have a grid of screws stuck into wood, with the axis drawn on. ...
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0answers
13 views

Main to 12v adaptor to power motor [duplicate]

What adaptor should I use to run a 12V DC High torque motor (60 RPM) on the mains (240V)? Thanks for your help Salomé
0
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1answer
46 views

Bridge circuit and the error caused by a differential amplifier

I am currently struggeling with solving the following problem: The circuit below shows a bridge circuit, where the differential voltage between the branches is measured by a differential amplifier. I ...
0
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1answer
41 views

Control USB powered light with PWM, would it work?

A few weeks ago, I asked about controlling a DC powered LED lamp using PWM here, I was told that if I can get a LED lamp that uses an external DC adapter to power up, I can use a MOSFET and control it ...
0
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1answer
64 views

Op-amp voltage divider

I have troubles understanding the way the circuit below is solved. I figured out that the solution is: $$ V_+=\frac{R_2}{R_1+R_2}V_1 \\ V_a=\frac{R_3+R_4}{R_4}V_+ $$ But what is actually the reason ...
12
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5answers
4k views

Why are DC signals bad for loud speakers?

I googled and found out through some forum that: DC has a constant amplitude which overheats and destroys the voice coil of the speaker. Could someone clarify if this answer is complete and ...
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1answer
44 views

connecting the negative positive terminals of two dc to dc converter

I require two voltages for my device 22 and -20 is it possible to use two dc to dc converter to generate the two voltage and connect the negative and positive output terminals, and that will be my ...
0
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1answer
74 views

Decreasing Voltage of Power Supply via voltage regulator without using input/output capacitors

I have a HP laptop power supply 18.5V/3.5A that I intend to connect directly to LM7812 or LM7805 voltage regulator when I need to drop the voltage to 12V/5V. Since the laptop power supply (which is ...
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2answers
56 views

Why is DC used in circuit devices? [duplicate]

Why do circuits mostly run on a DC current? I understand that electric motors use AC but things like my laptop operate on DC. Are there another advantages to AC current that made it the standard ...
0
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2answers
42 views

Input impedance of audio amplifier, unclear from datasheet

I have a AN7190NK audio power IC. It is a amplifier for the car radio. I want to know it's input impedance. In datasheet it states that: Input impedance ZI VIN = ± 0.3 VDC 28 kOhm I don't really ...
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3answers
153 views

Op-Amp Circuit add/subtract voltages

I am currently struggeling with the following problem. I need to find an amplifier circuit which implements the following equation: $$ U_a=U_1+2U_2-2U_3 $$ I decided to go with the circuit shown ...
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2answers
53 views

Question about multimeter resolution

So i got a multimeter from a friend for free. This is the one: Multimeter Info In the manual of the multimeter it says that the lowest resolution of DC Voltage is 0.1 mV. does that mean that i can ...
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3answers
170 views

Why can't I vary the speed of a dc motor with only a potentiometer?

I made a simple circuit with a 9 volt battery, a dc motor, and a potentiometer. The positive of the battery is connected to one side of the potentiometer and the negative to the other. One side of the ...
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1answer
52 views

How to do DC Analysis for a Common Source Biasing Circuit using NMOS

I am having a lot of trouble with this specific problem. I want to find Vg, Vd, Vs, and Id for this specific common source biasing circuit that has an NMOS. I have these values given: Vdd = 9V, k/2 = ...
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0answers
90 views

Circuit for voltage division and DC shift doesn't work

I've connected the circuit below on a breadboard and tested it in the lab: Components: ...
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2answers
42 views

finding the sinusoidal values of a complex current or voltage

I am having some trouble understanding this type of transformation. The materials provided by my professor doesn't even mention the method that is being used to switch from complex to sinusoidal and ...
2
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2answers
79 views

How “slow” is a Class T “slow blow” fuse?

I have a DC inverter that's rated for 3kw sustained with a 6kw peak (for up to 5 seconds). Per the Inverter manual, the manufacturer recommends a battery fuse rated for "at least 350 amps". How can ...
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1answer
63 views

How do I calculate Watts for a dual rail power supply?

If I have a 5V power supply powering a circuit which is connected to 0V, to calculate power usage I would take the total current in Amps and multiply by 5V. However, my current circuit uses -12V, ...
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2answers
63 views

DC Motor Speed Control Board

I have a 120VAC DC motor speed controller (diagram attached as picture) it works very well, however in the circuit there is a 5000K POTENTIOMETER that controls the actual speed/voltage - The ...
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4answers
89 views

Using a battery charger instead of a battery?

I have built a simple circuit with two diodes that light up intermittently. It requires 9V DC voltage to run. I don't have a DC source at home, and would like to avoid buying 9V batteries repeatedly ...
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3answers
113 views

Why does an uncharged capacitor short out a resistor in a basic DC circuit?

I’ve really only dealt with two laws thus far concerning circuits and capacitors: $$V=IR$$ $$Q=CV$$ The first obviously being Ohm’s law and the second the equation for a capacitor’s charge. I’ve seen ...
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2answers
60 views

DC/AC coupling in an oscilloscope

I would like to know when it's suitable to use AC coupling and when it's not in general? When using an oscilloscope, I want to know in general when it's better to use DC coupling over AC coupling ...
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1answer
60 views

Measuring DC current with Hall Effect sensor over PIC on the same circuit

Before I begin with my question just so you know I'm not very familiar with electrical engineering so please forgive if I ask some dumb question :) What I want is to know if I can use Hall Effect ...
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2answers
56 views

Permanent magnet DC motor earth wire

I have just inherited a piece of equipment that is powered by a 12V DC permanent magnet motor. My hope is to drive it using an Arduino PWM and a H-Bridge to manage the current requirements (7.3A ...
0
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1answer
28 views

AC circuit to act as a relay for another DC circuit

In this circuit, I have caused an AC current to power the gate pin of the Thyristor, which in turn should allow the 10v DC current to pass even after the AC current inverses - it is not a ...
4
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5answers
811 views

Are there any advantages to either DC barrel connector polarity?

I was putting together a fairly basic LBB at the weekend to control a handful of DC devices which got me thinking. Why are both pin-positive and pin-negative DC barrel connectors used? Are there any ...
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2answers
28 views

Wound Rotor Induction Motor Generator Conversion

I have a 3 phase wound rotor induction motor which I would like to convert into a generator. I was wondering if it is possible to excite the rotor windings using a DC current. I attempted to do this, ...
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1answer
47 views

DC Jack Adapter for 5V 2A Wall Wart

Below is a wall wart with ratings 5V 2A. I'd like to buy a DC adapter of some kind for this wall wart, so I can easily wire things to a circuit or bread board. What is the name of the DC side of ...
0
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4answers
80 views

Difference between a 'DC DC Switching Regulator' and a 'Linear Regulator'?

What's the difference between a DC DC Switching Regulator, and a Linear Regulator. I'm buying one to make a variable power supply (is this the best way to do it?) and I need to just output an ...
0
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1answer
34 views

High Torque DC Motor

I am trying to use a high torque dc motor with gears to drive a low torque dc motor but with higher rpm. Is there a relationship between the current draw of a DC motor with the torque? I have seen a ...
0
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1answer
145 views

Controlling a single phase AC fan with a 0-10V DC input

I have a fan motor which is a permanent split phase single phase capacitor motor: http://uk.rs-online.com/web/p/axial-fans/2781543/ I currently control this fan's speed with the following ...
0
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2answers
65 views

How is it physically possible that there is no voltage drop across two pins of this DC jack?

I have a DC jack with three terminals. Terminal 1 is tip (+), terminal 3 is sleeve (-), and terminal 2 is a switch, my understanding of which is such that if there is no adapter plugged into the jack, ...
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2answers
94 views

Creating a DC resistor network matrix

I have the following resistor network and I need to make a 7x7 matrix which would be the solution . I know the resistor values, but not the v1, v2, v3 or any of the current. I'm supposed to combine ...
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1answer
103 views

Do DC current can be earthed? [closed]

If I take a 12 V battery and connected its (+) terminal with the (+) wire of a load and connected the negative wire from the load to the ground (earthing). I have heard that earthing absorbs current ...
0
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1answer
26 views

Slipping in an external adapter [duplicate]

I have an Atari 1040ST with a half-bad power supply - Along with two 5v Red wires that Are good, there is a Blue wire that requires 12v .9A (aka 9mA??) - With A/c on, it's measuring at 10.73v (on the ...
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2answers
43 views

Help with DC switch current

I have a DC switch rated at 2A at 36VDC, if I were running the switch at 4VDC what would be the maximum current I could safely run through it? I'm assuming I can't simply use the wattage to calculate ...
0
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1answer
65 views

Removing ripple in DC supply

I have an AC to 18v DC, 25MA, power supply (wall wart) that is used for a guitar flanger pedal. The supply generates some ripple noise into the pedal's audio (it is not there when using batteries). ...