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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AC to DC wall adapter circuit

I'm trying to design an ac to dc conveter (230V ac to 12V dc). Haven't decided on the current yet. It's likely to be around 2A. I want the circuit to be compact and hence I think it is best to follow ...
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40 views

Current across high speed mechanical switch contact even if it can’t be measured?

If I am cycling a mechanical switch at a frequency higher than the bandwidth of a current amplifier and biased using a DC source, is current actually flowing across the contact? The following ...
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37 views

How to build 5W LED bulb circuit from 230V 50Hz main AC supply with and without Transformers? [on hold]

Please answer with circuit diagram with all values or give me the link.Tell me the efficiency also. Thank u...
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1-2kW solar voltage regulator cca 28.9V to 24V DC stable [closed]

I've got several solar panels simillar to these http://www.solardesigntool.com/components/module-panel-solar/BP/984/BP3220T/specification-data-sheet.html Each panel is rated 28.9V 7.26A (max 210W) ...
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0answers
34 views

Obtain plugs for DC connections? [closed]

Where can I get plugs for DC connectors? For example, if I want to make a modified power supply for DELL laptop I need to get a plug that fits their distinctive 8mm form factor. How can I get those ...
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3answers
40 views

Voice Coil/ Solenoid driver

I am trying to figure out how to drive a solenoid/voice coil at 3V and 400-1000mA with a reciprocating output (forwards and reverse current) at around 50Hz as cheaply as possible. I have built some ...
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2answers
71 views

Resistance of electronic circuits

I am currently trying to build a Regulated DC Power Supply for an electronic piano. I am trying to find the minimum capacitance that I need to able to reach the desired ripple voltage. To find my ...
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1answer
34 views

Direction and Speed control using same throttle

I have a 24VDC permanent magnet motor such as those commonly found on a mobility scooter. I would like to be able to control both the speed and the direction of the motor with the same throttle ...
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2answers
58 views

Can I power two linear DC regulators, each running a motor, from a single 12v source?

simulate this circuit – Schematic created using CircuitLab I am building a twin air pump for a pond, powered by a 50W PV system with charge controller connected to a DIY fused DC consumer unit. ...
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3answers
89 views

Does a helicopter battery drain when it is “off” but attached to a battery hot bus?

I'm reading about the DC Power System for a civilian helicopter. It shows the following diagram for when the battery is off: However, it shows that the ...
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1answer
93 views

Switching on and off high 50V DC circuit?

I'm having a little trouble finding a way to activate my circuit. I don't have a proper circuit drawing tool available however hopefully my drawing from MS Paint will do. //////////////////////////...
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4answers
533 views

Why is an infinitely large capacitor a DC open circuit?

This really sounds like a stupid question, but I believe it's worth asking: Due to \$I=C\frac{dU}{dt}\$, and \$C\$ is infinitely large, any minor change in \$U\$ would result in infinite ...
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1answer
45 views

Battery Charger From DC Motor

So long story short I'm attempting to build a charger for batteries using a DC motor. The batteries I'm planning on charging are old smartphone batteries at 3.7V and 1000mAh. The DC motor that I am ...
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1answer
51 views

DC barrel jack datasheet dimensions!

I am using pj-102ah dc barrel jack. I am not sure if this is a mistake in the dimensions, or you can correct me if I am wrong. the top left red circle shows the the length of the three pins which is ...
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1answer
60 views

What is the correct way to add a direct voltage and an alternating voltage

Below I have two schematics that add two voltages (one direct, one alternating). Added to that, the both the AC and DC signals are going through voltage divider, but that isn't important. I'm ...
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2answers
56 views

why commutator requires so many slots

At a given point of time, current in any wire in armature winding is either positive or in negative direction, then why there is a need of so many slots in commutator? doesn't a two slot commutator ...
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3answers
51 views

DC rating for specific AC rated relay

I am interested in buying a high amperage relay which is AC rated (https://www.panasonic-electric-works.com/cps/rde/xbcr/pew_eu_en/ds_61A04_en_dqm.pdf). In particular it is rated for 60A @ 240VAC and ...
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2answers
86 views

DC circuit schematic has both positive and negative supply as well as ground?

I am trying to breadboard a DC circuit schematic (a sawtooth voltage controlled oscillator, to be precise). In the schematic there is a positive supply, a negative supply and ground (+4.5V, -4.5V and ...
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0answers
36 views

How best to convert 47V/3A solar source to 5 V 0.5 A output for USB?

What's the best way to charge a USB battery pack (5 V, 0.5 A) from a 47 V, 3 A solar panel? Just a simple PWM or MPPT charge controller?
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37 views

How can I calculate the coefficient viscous friction of brush-less DC motor? [closed]

I want to use this equation to simulate the torque produced by brush less Dc motor: \$T=J*\frac{\delta \omega(t)}{\delta t}+b\omega+c*sign(\omega)\$. And I need a theoretical formula to calculate b ...
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1answer
40 views

Ethernet device voltage protection

I am designing a system with multiple remote devices connected to a central hub, supplying low voltage DC power and RS-422 data. I plan on using RJ45 connectors, and am wondering if ethernet devices ...
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1answer
106 views

Plugging in USB device shorts out USB hub

My device is 12V DC and takes a maximum to 1.08 Amps. The cable is split where one end goes into power and the other end goes into USB. Works: Plug device power into 120V AC adapter which converts ...
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2answers
261 views

Multimeter reading 0 and drawing too much from DC power supply

So I've got a circuit that requires both 5V and 3.3V so I bought a 5V 2A AC/DC converter from a store, which I will add resistors to later for the 3.3V. Before I connect it to my circuit, I wanted to ...
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2answers
179 views

How does television EHT Transformer (that connected to anode) operates in DC?

A step-up transformer takes AC input and gives AC output. Then, how does the E.H.T (Extra high-tension transformer) create 18 KiloVolt or more, DC-output on the CRT (enough to shot the electrons on ...
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72 views

How to construct a DC Home Supply System

So I've been thinking hard of how to construct a DC socket to use in combo with a solar setup at home so as to cut losses in using inverter plus DC appliances seem to be generally more power efficient....
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44 views

LTspice 101: Strange values with DC operating point

Just started using LTspice and I'm struggling with what is probably a total newbie mistake on a DC operating point test. Created a basic circuit, 10V voltage source and 1k resistor in series, and I'm ...
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0answers
8 views

Can I use a Revolectrix Power Lab Cell Pro 6 to power XB1?

I had a quick question, wondering if it would be possible to use my Power Lab Cell Pro 6 battery workstation to rig up a power source for a MS Xbox 1? Similar to this question, but different power ...
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2answers
101 views

Do longer wires consume more power?

In DC, for example at 12V, will a longer power wire (lets say 10 meters vs 10 centimeters) cause a high current consumption?
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1answer
115 views

A question on PWM frequency of a DC motor

I'm planning to pwm-control four of the following motors by a single ArduinoUno: http://uk.rs-online.com/web/p/axial-fans/8179151/ For some reason the nearest pwm frequency I can set is 31kHz. The ...
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2answers
62 views

connecting a hp laptop charger adapter three wire output to a two wire cable [closed]

My laptop charger adapter broke and I a have this other old adaptor in the house. They both have the same voltage(19V) and 1.58A. The first adapter(The one that broke) has three wires (black, white, ...
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2answers
67 views

Use of 230VAC overcurrent protection for 24VDC circuits [closed]

Is it right to use 230VAC overcurrent protection for 24VDC circuits? Why? Why not? For example: http://www.tme.eu/en/details/a9f05120/circuit-breakers/schneider-electric/ I saw some machines which ...
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1answer
46 views

Help wiring DC motor

first post here. I'm wiring a DC motor and horn that will go into a small boat I built. I would like to get some help to see if I'm doing this correctly. -DC motor hooked to a 12v battery (Max draw ...
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43 views

Am I correctly concluding that these two AC/DC adapters are interchangeable [duplicate]

I'm in the US with 120V mains. I have a "heavy" style AC/DC adapter (weighs a pound or so) and a lighter one (weighs a couple of ounces) which came off a 1TB Seagate NAS. Can I replace the heavy one ...
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37 views

Potentiometer controlled current regulation

new one here. Thing is this; I have an electromagnet (or a solenoid as I prefer to call it). When it gets energized the plunger inside is pushed out to a certain length (goes back to its original ...
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2answers
91 views

wirelessly remote-controlled DC power supply with variable voltage

I need a remote-controlled (wireless) power supply, outputting between 0 and 10 volts and 0 and 2 amps, preferably DC. It should take 110v/120v AC as input. Its voltage should be controllable with a ...
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48 views

Current in Buck Converter

In Buck Converter, when switch in ON, Vi(I/P voltage)=Vl(inductor Voltage)+Vo(O/P voltage)when we switch it On, current increases linearly(according to the wikipedia) then Vl=Ldi/dt=constant and Vo(=...
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2answers
102 views

How to fade or delay a DC Signal to remove speaker “thump”/“click”/“pop” from transistor switch?

I'm trying to create a digital audio switch or relay using an Arduino nano. It's a very simple circuit, it's just a gate (transistor) which is operated by a digital signal (computer) through a ...
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1answer
72 views

Is the resistance in a DC Motor constant if the voltage is?

Is resistance in a DC motor constant if both the load and voltage are constant as well?
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70 views

General question about Capacitor sizes in DC circuits

A general question -- let's say there is a DC circuit with a capacitor that needs to be replaced. Can I use any capacitor that is at least as large or do I have to use one that is exactly like the ...
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2answers
100 views

Using a multimeter to see if ground is connected

I've been diagnosing a problem with a relay on my car. One of the pins in the socket that the relay goes into controls the ground for the throw of the relay. When the car's computer wants the relay ...
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4answers
118 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
74 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
68 views

Ground my body to DC (USB) [closed]

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
77 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
70 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
95 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
68 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 ...
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1answer
23 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 22....
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1answer
55 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 ...
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2answers
91 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 ...