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

0
votes
2answers
36 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 ...
0
votes
3answers
131 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 ...
0
votes
1answer
41 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 = ...
1
vote
0answers
76 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: ...
0
votes
2answers
38 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
votes
2answers
67 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 ...
1
vote
1answer
55 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, ...
1
vote
2answers
51 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 ...
0
votes
4answers
85 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 ...
0
votes
3answers
97 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 ...
1
vote
2answers
54 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 ...
1
vote
1answer
42 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 ...
1
vote
2answers
42 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
votes
1answer
27 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
votes
5answers
784 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 ...
0
votes
2answers
25 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, ...
0
votes
1answer
46 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
votes
4answers
71 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
votes
1answer
30 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
votes
1answer
107 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
votes
2answers
64 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, ...
1
vote
2answers
81 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 ...
-6
votes
1answer
101 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
votes
1answer
25 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 ...
0
votes
2answers
41 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
votes
1answer
61 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). ...
0
votes
1answer
42 views

Switching circuit or relay [closed]

I'm new here and don't know much more about electronics.I need a switch/relay that help me off DC line when AC (grid) line is available and automatically turn on when AC (grid) line is not available. ...
0
votes
3answers
86 views

Outputting 2 different voltage with one power supply

I'm wondering if it is possible to output 2 different voltage with one power supply (a 3.7V Li-Poly Battery) by placing 2 DC Boost converter in parallel? The schematic is as shown:
0
votes
1answer
41 views

Electrical Braking: Why does voltage decrease with a decreased rheostatic load?

So I've been messing around with DC motors and electrical braking. BY placing a variable resistor across the motor terminals of the motor I've been able to vary the braking effect and observe the ...
0
votes
1answer
25 views

Re-attaching Tablet Lithium Ion Battery With DC Power Pigtails

Complete electrical newbie here. Please forgive my ignorance. I have a tablet that gets "circuit locked" or something. It refuses to detect the charged battery. It seems to charge the battery, but ...
1
vote
1answer
25 views

reducing input voltage to motor

I have a hypothetical question about running a DC motor on lower voltage than it is designed for. Lets say I have a 2hp 100VDC (yes, Direct Current) motor that I want run on 12 VDC. The motor is 2hp ...
-2
votes
1answer
49 views

450mA in CK1050 rotary switch

So i bought CK1050 rotary switch i now i realized that it's rated only for 150mA 250V AC/DC on the data sheet. I need to use it with 12V DC at 450mA so will it be safe? If you think the watts it ...
-2
votes
1answer
40 views

A superposition theorem question

simulate this circuit – Schematic created using CircuitLab I have a problem from the image. According to superposition theory, I tried to find total resistance of V2 source in order to ...
0
votes
2answers
56 views

Blocking DC when driving a buzzer with a PWM signal

I am driving a piezo buzzer with a PWM signal (typical freq. 100Hz-1kHz) in order to generate 'beeps'. However due to software constrains (*), when the PWM signal is stopped I can't control if it ...
0
votes
1answer
34 views

Capacitor Sizing for A Full Wave Bridge Rectifier?

Building my understanding of the issue from (First PSU - need help with capacitor size) (especially the comments/ripple wiki/several capacitor sizing webpages) the calculation for rectifying a full ...
2
votes
3answers
324 views

What does RU (UR) label on DC power relays mean?

I'm trying to figure out what does RU or maybe UR label mean on the body of many many relays. It's labeled almost on all (I've seen so far) DC relays which make me very curious :). Any suggestions?
0
votes
1answer
37 views

Low RPM, Low Power, Low Torque Motor (to be solar powered)

I am trying to build a small contraption/artwork to be mounted on a wall indoors. Ideally it will solely solar powered from a small solar panel (10cmx10cm). It needs to spin slowly anywhere between ...
0
votes
0answers
64 views

Software Controlled DC Power Supply

A scientific apparatus has to be air-cooled to a defined temperature. Software side with PID etc is solved. We need to control two DC brushless fans in a way they run smoothly. If we just use PWM to ...
4
votes
2answers
628 views

Are we close to a pure DC (or hybrid) household? [closed]

This is a philosophical question. Over the last few years, many of the household devices, particularly those that are more mobile and etc are DC devices. Are we at some point where a DC household may ...
0
votes
2answers
55 views

Can I use a USB connector/plug for RGB Led Strip

So I have an RGB Led Strip that requires power (3 Colours and the ground). In total it draws about 1A @ 12V = 12W. Could a USB socket be used to handle this? Otherwise I'm simply seeking a neat and ...
0
votes
4answers
76 views

Converting a toy from battery to DC power adapter

My kid's bubble blowing machine runs on 8 AA batteries which it chews through in less than an hour. Also, only the first 15 minutes seem to make a satisfying amount of bubbles and after that, it fades ...
1
vote
2answers
155 views

Tactics for Controlling Heat in a High Current Bridge Rectifier?

I'm having trouble controlling the heat from running a bridge rectifier (Similar to ...
0
votes
1answer
30 views

Run CB Radio from AUX power [closed]

Sorry if this isn't the right place for this. I have a Uniden UH015SX (https://www.uniden.com.au/resources_main/pdfs/uh015sx_OM_2yrWarranty-Updated.pdf) which requires 13.8v of DC power, but I'd ...
0
votes
1answer
84 views

How many pairs of wire to use for Power over Ethernet?

I have a custom setup to supply power over Ethernet cables. I used a pair to connect to a telephone and another pair for power. The device needs 12 Volts at 0.5Amps to run. In normal setups, which ...
0
votes
1answer
63 views

Lowering the voltage range of a variable DC bench power supply

I've been shopping for components to build a bench-top DC power supply, much like the one built in Great Scott's video. I'm planning on using a LTC3780, which has an output voltage range around ...
1
vote
3answers
84 views

555 high amperage charge pump inductorless voltage doubler

There's a few resources out there for indcutorless boost circuits, or charge-pump voltage doublers and triplers. http://www.electroschematics.com/648/555-voltage-doubler/ But this circuit is only ...
3
votes
2answers
175 views

Differences Between Smoothed DC & Not Smoothed DC With Respect to Heating

Are there any significant differences with respect to heat generation of a bridge rectified circuit with smoothed DC by use of a capacitor vs one that just uses the raw absolute value of the sine ...
12
votes
5answers
1k views

Anything special to consider when running a 12v “Bus” throughout my house?

I've recently begun playing a lot with tiny programmable computers/controllers (like the Raspberry Pi and the Arduino), and I'm planning to distribute several throughout my house as various sensors. ...
1
vote
2answers
59 views

Electrical current characteristics through conductor

This is a strange theoretical question, and I won't even begin to try to explain what train of thought has led me to ask the EEs... When electricity travels through a conductor, let's use the obvious ...
0
votes
1answer
124 views

Can I give DC 12V to a AC 12V input?

I have a circuit that takes 12V AC as an input but my bench power supply only delivers 12V DC, is there any issue if I give the device DC instead of AC? (Same voltage) Straight after the input there ...