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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What are the differences between an AC and DC coil relay?

If a DC coil was just a coil, it would saturate. If an AC coil was just a coil, the magnetic field would drop to zero at 120 Hz and the relay would chatter. Presumably the designs in some way prevent ...
2
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1answer
73 views

-48VDC battery bank?

I was going over a request for a solar battery charger, and one of the points was a Low Voltage alarm (possibly meaning a LVD) to be triggered at -48VDC. This is a bit confusing as, to the best of my ...
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0answers
35 views

How does buffer prevent loading effect?

Buffer is said to be used for impedance matching and preventing high flow of current.But how does it prevent Loading effect?How does usage of buffer overcome the dependance of the terminal voltage ...
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2answers
51 views

Low Voltage AC Smoothing Capacitor Calculation

I have a 9V AC source which will have a max load of 100mA. I'm trying to figure the value of a smoothing capacitor with less than a 10% ripple. I don't have a scope or else I'd just try a bunch out. ...
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1answer
40 views

Good way to switch AC/DC (Rectifier) in welder

I am building a homemade welder out of microwave oven transformers. I would like to have ideally an on off switch and then an AC/DC switch or just having one switch would work too. AC 120V 60Hz ...
3
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1answer
44 views

How can you build a floating two-port VCVS?

I have a control voltage at one point in a circuit which I need to duplicate at various other points (3 or 4, if I remember correctly). I'd like to use one potentiometer to control these voltages, so ...
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1answer
16 views

adapter replacement for 12V 0.5A [closed]

Can I use a 12V DC 1.0A adapter in place of a 12V DC 0.5A adapter for my piano keyboard? The keyboard comes with a 12V DC 0.5A adapter but it is lost. I found a 12V 1.0A and wanted to know if it can ...
3
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3answers
76 views

Long 24V DC cable not working

We have a really weird issue which we just cannot get our head around. In high level: We have a unit which contains some electronics, we can access it with 4 cables 2 for power and 2 for ...
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0answers
41 views

High pass filter DC blocking equations

Given a 12 volt DC supply to a potential divider circuit and a coupling capacitor connected to a 40 mVp AC, how would I confirm that the resistance between ground and capacitor is low or high enough ...
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1answer
97 views

How to easily get -10V and 170V

I have just managed to control an old LCD of type TLX-1013-E0 using an arduino. I would now like to use it for a project. But it needs -10V for the contrast and 170V for the background lighting. ...
0
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1answer
39 views

calculation for the response of fourth order transfer function from step input

I need some help to verify my calculation. Following is the transfer function of a control circuit $$H(s)=\dfrac{1+0.145s+0.0019s^2}{1+\dfrac{0.8}{150 ...
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2answers
52 views

Driving a large, noisy, free-wheeling DC motor (cooling fan)

I have an automotive cooling fan which is nominally 12v and draws about 15-25A with a BIG inductive spike at startup (will happily blow a 30A fuse). These are traditionally wired via standard ...
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2answers
84 views

why do rectified voltage boosts after adding a capacitor?

So I found this 9V 1A AC power supply laying around and decided to make a DC source. I rectified and added a capacitor to make things a bit even. After adding a capacitor my voltage boosted from 9V ...
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1answer
121 views

Instantaneous DC output using Laplace transform

I am testing a feedback system in which a feedback signal from sensor is applied to a correction network and then compared with threshold values. I need some clue on how to get around this task, I ...
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0answers
29 views

Converting 12V DC to 7.4V DC [duplicate]

What i'm trying to do I would like to power my DSLR Camera using an external PSU PSU - 12V DC - 21A Camera's battery - ...
3
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2answers
793 views

RF Energy Harvesting

Why can energy invested in RF radiation not be harvested fully? What are the main factors that affect this? Is there any significant research nowadays that fully describes this process? I stand on the ...
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2answers
59 views

What would be the results of two bridge rectifiers in series?

What would be the side-effects of placing two bridge rectifiers in series? The question stems from reading how some devices are manufactured with a bridge at the input to make reverse polarity ...
0
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1answer
67 views

Adding two DC Power

If I add two different DC voltage(from different source) in same line i.e 1# 100V 1A and 2# 50V 5A. So can I get output as 150V 5A when I connect both in series ? If there is any other alternative so ...
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3answers
64 views

Is it possible to change direction of DC motor using a 3-state rocker switch?

I have a 3-state switch, It has 3 pins. It can have 3 state as you can see in the picture below. when it's off (i.e on O) the middle pin is not connected to anything. When it's on I, the middle pin is ...
2
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2answers
87 views

Why are these independent loops?

According to my textbook, abca with 2 ohm resistor is independent. A second loop with 3 ohm resistor and the current source is independent. The third loop, with 2 ohm resistor in parallel with 3 ohm ...
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0answers
26 views

Pros & cons of fixed resistor variable VDC bench supply/Op Amp voltage followers?

Any opinions on the pros and cons/virtues and defects of making a simple DC bench power supply using fixed resistors and a standard linear voltage regulator, with a MOSFET around the regulator to ...
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1answer
35 views

My robot's motor has begun to spin slower, but it works perfectly if I use a different adapter with more voltage.. what does it mean?

I have the iRobot, a ping pong throwing robot. I've used it for years without any issues. At one point, my cats chewed out the original AC Adapter but luckily I had another one on hand from another ...
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2answers
52 views

How does one determine the voltage of a node?

This sounds like a very straightforward question, and probably has an obvious answer. I've read a section in a physics book on electricity, I've read a textbook on DC and this simple concept seems to ...
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2answers
83 views

Why is there continuity between the leads of my DC power supply?

I have a power supply that outputs constant 5v DC power. It's not adjustable or anything fancy. Using a multimeter, I found that there is continuity between the 2 output leads. Is this a bad thing? If ...
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1answer
57 views

How do I calculate voltage on a multi-powered DC circuit where all ends go to ground?

I'm writing software that will calculate the correct voltage on each component, given the state that the DC system is currently in (ex. what power sources are on, what relays are open, fuses popped, ...
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1answer
49 views

RD-ZD-25F, 220V/50W motor as a generator

I have 2 RD-ZD-25F, 220V/50W DC motors from 2 broken bread-making machines. Can they be used as a generator? I gave one with the hand few spins and I got a little bit of a shock from it. Thanks PS: ...
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0answers
34 views

How to determine motor's pinout

So I've savaged an old Maxon DC motor. I've searched thoroughly for some documantion but found none. So I have 6 pins which I guess should be: V+ V- Vcc GND A B Is there a way to determine which is ...
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1answer
53 views

PC fan DC adapter power requirement? [duplicate]

I just bought a 120mm deep cool fan with a rating of 12v, 0.07A (70 mA)= 0.84watts Currently I only have a 12v 2.5A (2500mA) DC adapter. I'm a complete noob in electricals...so the question is- Can ...
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1answer
51 views

DC batteries connected to multiple-core transformer

My understanding of transformers is that they take in and give out AC signals. However, the UPS system below has its DC batteries connected to a transformer. Is it possible to know the rational ...
0
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1answer
49 views

Calculating DC power usage

I am just wondering what voltage to use in this situation when calculating the power consumption of a circuit. (P=VI) I have a 24V DC power supply with 2 x 3V DC motors in the circuit. I have ...
0
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3answers
116 views

What is this on power supply unit?

I need to power a large 180W LED lamp that runs on DC so I got this transformer that is 12v × 15amp. But I don't understand the labeling on the terminals. There are 2 +V terminals but no -V ...
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2answers
79 views

I require a more comprehensive explanation of the function of zener diodes

I would first like to establish that I am simply the most basic of beginners in the realm of electrical engineering, and that complex terminology will only cause me to ask more questions. A circuit ...
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4answers
124 views

Does USB always supply 5.0V

I was wondering about this part of a circuit diagram. I believe the component marked as JP12 is a DC barrel connector, which I thought had three pins. One to detect input, one with V+ and one with ...
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1answer
69 views

Does order matter when it comes to AC power? [closed]

Is there anything about electricity or the electrical design of AC power strips that dictates in what order the devices should be plugged in? When I say, "in what order", I am referring to the ...
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1answer
49 views

Is there a rightside up when plugging in an AC to DC power converter? [closed]

When plugging an AC to DC converter into an AC outlet, does it make any difference at all if the wall wort is "upside down" or "rightside up"? Is there anything about the electrical design that would ...
0
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2answers
77 views

Very High speed response AC coupling

my goal is to achieve a HIGH SPEED RESPONSE AC COUPLING, as I want to totally get rid of the DC component even though its changing rapidly I have a signal coming from a sensor ( a proximity probe), ...
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2answers
67 views

Wiring up a AAA power toy to Pinball lighting supply

I'm trying to wire up a toy powered by AAA batteries (3vdc @ .09A) to the lighting circuit on a pinball machine (6vac @ 4A) and I was wondering what the best possible solution that I can keep small. I ...
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votes
1answer
47 views

How to controlle a motor with arduino

I have 2 og those 12v motor and a 12v battery http://www.enigmaindustries.com/Motors/Bosch_EV_Warrior.htm I want to know what s the best solution to controle the motor with an arduino Uno. Is the ...
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2answers
58 views

How do I reduce the Counter EMF?

I hope I can explain what I am asking. We will connect a DC motor to a single phase rectifier. Motor will carry a load. And motor sould be able to spin right and left. And when it is changing its ...
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2answers
47 views

Close loop circuit vs an open one in regards to an electrical bicycle light system

From what I know about DC current, for it to flow you need 2 points with different voltage (while AC doesn't flow from point to point), this why DC batteries discharge overtime, when not used, because ...
0
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1answer
50 views

Thevenin equivalent of simple circuit

I'm stuck on a problem and I don't know how to proceed. I have a circuit that consists of a 10μF capacitor connected in series with a variable resistor (100kΩ, 200kΩ, 300kΩ). I'm supposed to draw the ...
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1answer
53 views

LED DC Voltage Level Indicator

I am wanting an at a glance indicator of what voltage level is being supplied by a DC generator (think pedal power). My general thought is a series of LEDs that light up in sequence as the input ...
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vote
2answers
47 views

Is it possible to have a charging unit and output unit connected to a battery at the same time?

I am very new to DIY and electronics stuff, so please excuse myself having little knowledge about this stuff. Here is what I am trying to do: Assuming I have both things (The Converter with USB ...
0
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1answer
66 views

DC Motor circuit polarised 2 directions switches

I'm totally new to electronicS and do not understand a lot and I've read other posts but people seem to be asking different things to me so apologies in advance if this has been covered but I've typed ...
0
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3answers
49 views

DC circuit theory: Equivalent resistance help

In the given DC circuit, I need to calculate resistance \$R_{2}\$: if the equivalent resistance between nodes 1 and 2 is \$R_{e}=100 ohm\$ I get the value \$R_{2}=36.36ohm\$ \$R_{1}\$ and ...
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1answer
40 views

controllable and accurate static charge generator

ive been doing some research on methods to generated static charge. ive come across 3 main methods: wimshurst generator, van der graaf (and Negative Ion Generator). wimshurst and van der graf seem ...
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4answers
414 views

How to know exact Decoupling Capacitor values for supply voltages?

When designing circuits using various components such as IC's a lot of the time the data sheets give you an example schematic where they will usually give you some values for decoupling Capacitors. I ...
0
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1answer
33 views

AC alternative for DC diode short-circuit protection

I have two sensors (represented in the schematic below by a switch) connected to a light. If one of the sensors trips, I would like the light to switch on. The sensors and light are directly on AC, ...
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3answers
54 views

CLL(Capacitor long life)capacitor filtering to reduce the current spikes

if we are using capacitor between the coomutation segments of brush dc moto then it reduces spark generation. as main function of commutation system is to reverse the current in the coil. by using ...
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0answers
39 views

How does Mean Well LDD range DC-DC constant current drivers handle dimming?

Mean Well LDD range DC-DC, constant current buck drivers have dimming function. 5v PWM signal allows you to dim the LEDs. Without PWM, you get the full rated current output. Now knowing anything ...