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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29 views

Component to measure energy transfer

Is there a component to measure energy transferred in a DC circuit? Essentially it would have to be some kind of counter and it would be incremented by the power level on every beat. I am looking for ...
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1answer
41 views

Need help with stepping down DC volts

I don't have much experience with electronics, I'm simply trying to get (at least what I think) is a fairly simple circuit running. I've got a blower fan that I need to get running. It uses 12VDC at ...
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1answer
55 views

Fail circuit with N MOSFET, what is wrong?

I have a circuit with two DC power lines coming from BATT A (1A) & BATT B (2A) (two outputs of a power bank). There is a sliding switch on the power line of BATT A. I would like to keep only one ...
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2answers
61 views

How can I detect which DC power source to send to an underwater camera housing?

I have a small problem and hoping someone can help: I am trying to design and build a reasonably universal underwater housing for some different cameras. there is a breakout box on the surface and ...
0
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1answer
32 views

Stabilize a 12V DC supply (from Lipo)

I'm newbie in electronics, but I want to learn some basics things. I have a 12V DC output (from a charging/discharging PCB Lipo battery), and I would like to stabilize it to run a mini-amplifier ...
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2answers
75 views

How to emulate a switch on power line

I have a circuit with two DC power lines coming from BAT1 (1A) & BAT2 (2A) (two outputs of a power bank). There is a sliding switch on the power line of BAT1. I would like to keep only one switch ...
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1answer
57 views

Basic microcontroller to dc motor setup [closed]

I am looking to program a microcontroller to power a dc motor at a given speed. The speed will be determined by a gyro reading of another spinning part. It will need to spin at about 4 Hz (240 rpm) ...
24
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8answers
4k views

Why does a capacitor block DC and not AC? [duplicate]

If someone can explain why a capacitor blocks DC, but not AC, with some math, I will understand all of that much better. I know that there are picture animations illustrating this, but I really want ...
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3answers
68 views

What's the easy way to measure a DC hobby motor's inductance?

When using simulations(SPICE), I need to model a DC motor or an electromagnet, relay ect. as an RL in series. I can measure the R resistance by an ohmmeter. But I couldn't find an easy way to find ...
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2answers
38 views

Voltage regulator current consmption

Our pcb current consumption is less than 0.5mA . We use a 3.7v lithium battery, and the battery goes through voltage regulator ...
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4answers
108 views

Does electrical current flow from positive to negative or negative to positive?

When you listen to people wiring up a DC circuit they seem to mumble about the electricity flowing from positive to negative. However in school I was always taught that DC electricity flowed from ...
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3answers
135 views

Why the diode has higher impact on dc characteristics than ac?

Consider this circuit which consists of a DC bias and an AC source connected with a diode and resistor: Source: Boylestad and Nashley book 11th ed. Using superposition theorem the circuit was ...
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1answer
64 views

How to wire many bi-color LEDs to a single power supply, and switch them on/off individually

My goal is to have 13 separate stations, each with a bi-color, common cathode LED (Dialight 606). These LEDs do not require external current limiting resistors. Each LED can be 'On Green', 'On Red', ...
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0answers
23 views

Modifications to Neon Sign Transformer to turn it into a variable DC power supply?

I would like to turn a neon sign transform into a DC power supply. Looking into this it would appear I need some rectifiers to turn the AC output into DC. I could use a variable resistor to adjust ...
0
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1answer
45 views

Customized Digital Clock(two power sources)

I am quite newbie in electronics. Recently I bought a Digital Alarm clock and tried to customize it by adding DC motor wheels . Idea is to set an alarm , when its alarm time apart from sound it should ...
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0answers
40 views

Single Transistor DC TO AC Circut

I have a question that may be rather difficult to ask and format however I will try. Now I am very new to electronics in general but in my spare time I play around with them a little bit. I have ...
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0answers
25 views

What is a GMT/KLM/TPM/TPA fuse panel?

I am trying to power 18 TECs with a an SMPS having adjustable voltage output (Meanwell: SPV-1500-12). The total current required by the TECs would be about 108 A at 12V DC. I was wondering as to how ...
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2answers
51 views

How to add solar DC output, Wind DC output and Fuel cell DC output to create a DC bus

How to add solar DC output, Wind DC output and Fuel cell DC output to create a DC bus. My doubt is, Is it possible to connect the outputs of different type of power sources(considering the DC voltage ...
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1answer
40 views

DC motor selection criteria for electric vehicle application?

I read that for DC electric motors you should generally use the motor with the highest "motor size constant" you can (motor size constant Km = Kt^2 / R, where Kt is motor torque constant i.e. N*m/A, ...
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2answers
161 views

Why are home appliances and other devices made to operate on dc?

Why are home appliances not designed to work on ac?why cant we just stepdown the incoming 230V and design the systems to operate at low ac voltages,instead of converting ac to dc?
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1answer
68 views

AC Wire Resistance

I stumbled across some unexpected data points when measuring the AC resistance of magnet wire. I varied the frequency of the AC voltage and measured the corresponding impedance of half a meter of 32 ...
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1answer
55 views

Fix a broken Power Supply using existing connector (Newbie) [closed]

I am hoping to attempt to fix my childrens ride on electric car as the power supply was left charging and has cracked / broken (see pics). I am completely new to electronics, but was hoping to ...
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50 views

Homework: DC Circuit analysis

In the following circuit I need to find current I1 if the given parameters are E1=0V,E2=15V,E3=60V In the second case, given parameters are I2=100mA,I3=40mA,E1=30V,E2=E3=0V In both cases, ...
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2answers
85 views

Potentiometer as Voltage regulator 12V to 6 - 12V range

I am new to electrical engineering and I would like to build simple circuit with potentiometer as voltage regulator. I have simple circuit, as you can see in attached picture below. I have ...
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2answers
122 views

Can I use a transistor to switch to battery backup power when main power goes out?

I am putting together a circuitry, and I want the circuit to continue running even after main power goes out. So I was thinking about this idea of using a PNP transistor and a one-way diode to ...
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2answers
112 views

Make 5v 3A dc power supply

i want to make 5v dc supply so that i can run 3 dc motors in parallel having spec 5v each and max currrent rating 900ma.but i have transformer of 3amp step down transformer 220v to 12v to run lm7805 ...
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1answer
52 views

DC 5V to Audio Line Level

Firstly, I'm a hobbyist and have a lot to learn. I'm trying to get a 0-5V signal created by a microcontroller to +/-2V audio level. I don't want to spend a lot and would like to keep the part count ...
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1answer
65 views

can i increase my adapter current? [closed]

i have an adapter that its output is: DC 4.9 volt and 450 m ampere i want use this adapter for running three 6 volt dc motors but the adapter output current is low, so i want amplify that. can i do ...
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2answers
83 views

Can a voltage source be DC and generate a sawtooth signal?

Pretty much what the title says. I'm fairly confused with this simple question. Shouldn't waveforms which change amplitude be AC? EDIT: So this is about a RAMP Type DVM (Digital Voltmeter). Can the ...
2
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2answers
68 views

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
97 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
65 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
53 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
52 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
21 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
81 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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2answers
131 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. ...
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1answer
44 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
65 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
112 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
124 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
35 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 - ...
4
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2answers
819 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
60 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
72 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
94 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 ...
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2answers
110 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
32 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
39 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 ...