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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95 views

How to determine the maximum power required by given devices?

I need to power 4 devices with these power input specs: ...
3
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5answers
615 views

Can a charged 120v high voltage capacitor really kill you? [duplicate]

recently I have been hacking few psu and have to deal with some high voltage caps. It sort of scared me, but thinking about it, what is the chance of it really killing me. Is it safe to touch one ...
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1answer
52 views

DC-DC SPMS Boost Converter DCM Prevention

Sorry for the long question, it's really opinions I seek which is why I felt I needed to explain the scenario and how much I know/don't know. I would really like some input on my design. I am ...
0
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1answer
52 views

Control DC Motor with Micrcontroller

I would like to use a microcontroller to control when a pump turns on and off. I will use a 12 volt battery to supply both the dc motor for the pump and microcontroller. How can I interface the ...
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2answers
52 views

DC motor - selection

I'm not an electrical engineer . I would like to know whether a normal DC motor will hold the load when the power is turned off?? Or should I need to install a controller to hold the load at that ...
1
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0answers
48 views

Homework: DC circuit help

I need help with the following problem: Find range of resistance R4 and voltage U4 so that the range of current I is $$I \in [-3A,-1A]$$ E=5V, E4=6V, Ig=1A, Ig4=-3A, R1=2ohm, ...
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1answer
25 views

Minimum current draw of AC to DC converter at no load

I wanted to know if there is a minimum current draw on the AC to DC converters from the AC source when it is connected to an input voltage of 120V (60Hz), when no load is connected at the output of ...
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1answer
30 views

dc motor amp draw based on HP and watts

I repair treadmills and occasionally the motor causes the controller to fail. I use a 20v dc source with no load for the test.I have determined thru testing many motors of the same specs that a ...
0
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1answer
22 views

Timed motor switch

I'm very new with electronics and I'm working on a project, I need to make a motor go forward then after a few seconds reverse, then forward then reverse and so on. I found this tutorial (How to ...
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2answers
65 views

Transformer hum - DC offset? Does this cause transformer breakdown?

I have an integrated amplifier that I like, but it hums - it's an Arcam A22 and contains a big toroidal transformer. It sits on the desk right next to my monitor and I can't live with it. I just ...
2
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2answers
86 views

Using a 12v switch in 120v circuit

Can I use a 12vdc switch rated at 16A on a 120vac that only use 0.5A-1A? I have a similar switch, that is 120v rated at 10A, but it's a little too small. doesn't fix.
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0answers
34 views

0 - 90v pulse power supply [closed]

i wanted to make a pulse power supply from a dc source adjustable from close to 0 to 90 volts. Is there any circuit or any advice to make it? I need only 1A Thank you, Nick
5
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5answers
1k views

Could most AC devices run off of DC rather than AC?

To be clear - I have absolutely ZERO intention of ever doing this. But when I learned what a rectifier does (flip the negative portion of the voltage into positive), it occurred to me that it ought ...
1
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1answer
36 views

Do I need any special equipment to make my circuit run off power from a phone/laptop charger?

Is it safe for one to replace a 5v battery source with a phone charger without installing any other components to prevent power surges or injury to any people in contact with the device? Also, is it ...
1
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1answer
87 views

AC Watts to DC Watts Calculation

Okay, so I'm new to the whole electricity field and I'm trying to get a handle on something so I apologize for any ignorance displayed here. I've purchased a new graphics card for my computer and I'm ...
3
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2answers
217 views

How can I model a relay in LTSpice IV?

I would like to use a 12V relay in my LTspice circuit, however there is no relay in the component list. How can I do? Relay model: SRD-12VDC-SL-C
1
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2answers
39 views

Calculate power supply for step down modules

i'd like to build a system in which there will be step down modules that get their power from an ac-dc converter. there are 5 modules connected to the ac-dc converter (each of them steps down to ...
0
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2answers
77 views

Calculating voltage in a simple circuit

If I had a 12V battery and wanted to use an LED that used 2V and 20mA, then I need a resistor that will drop 10V and provide enough resistance to produce a current of 20mA. Therefore I would use R=V/I ...
2
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2answers
52 views

DC Forklift high current power supply

I have an old 36v DC battery hydraulic indoor forklift. The batteries are 23 years old, and no longer hold a charge for more than ten minutes, although they are a good counterweight. I have tried ...
1
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1answer
59 views

Braking of Motors

Is an induction motor delivering or drawing mechanical power in the braking region? . according to the torque slip curve of an Induction motor,torque is positive and the motor continue to rotate in ...
3
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1answer
49 views

DC--> AC Inverter Connected to a single battery in a 6 battery series

I have 6 x 8V batteries connected in series (i.e.48V) and have a 48V smart charger attached which charges them from regular electricity main supply. What happens if I connect, say, a 24V DC to AC ...
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2answers
55 views

Send signal to gpio when 8V power drops

I want to be able to detect when a 8V signal goes low and send a signal to a raspberry pi over GPIO. A java app will be listening on the GPIO pins for any changes. I would check if the voltage drops ...
0
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0answers
60 views

Replacing parallel 12V incandescent bulbs with LED “bulbs”, voltage problems

My van has six "25W" bulbs in parallel on a 12V-nominal circuit. If I unplug all the bulbs, leaving six empty sockets, then I see pretty much the same 12.5V at the sockets as I see at my battery, and ...
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1answer
51 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
58 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
73 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
34 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 ...
1
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2answers
79 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 ...
23
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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
80 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
41 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 ...
1
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4answers
126 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 ...
0
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3answers
148 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
66 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
25 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 ...
1
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1answer
59 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 ...
0
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0answers
43 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 ...
0
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2answers
54 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 ...
0
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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
176 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?
0
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1answer
79 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
57 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 ...
0
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0answers
53 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, ...
0
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2answers
100 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 ...
0
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2answers
143 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
114 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 ...
0
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1answer
57 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
69 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 ...
0
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2answers
90 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
101 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 ...