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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61 views

Ways to step down a dc voltage

I was in an interview explaining step down (buck) converter and was going well. But then he asked me which other way can you think of that could step down a DC voltage? I said transformer but ...
2
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0answers
39 views

High voltage DC offset servo

I'm working on a project and I need some assistance. I have an audio tube amplifier output stage that I need to have adjustable operating points while maintaining a DC null at the output. As you ...
0
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1answer
43 views

Noise in DC causing unwanted LC resonance

I have a circuit like this: The part on the left generates AC signal. The part on the right detects whether AC is running through the branch when S1 is closed. I use a resonating LC circuit which ...
0
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2answers
44 views

Calculating voltage in a two-loop circuit

I have come across the following question: Clearly I3 = I2 + I1, however I am unsure over the voltage of R3. Following from the fact that voltage drops in a closed loop sum to 0, the p.d. across R3 ...
3
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1answer
101 views

Why is AC earth connected to DC ground in laptop adapters?

If I were to plug this type of adapter into an ungrounded socket then voltage will leak to the DC ground through the AC filter capacitors. So why is the DC side not left floating? What are the ...
0
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1answer
36 views

Irms to Idc for inductor selection

I'm trying to build a buck converter using one of Power Integrated switches and their online design software lists the inductor rating in Irms. However, most inductors have their current ratings in ...
0
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2answers
65 views

Multiple resistors to reach needed value?

Im converting an old floodlight to a cree led to run off my solar setup for a yard light I need a 27ohm resistor for a 3.5v 350ma single led to run off 12.5v, but don't have any that value, what ...
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0answers
42 views

How do I calculate the size of the snubber capacitor needed across a DC commutator to clamp the transients? [closed]

I have an old DC power supply of 40 volt and 40 amp capacity. I wish to send this energy into a mosfet switch, so need to clean up the transients generated by the brushes as they slide across the ...
1
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3answers
183 views

Why alternators are used to generate DC?

Why is it that to generate DC, it's often an alternator that's used? Couldn't commutator rings be added and do without AC-DC conversion? I'm asking because I wonder how efficient it usually is for a ...
0
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2answers
42 views

DC High Voltage Line Splitting Problem (Electrode “Tuning” Application)

I am having trouble coming up with a solution to a problem engineering a DC circuit that can take a single line input (Vin) and split into two outputs (Vout1 & Vout2). The goal of the circuit is ...
0
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3answers
61 views

AC-DC Conversion; How Much Can I Draw?

My question is how much Amperage can I draw in DC using this kind of setup. I have a 3055 and it's rated at 15A. Is that my max draw then? Power systems aren't my thing, so I'm out of my element ...
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0answers
38 views

Can DC current be lethal? [duplicate]

can someone get a shock while comes in contact with dc current? if yes then what would be the amount of this DC current to kill someone? how much ac current is needed to kill a human?
1
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3answers
84 views

Regulate 9VDC@7A PSU output down to 3 to 7.5 vdc at a 1Hz sine wave rate

First post here. What would be a simple way to take the output of a switching 9vdc 7Amp PSU and produce a slow 1Hz sine type wave DC voltage that varies between 3vdc minimum and 7.5vdc maximum? Is ...
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votes
1answer
72 views

I need 120 volts DC (yes, direct current) at 20 amperes [closed]

I need direct current at mains voltage--120 volts DC up to 20 amperes. I'm already aware of the plethora of full-wave bridge rectifiers that are capable of rectifying 20 amperes of mains power, but I ...
0
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0answers
41 views

Why does multimeter show a voltage of 10 volts in AC mode when I try to measure the output voltage of 5 volt supply? [duplicate]

I was carrying out a small experiment on the working of regulated power supply that consisted of a Transformer, a bridge rectifier followed by filters. I applied 230 volts from the AC mains. Using my ...
1
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2answers
82 views

Currents when converting voltages down

Okay, so I have what could be considered a silly question I should've probably learned when I started working electronics way back when, but I just now thought of it and haven't really needed to ask ...
0
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2answers
49 views

Calculated resistance of an LED

I am working on some circuit lab homework this week and am a bit stumped by something I just can't seem to find anywhere in my Circuit Analysis I book. The lab has me construct the following circuit ...
1
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3answers
70 views

How to use the power good signal properly?

I'm powering a circuit from a buck converter. I've seen that many buck/boost converters (for example, TPS62177) have a PG or power good output signal which ...
11
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3answers
322 views

Help me solve this DC circuit problem

The circuit looks like this: All the elements are known, except for \$I_{g2}\$. \$E_1=3V,E_4=10V,E_6=2V,E_8=1V,E_9=4V,I_{g7}=1mA,\$ ...
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1answer
46 views

In DC motor'name plate there is written only 12 or 24 volt there is no any description about current and power why?

In DC motor'name plate there is written only 12 or 24 volt there is no any description about current and power why?and in ac motore there is written all details about voltage and current and power.
0
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1answer
67 views

Share battery pack with Arduino and DC motors

I used 6 rechargeable AA batteries (total 7.2V) to power my Arduino (UNO R3) Car's two DC Motors (using L293D IC as motor driver). I used separate 9V battery to power Arduino itself. But I want to ...
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0answers
32 views

How does a virtual DC bus provide negative dc voltage in transformer less inverters?

How does the topology (1st pic) eliminate Common mode current found in PV panels connected to grid without isolation transformers?
5
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2answers
810 views

Can I use a 5V phone charger to run a device which expects 3.7V battery power?

I have an old mp3 player which originally ran from a 3.7V LiPo battery. It could be charged from USB using a mini-usb connector. The device goes into charging mode when power is present at the usb ...
0
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1answer
46 views

Soldering ACN/ACL (blue/brown) wires to outlet plug?

I have a 12v 5.0a AC to DC power converter. I want to solder the ACN(blue) and ACL(brown) wires to an outlet plug I cut that has copper wire (black and white). I hope I am on the right path here. ...
0
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3answers
64 views

Little confusion about dc motors

So for whatever reason I'm having a little bit of a problem understanding why every dc motor explanation says the current switches after every segment in the armature. I mean the current is going to ...
0
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0answers
6 views

Charging circuit [migrated]

I have a motorhome and tow my car behind. Since I have to leave car in accessory so steering wheel is unlocked, the battery doesnt last a long time.. I want to run a dc line from motorhome hookup ...
1
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1answer
58 views

Anolog signal amplification with single supply

I have to amplify an analog signal 0 - 0.3v from a sensor to 0 - 2.5v which the XBee's analog input accepts and onlt have access to one 3.3v and gnd power supply rail(no negative rail). I've tried the ...
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3answers
73 views

Which motor would work best as a generator? [closed]

i've been doing a lot of research into motors to use as a generator in a medium sized wind turbine project. I am lost as to what to do, will a large AC motor with a bridge rectifier be a good ...
0
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2answers
24 views

Help connecting solar cells to be 12 V

I just purchased a lot of 40 solar cells each with 1.8 W, 0.5 V, and 3.6 A. This gives a total of 72 W. Ideally, I would like to connect the cells in a manner to yield 12 V. I know I can connect two ...
0
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0answers
6 views

arduino and gsm module receive [migrated]

Can you help me with the codes? I have gizduino(arduino clone), i used the codes in receiving sms from the internet but what i receive is a symbol "y" with two dots at the top. Whats wrong? My gsm is ...
0
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1answer
47 views

Voltage between AC phase and DC link

Let there be 3-phase rectifier connected to the standard electricity grid with 400V between phases. Measuring voltage between one of the phases (AC) and negative terminal of the rectifier output (DC), ...
2
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1answer
72 views

Will this computer case fan power a lightbulb?

I'm attempting to help my daughter build a wind generation model for her science fair. I've found some prebuilt kits but the shipping is more than the product. Doing some research it seems she can ...
0
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3answers
82 views

Charging AA Battery with DC Generator

I am trying to recharge AA Battery (rechargeable, 1.2v, 1000mah) with DC Generator which outputs around 3v to 5v. The input for DC Generator is from another 1.5v rechargeable battery with a step up ...
0
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2answers
35 views

Neon lamps in parallel DC

I am making a nixie clock and wanting to use 2 neon lamps in parallel for each colon. However in my test circuit I can only get one to strike at a time. The supply voltage is 170Vdc in order to ...
0
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3answers
41 views

Sample And Hold Adder

I've been playing around with a sample and hold adder circuit. Essentially, I am trying to sample a sine wave with a sample and hold circuit. I want to take that sample and add it back to the sine ...
0
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5answers
126 views

Driving a DC Motor without diodes

As you know, H-bridge circuits are used in order to control DC motors. Switches S1-S4 are closed to turn the motor in one direction, S2-S3 are closed for another. But at the time of changing motor ...
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2answers
99 views

What happens when AC voltage is supplied to DC equipment and vice versa?

I would like to know what would happen if a 240V AC supply is fed to a DC equipment panel or an electronic DC circuit and if a 250V DC supply was fed to an AC motor?
0
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1answer
35 views

powering up the arduino and gsm shield module

i am just wondering if what i am thinking is safe for my modules. I want to power up my arduino x which rated at 5vdc/1A and my gsm module rated 5-9vdc/1.5A, using my bandspeed adapter that has an ...
0
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0answers
31 views

Max operating temperature for a DC-DC constant current boost converter?

I am using a GERI® Dc-dc 250w Constant Current Boost Step-up Module to convert 12V to 30-35V. It is mounted to a 100w tdp heat sink. Two questions. I know the maximum operating temperature for ...
0
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1answer
44 views

Capacitive Moisture Sensor - Is AC or DC better/more accurate?

I am looking into making a capacitive moisture sensor. This has been discussed many times already, but I am not sure what is the better option, AC or DC. I want to run this off of a battery, so DC ...
0
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2answers
76 views

Calculation of \$V_o/V_i\$

I know this might be a bit too specific of a question, but I have trouble calculating \$V_o/V_i\$ in the given scheme. I was given a BJT-transistor and had to find an equivalent AC-scheme (i.e. ...
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0answers
36 views

how to control a 12v dc wiper motor with raspberry pi?

I am going to use raspberry Pi for the first time and am looking forward to any suggestions which describes whether a raspberry pi can be used for controlling a 12v Dc wiper motor or not. If yes, how? ...
0
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1answer
48 views

Calculating current in a dc circuit

How can we get the current \$I\$ if all resistances and current \$I_g\$ are known? Is there a special name for circuits like this one? Is this some kind of a bridge? Edit: Edit2:
3
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2answers
185 views

My (single ended, class A) tube amp sounds great while it's shutting off. What's happening?

So, I have guitar direct in to a single-ended class A (12AX7 and 6V6) Champ-style amp. The amp is from the 60s and unbranded, it's likely a Pepco (Pine Electronics) Silvertone style circuit. It's been ...
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0answers
57 views

Raspberry pi B+ internal power supply ckt?

I have just started to study about raspberry pi B+ (data sheet) Can somebody explain the working of power supply circuit (individual component wise) starting from pg 14. How and why it is ...
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2answers
71 views

High Current DC Power Supply

I'm attempting to build a compact way to charge six laptops (of the same model) so that I may avoid using six individual power cables. I'm trying to make it cost-effective yet safe. My initial design ...
0
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1answer
48 views

DC power connections [closed]

I am building a fixture out of LEDs (COBs to be exact) and I'd like to use a 4 prong twistlock AC power plug for a DC connection. I know this is not recommended but hear me out. My drivers for ...
1
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4answers
113 views

Charging a battery from both solar panel and wind generator

I am a complete newbie to electronics. I have taken up a project that basically aims to generate power using solar and wind energy due to personal interest and have done research but I seem to have ...
0
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3answers
125 views

Where does current go in these circuits?

In both these schematics, the 9V source drives current through the circuit, but there doesn't seem to be any way in which the current can 'return' to the source to complete the circuit. In what ways ...
2
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3answers
103 views

Why is it safer to place a switch on the positive side of a voltage source?

According to the research I've done, it is safer to place a switch on the positive side of a voltage source: http://www.allaboutcircuits.com/textbook/direct-current/chpt-3/safe-practices/ This ...