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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Electrical resistance converted to wire temperature

I'm trying to get a formula that I can reuse to help me determine wire size and properties. The goal is to heat a 430' wire between 40-100F using 12 volts and 10 amps of direct current. Everyone is ...
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1answer
18 views

Cumulatively excited and Differentially excited DC generator

Is a cumulatively excited DC generator long shunt or short shunt motor?
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1answer
34 views

Equivalent sequence/stepper relay to “FINDER - 20.21.9.012.4000”

I am currently looking at this relay: FINDER - 20.21.9.012.4000. Which is step relay, that makes contact AC output active with coil input DC (12V) [which i need]; and disconnects output when coil is ...
6
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4answers
2k views

What are the highest DC and AC voltages or currents that can be considered as safe?

By safe I mean safe for us when we touch a wire that is not insulated. I have heard that human body resistance is normally 50k Ohm when dry and 20K Ohm when wet. Therefore, these voltages or currents ...
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1answer
29 views

Convert a non-isolated converter to an isolated converter

Is there a way to convert a non-isolated converter(such as R-78C5.0-1.0) to an isolated converter.
0
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0answers
54 views

Diy inrunner motor? [closed]

Could an inrunner be made within 2.5"x9" and also have 150 or less kv and still be capable of roughly 800watts on 6s(24volts)....and not burn up? If so I'm into it if any of you have any advice or ...
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1answer
45 views

Making use of bike battery to charge mobiles without any other power resource? [closed]

I need to make my mobile charging in bike, while I go long tours. Actually the bike battery has DC 12-9 volts power and I saw on the phone charger that there is DC 5 volts (or) can I connect the ...
0
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2answers
59 views

How to purchase the right transformer for an electronic device [closed]

I just purchased an IP telephone that comes with no power transformer. I think the manufacturer assumes that buyers will be using power over ethernet. On the back of the phone where the power jack ...
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1answer
30 views

triac DC ground and AC live

In this example of using a 3Q triac, could the AC voltage flow into the DC terminal?
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1answer
57 views

Using an AC plug for DC current

If I have a plug that is rated 10A @ 250V AC, is it safe to assume I can use it at 10A @ 12V DC? Could it be used at higher current or should its maximum be lower for that matter? Thanks!
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0answers
42 views

AC / DC Axial Fan power usage VS. performance

My question is about Axial fans. Specifically, similarly sized, built and performant AC / DC axial fans. Given 2 fans from the same manufacturer which can push very similar amount of air, with ...
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2answers
68 views

How to find current across a resistor using Thevenin Theorem

It's my first question here. How to find the current through 3 ohm resistor using Thevenin theorem?
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2answers
103 views

Why does AC Current exists? [closed]

I need to know why does AC Current exists? And why not only DC current exists? Most devices needs DC current. I know that DC current is much dangerous then AC current. because of it is alternating ...
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10answers
2k views

Avoiding DC voltage drop over long distances

I am trying to power my IP camera over a long distance from the power socket (about 10m). The included power adapter, rated for 5V 2A is about 1.5m long. I cut the cable and extended it using a ...
8
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5answers
2k views

DC adapters: why so few amps?

If I have a device that draws 5 amps at 12 volts, I can use any 12 volt DC adapter that can provide at least 5 amps. Why don't all DC adapters have the capacity to provide loads of amps!? If all DC ...
0
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2answers
54 views

LM2596 minimum input voltage question

I'm trying to feed the LM2596 (DC to DC) booster a 9V battery. Now, I see that it has a minimum voltage required of 3V. My question is this: What happens when my 9V battery drops below 3V? Would ...
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2answers
80 views

Power supply with 10 VDC and 2mA

I have device need 10 V DC and 2 mA, can I use DC battery? For example, two batteries with 5 V DC and 1000 mAh?
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1answer
90 views

24V to 5V DC conversion for Raspberry Pi

I'm trying to power several devices off of a breadboard. For simplicity I want to power these all from the same PSU. The highest voltage amongst the devices is 24V. I was looking to use a 24V 2A ...
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1answer
63 views

How to supply multiple 12V DC 3 amps motors?

I need to supply four DC motors 12V @ 3 amps with a battery pack. I was wondering which characteristics should have an hypothetical battery pack to supply all four motors together. How many volts ...
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0answers
76 views

Insufficient Power when using one power source vs two [duplicate]

So I've been working on a wireless remote relay switch using several components and have struck a break wall. The issue I'm having is that the D0 siginal output triggers the relay but only at short ...
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2answers
96 views

Using a DC voltage as the base for a transistor to amplify AC Voltage

I'm a little new to electronics, particularly transistors, so I don't know a lot of the different types and inner-workings of them. I have a diagram which, hopefully, will gradually increase the ...
2
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1answer
109 views

Electric motor will only start turning at lower voltages

I have a tiny DC motor directly connected to this power supply. The motor starts just fine when the supply is set to 4.5V. I can then change the voltage to 6V and it continues to run just fine. ...
4
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1answer
177 views

Headphone output: DC Bias?

Need some electrical advice, as my days of my Electrical Engineering degree are well behind me... I have 4 PMR446 radios ("walkie-talkies"). They work great, but when using an earpiece, every-time ...
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1answer
63 views

How create a low-voltage boost (~4v to 5v)

I am looking for a circuit that will go from a Li battery that has a voltage between 3.6v and 4.3v up to 5v - and I have seen similar questions such as this and this, but those just recommend ...
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2answers
98 views

Measuring current around 20 amps

I have an electrolyzer that works with car battery (12 volts DC) and draws current around 15 amps. I have a digital multimeter that can measure 10 amps at most. So how can I measure the current? Maybe ...
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2answers
55 views

What is the effect of the rated current for a breaker when a 230V 6A rated circuit breaker is used in a 24 V DC circuit?

I want to use a normal household breaker for connecting to a 24V circuit. The input supply is a 230V AC to 24V DC SMPS. The output of the DC converter is connected to a load (rated 180 milliamps @ 24 ...
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2answers
69 views

Full wave doubler difference and connection of neutral and phase

I'm testing a circuit for creating am unregulated "HV"DC source. The circuit is like this: simulate this circuit – Schematic created using CircuitLab The example I'm using uses a Variac ...
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1answer
126 views

AC voltage gets mixed with DC

I am using ATS (automatic start) for my generator. Its programmable IC goes out of work after 2 or 3 days and I have replaced 3 ATS card. My card supplier says that you are somehow getting AC voltage ...
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2answers
101 views

How to select most efficient motor for generator?

First post. Please forgive me if this is a stupid question. This post can be broken down into two questions. I am building a bicycle generator, but am new to the field of EE. I am trying to select ...
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2answers
179 views

How to amplify DC Voltage to be used like supply to 2km?

I want to turn on a device away from the voltage source to 2 kilometers. My device operates at 24VDC or 48VDC / 35W. I need to know how is it possible to amplify the voltage from 24Vdc to 240Vdc or ...
0
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1answer
71 views

Good volts and amps but phone still charging slowly

I am really new to the EE game and am still tinkering. I have built my own portable DC power source similar to a Minty Boost from scratch and plugged it into the USB port of my Galaxy S3 and it ...
2
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2answers
107 views

Circuit to pass voltages above a threshold level

I have a sine wave signal centered around 2.5 volts (1/2 Vcc) in which I require the the upper half only, brought down to 0 volts, so a 2 volt peak-to-peak input around 2.5V would become a half sine ...
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1answer
35 views

Can the volts and\or amps in a repalcement DC power cord vary without problems? [duplicate]

In general I've always wondered about this but now I have lost the DC power cord to my portable speakers. The manufacture does not have a replacement or at least one I can find. The specs are 12.5 V ...
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1answer
82 views

24v 450w DC motor powered electric bike connected to a lith-ion battery pack (56v 6.5a)

How do I prevent the DC motor from burning out using this battery pack?
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2answers
109 views

What wattage solar panel required for AC 1000 watts

If my house load is 1000 Watts AC/220V, then 1000 Watts DC/12V solar panels is not enough. What wattage solar panel would be required for AC 1000 watts?
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3answers
496 views

How many Watts DC are equivalent to 1,000 Watts AC? [duplicate]

How many Watts DC are equivalent to 1,000 Watts AC? For instance, my load in AC is 1,000 Watts 220V. Then, how much DC watts would an equivalent load dissipate in 12V or 24V DC system?
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2answers
67 views

Control automotive AC switch via TPS voltage

The A/C compressor is engaged via a single wire that comes from the 'A/C' button on the dash board. I want the A/C button to disengage when the throttle is at 50%. The throttle position sensor (TPS) ...
0
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3answers
166 views

Grounding a capacitor?

Noobish question. I'm trying to make a dc variable voltage power supply. I will include the schematic which I am trying to build. In the schematic there are two 1000 uf capacitors which I believe are ...
0
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3answers
112 views

Diode in parallel with two DC sources

Please help me to find the answer for the following question from Flyod 9th Ed. Determine the voltage across the diode in the following figure, using the complete diode model with r'd = 10 Ohms and ...
1
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1answer
80 views

How do I replace an existing servo with a geared DC motor?

I am a complete beginner, just getting into the world of electronics, in particular robotics. I have found a really nice open source set up that I want to build on and change for my own ends. The ...
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4answers
193 views

How to drop 240V DC to 5V DC

I would like to drop a 240V DC voltage to a 5V DC voltage to supply electronic. The 5V stage needs less than 5mA in current. The solutions I looked at are: Resistor divider (Not really ...
0
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0answers
59 views

How can I use a 9v chaser board to run LED strips

a few years ago I bought an LED sequencer circuit board kit. Once assembled you can adjust the pace and the brightness with 2 POTs of up to (I think) 8 LEDs. this board runs off of a 9v battery and ...
0
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1answer
83 views

3V and 5V supply Topology (Embedded Design, Mixed Signal)

I am developing a mixed-signal embedded system that requires both 5V and 3V rails. The 5V rail powers an analogue sensor and a precision ADC. The nature of the sensor is such that its output will be ...
0
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1answer
46 views

Varistor over clamping voltage at DC

First of all, I know I should not use a varistor at a DC level higher than its clamping voltage, but I want to do it for a test (destructive or not). What I want to know is what is the maximum current ...
1
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6answers
215 views

Why do cables and batteries have a positive and a negative side?

I am a beginner in electronics, mostly self-taught. If electrons are negatively charged and are the reason for electric current why is there a 'positive' side on a battery and negative one? Don't ...
2
votes
1answer
91 views

DC current stopper [closed]

I don't really know what I am looking to make is called so I am going to try to explain it. I set up a motion activated light in my room. The lowest time interval is 60 seconds and I am okay with ...
1
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1answer
80 views

DC motor spun clockwise then counter clockwise creates AC current?

I am making a generator with a DC motor but the style of turning the rotor would be clockwise and then counter-clockwise, and I would want to capture as much current as possible so I hope it could be ...
0
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1answer
80 views

Battery pack for DSLR coupler

I am planning to make a battery pack, by using rechargable batteries, that i can use to power my DC-coupler for my DSLR camera. (Ref. Image) On my original camera battery it says 7.4V 1.2A but i ...
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1answer
74 views

VHF radio - Motorola GM340 - could I have damaged it with too much current? Why would it not be damaged by being connected to a 12v battery? [closed]

I connected a Motorola GM340 VHF radio to the 12v DC converter for another radio, an ICOM IC78, which gives 13.7v at 16 amps. The wiring did not have a fuse. As it did not work, I wonder if the ...
0
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0answers
41 views

LED bulb that works on both 64 volt DC and 110 AC

Can anyone advise on a reliable/cost-effective way to modify a screw-in LED light bulb so it will run on an AC power supply that has a battery backup where DC is provided in backup mode (this is for ...