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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5
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2answers
336 views

DC bias difference between square and sine wave?

I have a 90V DC voltage, VPP. I have a 10Vpp (-5V to 5V), 100 kHz square wave that I'd like to re-bias at VPP/2. Here is the output from LTSpice: Biased output starts at 45V and then 10V is added, ...
1
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1answer
44 views

Should the Gauge of wire be consistent for DC

I'm looking at an ATX Power Supply with 2 rails each with a specification of 12 volts @ 20 Amps. That should be a maximum of 240 watts (per rail). The modular plugs/cables that plug into the power ...
1
vote
2answers
61 views

Why do you need a thicker wire when wire length increases?

Question: So far I've found that the thickness of the wire influences the resistance. A thicker wire has less resistance. Also, the length of a wire has a linear correlation with the resistance. 2x ...
0
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2answers
37 views

Automatic DC 3 line switch

please help me with an advice. I need a dc switch, but the switch should work from electricity. For example: 2 in lines and 1 out line. One in line is 9 volts and out line is 9 volts, but the second ...
0
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1answer
35 views

Wireless DC Motor & Linear Actuator Control

These are the 2 items that I have: 24V 110RPM 1Amp DC Motor. 24V 100mm Linear Actuator. First Question: To run the DC Motor I am thinking of getting this 24V 2A power supply in the hope that both ...
0
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1answer
52 views

Arduino SSR 5V DC (Mager GJ-3FA-L)

I just noticed this SSR that was for DCV instead of all the others that are normally for AC. Although I can not find the datasheet for it, it does seem compatible with Arduino. eBay auction site ...
0
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1answer
86 views

L298N damaged? What to do?

I'm trying to control a DC motor with the L298N motor driver and it worked for a brief moment. I've used the setup mentioned in this video tutorial, but someone in the comments said that with this ...
1
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1answer
78 views

Wild AC to DC for Arduino and high power leds

I've seen some similar posts but none did exactly match. I'm looking to power a Arduino Uno and 1x 10W + 4x 3W LEDs (Using BUZ11 from Arduino output) from a very wild AC source which is on a very ...
1
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1answer
64 views

DMM Auto-Polarity / Polarity detection

I have understood how auto-ranging is typically achieved on a digital multimeter, but I'm having trouble finding an example of how (DC) polarity is handled. How does the meter know if a voltage is ...
0
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1answer
25 views

voltage regulator BD9C401EFJ

I am using the BD9C401EFJ for 9V to 5V conversion(with enable pin pulled high). So - I/p = 9V and o/p = 5V. I was just doing some expts and saw that when I give no i/p, and I give 5V at the o/p side ...
1
vote
3answers
70 views

Will running a DC motor below stall current damage it?

We have DC motors that power wheels on a car. Because of internal friction, the motors will not actually rotate until they are given 50%+ power. However, they do make some neat noises within this ...
0
votes
1answer
60 views

Solar panel and little computer fan

OK here is the spec: Solar Panel 4"x6" 200mA 7.2v Fan small : 20x10mm, 12vdc, 60mA, 2.17cfm medium : 40x20mm 12vdc, 140ma, 8.28cfm What I'd like to do, is to be able to run the fan hook to ...
0
votes
1answer
58 views

Board Input DC voltage

I need to receive a 24V signal from an automated industrial system. The receiving board is a UDOO system that its I/Os can handle voltages until 3.3V. Any ideas on how can I make things work?
4
votes
1answer
79 views

Why does capacitor value changes when capacitor is DC biased?

I have seen ceramic capacitor value varying under various DC biased levels. Dc biased was a huge factor as capacitor value is reduced by 50% almost? Why?
0
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2answers
59 views

Basic question regarding power consumption of different devices

I have current values for devices measured at different DC voltages. 4.2mA at 2.4V 68.8uA at 3.0V 44mA at 2.0V 65mA at 3.4V If I were to power them at a voltage of 3.6V and would like to ...
1
vote
1answer
52 views

Differential Drive for Heavy Robot

I'm asking here another question in relation to my previous one. I would like to know how would one proceed when you want to control a heavy robot with differential wheel drive. When it comes to ...
0
votes
1answer
51 views

Will a Transformer work from a DC inverter's output? [closed]

If so, is it ever more efficient to use an inverter into a transformer to dial down DC Voltage?
0
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2answers
80 views

What power strategy should I use for this board? [closed]

(Similar but not quite the same question here. ) I'm repurposing an existing synth board which is powered like so: -15VDC GND +12VDC I'd like to power it ...
2
votes
2answers
94 views

Why are some terminal blocks blue and grey in color

Looking at some terminal blocks like the one below, why are the top level positions color coded blue while the middle ones are in grey? I understand yellow-green are for ground connections. I am ...
0
votes
4answers
90 views

What gauge wire for 36V (DC), 5A peak?

I've searched online and found wire gauge calculators but I still can't seem to find a reliable answer. What gauge wire do I need to carry 36 volts (DC) at 5 amps (peak) for 4 meters? This cable ...
2
votes
2answers
97 views

How to choose what voltage power supply to use?

I'd like to build a keyboard emulator, and I've found three links that detail the process: 1, 2, 3. Here's the rough circuit: The thing is, across the various articles I've read, people are using ...
0
votes
0answers
77 views

Can I use 80 white 5mm LEDs with only one resistor? [duplicate]

Can I use 80 white 5mm LED with only one resistor? I use 12 volts power supply (up to 2 amps). I tried 100 LED design but I used 50 resistors (2 series led + resistance). So was a lot of soldering. ...
0
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0answers
60 views

Relay needed for an input ot 0.15 V

sorry about the question but I'm a beginner here. I have a very low DC voltage of 0.15V and I want to use a relay with in a simple circuit to light a LED. I'm learning in how to build circuits. So ...
0
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1answer
99 views

AC and DC voltage are constant even though the frequency changes

In the circuit below, why does the AC voltage remain constant even though the frequency increases?
-1
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1answer
48 views

Detecting polarity in a DC device [closed]

I have a device which can be charged with 5v DC. I wish to locate an adaptor for it, but not knowing the device's polarity, I'm stuck. Please note: The device requires 5v DC but has no polarity ...
0
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3answers
66 views

Switching between several high power DC devices?

I would like to control several high power DC devices (12V DC LEDs). From a tutorial, I found that I can control these using a 3.3V PWM input and a MOSFET. From what I understand, the MOSFET only ...
4
votes
1answer
88 views

Op-Amp Sample and Hold Circuit Help

So, I'm trying to modify a sample and hold circuit from "The Forrest Mims Engineer's Notebook", that uses a 353 op-amp, so that it runs off of a single supply: I needed to add a 4.5V (1/2 supply ...
0
votes
3answers
68 views

Is rms value of a positive varying DC voltage same with its mean value?

I know that rms of an AC is totally different than its mean. But what if the voltage is not alternating(DC) but varying by time. For example a noise with a huge offset. How is varying DC measured by ...
1
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2answers
75 views

Advantages of Isolated DC-DC Converter over non-isolated?

I am trying to understand in what type of situation I will need an isolated DC-DC converter instead of a non-isolated one. What are the design criteria that can lead one to one way or another? In my ...
3
votes
3answers
179 views

Power 15 meters of LEDS?

I'm trying to make a display out of 2811 LEDs from China (15 meters long x 7 LED strips). Each strip consumes 18W@5V(3.6A) per meter and I plan to use 7 strips, each 15m long. My calculations show ...
0
votes
0answers
17 views

Can dc adapter be used instead of ac for battery charger [duplicate]

I need to replace my ac output adapter radio battery charger and can only find a dc output model with same watts and amps - will this work safely?
0
votes
3answers
89 views

Low Voltage DC controlling 120 AC, with Arduino

I'm looking for a type of device I can hook my arduino (micro-controller) to that will control a set of lights that require 120VAC. Basically I will be making a light organ, where the arduino will be ...
0
votes
2answers
113 views

DC Supply and Battery in parallel

Hey everyone I'm working on a project where I want to be able to power a thin mini-itx motherboard two different ways. Here is what I'm trying to do: 19V battery will be connected to a relay which ...
1
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1answer
60 views

Inrush Current Limiter for microPC

I'm looking at powering an embedded board PC using a 12V PSU and I'm having some trouble due to inrush current. The board draws 5A for about 1ms on startup and unfortunately this trips my PSU's ...
0
votes
1answer
59 views

AC to DC Filter Confirmation

Of the circuit I need to know the name of and what it is; my guess is, is it an AC to DC current converter? Is anyone able to confirm or deny? What does it act as when its all formed together? ...
1
vote
2answers
91 views

0-12V Adjustable Home Made DC Source not working [closed]

I have a home made dc source that is made a few years ago. Solders at the back of the board are very bad so I can not track the connections very good. But it's circuit diagram is very similar to the ...
-2
votes
1answer
53 views

Using one circuit to switch another [closed]

I have 2 circuits. Circuit A is actually my android phone, for which I've written an app to send PWM signal through audio jack, voltage ~250mV. Circuit B is combination of 2 IR led and 2 AA cells. ...
0
votes
2answers
195 views

How to convert 6V AC to 5V DC

I'm looking to convert 6v AC (.5A) to 5v DC for use in charging a phone via USB. idealy a relatively inexpensive pre existing solution would be perfect, but I've been unable to find anything like that ...
-2
votes
1answer
54 views

difference between a DC motor and gear motor [closed]

Isnt DC motor the same as gear motor? Because what is the use of dc motor without gears?
2
votes
1answer
101 views

Thermography difference between AC current wire and DC current wire?

Is there thermographic difference between AC current flowing wire and DC current flowing wire? And thermogramic differences for drift velocities?
-1
votes
1answer
124 views

conduction current vs displacement current across capacitor [duplicate]

Kindly help me understand the difference between conduction current and displacement current. Quick searches explain that displacement current is associated with changing electric field, frankly ...
1
vote
1answer
95 views

Control of electric actuators

I'm new to this forum and I am trying to find a solution to control three small electric linear actuators I have made for my rc controlled model aircraft, they have mini 6 volt geared brushed dc ...
0
votes
1answer
101 views

How can I decrease a DC voltage without a resistor [duplicate]

I would like to light up a 2 W LED with a 3.7 V power source in the most efficient way possible. The Vf of the LED is 2.4 V. Is there any way I can reduce the voltage to 2.4 V from 3.7 V without using ...
3
votes
2answers
114 views

DC Brushless Motor For Electric Rover

I'm an industrial designer, and am working on building a small electronic rover, however I've been doing some research and I feel a little bit lost in terms of what motor is best for me, The device ...
2
votes
2answers
143 views

Step down 20V DC to 9V DC

What would be the best way to convert 20V DC to 9V DC? Can I use a simple potential divider network and regulate the output? If not, then what's the harm in it? I intend to use the output to power my ...
4
votes
2answers
138 views

Result of constant current through DC motor under different loads

I've done some research on brushless DC motor and have a few questions what would happen when a constant current is sent to a DC motor. From my understanding, the current is directly related to the ...
0
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2answers
92 views

Diference Connecting AC/DC

Why is there a difference between how AC is connected and how DC is connected? For DC, the polarity of the connection matters, but for AC it doesn't.
1
vote
1answer
86 views

System required to allow a small DC motor to continue to operate for a short period after power is removed. [closed]

I have a Christmas Decoration in the form of a "Ski lift" or "Sky lift" with two houses or stations - a high one and a low one. Two "cable cars" are tied to the cord and travel between the two houses ...
0
votes
0answers
36 views

PCB design with 230VAC and 5VDC [duplicate]

I've developed a small circuit that aims to dim a lamp. Iit works fine on my breadboard, so now I'm building my own PCB. I never built a PCB with 230VAC on it and controlled by a 5V microcontroller. ...
0
votes
1answer
94 views

Unused slots in the stepper Motor

The motor I am talking about has six wire slots of which two are unused and wires coming from the motor are restricted to four (4 to 4 jumper connecting wires are there to connect the motor ).So why ...