Greatest Hits
13
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5
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146k
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How do the open loop voltage gain and closed loop voltage gain differ?
The closed-loop gain of op-amp is calculated by the ratio of Vout/Vin. What about the open-loop gain? How does the value of open-loop gain and closed-loop gain affect the performance of op-amp ? What ...
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34
votes
6
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144k
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In an NMOS, does current flow from source to drain or vice-versa?
In an NMOS, does current flow from source to drain or vice-versa?
This Wikipedia page is confusing me: http://en.wikipedia.org/wiki/MOSFET
The above image confuses me. For the N-channel, it shows ...
- 495
6
votes
5
answers
71k
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ICEO, ICBO physical interpretation in BJT
I am stuck with the equation:
ICEO = (1+β) ICBO
My questions are:
What is the physical interpretation of this equation?
Will both the currents exist simultaneously?
Are any of the reverse currents ...
- 93
43
votes
6
answers
183k
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How to connect multiple i2c-interface devices into a single pin A4 (SDA) and A5 (SCL) on Arduino?
I want to add a real time clock module into my little project. I want to display both time and date on my existing i2c 2x16 LCD module.
Both i2c-interface real time clock module and 2x16 LCD module ...
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27
votes
3
answers
154k
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Difference between blocking and nonblocking assignment Verilog
I was reading this page http://www.asic-world.com/verilog/verilog_one_day3.html when I came across the following:
We normally have to reset flip-flops, thus every time the clock makes the ...
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56
votes
6
answers
139k
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Do I really need resistors when controlling LEDs with Arduino?
I'm just trying out Arduino Uno for the first time with 2 blinking LEDs on a breadboard. All the tutorials on the Internet seem to use a resistor. I do know the function of resistors, but does it ...
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68
votes
5
answers
109k
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How to choose value of resistor in voltage divider?
I understand that the output voltage is determined by the ratio between the two resistor values, and that if the both resistors are same then output voltage will be exactly same for all; but what's ...
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1
vote
2
answers
96k
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How to build a 4 to 16 decoder using ONLY TWO 2 to 4 decoders?
Help please, I am new to circuits and decoders and I need some serious help.
How to build a 4x16 decoder using ONLY two 2x4 decoders?
Following the steps we took in the lecture, we are supposed to ...
- 19
2
votes
4
answers
85k
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Relationship of Induction Motor Frequencies
I would like to know how the mechanical rotor frequency [Hz] can be obtained from the electrical stator frequency [Hz]? This is no homework! I have consulted several books as well as the web but could ...
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57
votes
6
answers
186k
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Maximum I2C Bus Length?
What is the maximum length of cable that could be used to connect two I2C devices (I2C master-> I2C slave)?
Yes, I know that I2C is really designed for intra-board communication. I have been tasked ...
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45
votes
5
answers
176k
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How can I use a 12 V input on a digital Arduino pin?
I am creating a controller for a 12 V system using an Arduino Uno microcrontroller. For the outputs I am using a relay shield to switch the 12 V components. I have a 12 V toggle switch that turns on ...
- 623
21
votes
4
answers
205k
views
How to tell polarity expected of a DC barrel jack?
I'm sure this information is somewhere around the internet, but I can't find it.
I have a device that takes a DC barrel jack. I don't know the polarity it expects though. There is a marking though. ...
- 3,376
1
vote
6
answers
139k
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Generator speed, and power output. Frequency
When you have a sudden change in load, I understand that you can expect to see sudden, voltage/current spikes. I also understand that you can expect to see a generator speed up or slow down for a ...
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13
votes
10
answers
8k
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Does a resistor in a simple LED circuit actually make it more efficient or does the resistor just burn off the energy?
Here's what the person was saying:
The combo led+resistor will use LESS energy compared to a led only, for the same applied voltage. (Because energy is proportional to power which is current times ...
- 143
7
votes
3
answers
122k
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Convert Watt to Ampere-hour for battery
I'm trying to find replacement batteries for my UPS, I checked my local store and they dont' have this particular model I need so I'm looking for other brand that does exactly the same.
What I ...
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35
votes
8
answers
123k
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Why is it dangerous use a coiled extension cord?
What aspect of using a coiled extension cord makes it more dangerous than using an unrolled power cord?
Many fire safety websites say that an extension cord should not be used while coiled.
Is this ...
- 2,445
53
votes
6
answers
130k
views
Easy way to figure out a LED's Vf in order to pick an appropriate resistor
I was wondering what the easiest way to figure out a LED's forward voltage is, using measurement tools. I know we can assume red LEDs to be around 1.8V - 2.2V, and that we have similar information ...
- 687
41
votes
3
answers
48k
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Why does this LED bulb have an energy efficiency rating of 'F'?
In my home, I have some halogen spot lights, which have an energy efficiency rating of 'C':
I would like to replace them with more efficient LED bulbs, but looking on the Philips website, they claim ...
- 27.4k
21
votes
3
answers
117k
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What value does ammeter or voltmeter measures (RMS, Average or Peak )?
What value does these meters measure?
Is it RMS, Average or Peak value ?
- 1,235
33
votes
7
answers
22k
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How to ramp up a factory consuming a lot of energy?
Can you please explain how to manage the process of ramping up a factory with a big electric consumption?
I am wondering how it is possible to balance the grid during the start up phase of a big power ...
- 433
65
votes
9
answers
126k
views
How do I saturate an NPN transistor?
I understand that in "saturation mode", a BJT functions as a simple switch. I've used this before driving LEDs, but I'm not sure I understand clearly how I got the transistor into that state.
Does a ...
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38
votes
5
answers
180k
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Can I use the analog pins on the Arduino for my project as digital?
I am new to using Arduino, and I have an Arduino Uno. For the projects I've done, I've only used the digital pins.
I am building a small vehicle that uses stepper motors. I have run out of pins to ...
- 1,093
111
votes
9
answers
117k
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Why does a resistor need to be on the anode of an LED?
Please be kind, I am an electronics nub. This is in reference to getting an LED to emit photons.
From what I read (Getting Started in Electronics - Forrest Mims III and Make: Electronics) electrons ...
- 1,213
32
votes
5
answers
152k
views
What is the significance of -3 dB?
My oscilloscope has 100 MHz -3dB bandwidth. -3dB is 0.707 units (\$\sqrt{2} / 2\$). What does this mean, why 70.7% attenuation? Is there any particular reason for this attenuation level?
- 31.8k
16
votes
7
answers
121k
views
How a person standing on a floor tile and holding a live equipment can complete the circuit?
Can someone please explain the how grounding / earthing to prevent a person from getting electrical shock using simple illustration of a faulty electric iron connected to the 240VAC mains?
I don't ...
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26
votes
3
answers
199k
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Powering Arduino Nano 12volts
I know that the Arduino Nano can handle 12 volts, and it says it is recommended to power it between 7 and 12 volts. So I am wondering do I just hack together a 12 volt adapter to a Mini-B or is it ...
- 403
16
votes
5
answers
95k
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Why do farads multiplied by ohms produce a result that has a unit of seconds?
Why is the time constant (RC) measured in seconds even though the units are farads x ohms?
This is to fulfill my own curiosity as I haven't had much luck at finding the answer. I would be most ...
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49
votes
6
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205k
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MOSFET as a Switch - When is it in Saturation?
I have the following circuit hooked up on a breadboard.
I vary the gate voltage using a potentiometer. Here is what confuses me: according to wikipedia, the MOSFET is in saturation when V(GS) > V(TH) ...
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32
votes
7
answers
122k
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Possible to cut heat shrink tubing lengthwise and reattach?
I need to get some heat shrink tubing around something that is too big on the ends for it to slide over. Is it possible to cut the heat shrink along it's length and somehow reattach it before ...
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25
votes
3
answers
142k
views
How to improve torque and RPM of a DC motor?
I have an FA-130 motor (DC) with permanent magnet, my power source is a 2 AA batteries (rechargeable) so a total of 2.4v.
Assume that all cases will start from the same specification, theoretically, ...
- 353
3
votes
4
answers
85k
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Induction motor electrical and mechanical angle
How do we reach the relation between mechanical angle(\$\theta m\$) and electrical angle(\$\theta e\$) as: \$\theta e = (P/2)\theta m\$ ?
; where P is the number of poles.
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8
votes
2
answers
121k
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Converting Power/Watts in DC to Power/Watts in AC?
How can we convert Watts in DC to Watts in AC? for e.g A device needs 1A and 12V DC input i.e (1A x 12V = 12 Watts) 12 Watts DC. If we use an AC to DC adapter/converter to generate 1A,12V (12Watts) DC ...
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90
votes
5
answers
106k
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Relay vs. Transistor?
Rather basic, I'm afraid, but when would you use a relay, and when would you use a transistor? In a relay the contacts wear out, so why are relays used at all?
- 1,003
1
vote
2
answers
43k
views
How to solve excessive CPU load Proteus error?
I'm simulating a virtual Arduino on Proteus. When I test my code, This error appear:
Simulation is not running in real time due to excessive CPU load
For me, It does not matter to watch the real ...
- 3,812
12
votes
5
answers
71k
views
Guessing power line voltage from the number of disc insulator
Is there a good way to guess the power line voltage based on the number of insulator discs that attach the line to the transmission tower?
Wikipedia seems to suggest that there is a "Typical number ...
8
votes
3
answers
66k
views
Why are h-parameters used?
What is the reason for using h-parameters when describing transistors? Why are they used instead of the physical description?
- 1,173
7
votes
2
answers
75k
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Making a logic circuit with only NAND GATES?
I am trying to create a logic circuit using only NAND Gates for this expression:
(NOT Q AND P) OR R
This question has really gotten me stuck! Can somebody please help?
- 91
0
votes
1
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65k
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Calculating Resistance of Unknown resistor, total current and voltage across each resistor
simulate this circuit – Schematic created using CircuitLab
The circuit above has total power dissipation of 60 watts. I need to calculate:
- Resistance of R2
Since it is given that total ...
- 429
12
votes
5
answers
92k
views
Arduino vs Microprocessor vs Microcontroller
What is the difference between an Arduino, a microprocessor, and a microcontroller? I'm trying to determine what is best to operate a cheap resistive touch screen.
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8
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8
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Power's relationship to Resistance
$$ \frac{V^2}{R} = P = I^2 \cdot R $$
According to this equation, Power is inversely proportional to resistance on the left side and directly proportional to resistance on the right side.
How can ...
- 153
30
votes
6
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131k
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Does LED brightness change with voltage?
When I was young and learning about electricity, a fabulous tool for understanding voltage/current/resistance was an incandescent lightbulb (in my case it was a small 3V bulb). When you doubled the ...
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41
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7
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164k
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How is an XOR with more than 2 inputs supposed to work?
I've just started studying computer engineering, and I'm having some doubts regarding the behavior of the XOR gate.
I've been projecting circuits with Logisim, whose XORs behave differently from what ...
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4
votes
1
answer
72k
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Why choose delta over star connection for a 3 phase motor with a VFD?
With respect to a particular application, why is it better to use a delta connection over a star? I have a motor/pump hooked up to a vfd in delta. For my application, Im required to adjust the flow ...
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23
votes
4
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87k
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Differences between thermistors and thermocouples
As I understand it, both thermistors and thermocouples are temperature sensors. So what are the advantages/disadvantages of using one over the other to measure the temperature?
What are the specific ...
- 10.7k
37
votes
5
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111k
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What's the difference between a potentiometer and a rheostat?
I've seen that a number of schematics will connect the center (common) pin of a potentiometer to one or the other leg, and it then functions more like a rheostat. Is that how a rheostat is wired ...
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12
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8
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95k
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Y or Delta connections advantages / disadvantages
I have been studying three-phase systems for the whole course of a subject (on the first year of the university degree). I have finished now, and I know both "Y" (star) or "Delta" (triangle) ...
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16
votes
1
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105k
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Wiring diagram for USB-C to USB-A cable?
I make USB cables (USB-A to Mini or Micro primarily), but don't have any experience with USB-C. I would like to create a cable that has a USB-A (2.0) connector on one end, and a USB-C connector on the ...
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32
votes
6
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126k
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"Ground" vs. "Earth" vs. common vs. negative terminal
This may just be me not having a degree in electrical engineering or electronics, but the whole notion of "ground" and "earth", when used in electrical circuit diagrams (especially integrated circuits)...
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1
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1
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89k
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How do I find C & L from XC and XL?
Calculating Capacitance and Inductance from Capacitive Reactance and Inductive Reactance
I'm trying to find the inductor (L) and capacitor (C) values using the inductive reactance (XL) and capacitive ...
user126396
24
votes
4
answers
137k
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How to calculate the power dissipation in a transistor?
Consider this simple sketch of a circuit, a current source:
I'm not sure how to calculate the power dissipation across the transistor.
I'm taking a class in electronics and have the following ...
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