Fundamentals of electricity, electronics, components, or theory

learn more… | top users | synonyms

0
votes
1answer
51 views

Calculating the gauge of wire required for the secondary in a Tesla Coil

I am looking to build a small Tesla Coil at home with limited supplies. I am reasonably confident (well.. as confident as a biologist can be!) with my calculations so far, however I have hit a mental ...
0
votes
0answers
52 views

voltage and current amplifier

voltage amplifier does voltage amplification current amplifier does current amplification Is there something like power amplifier or power amplifier is just same as current amplifier?
3
votes
3answers
74 views

Help Trobleshooting my first solderless circuit on a breadboard

I'm working on my first project from the book "Electronics All in One for dummies", chapter 6, book 1. I work through all the instruction but I cannot make the LED blinks. The circuit diagram is: ...
-1
votes
1answer
144 views

Learning the Basics of Circuit Design [closed]

This question was put on hold, citing the fact that any answer would be based on opinion. I can't really argue that point, but I do believe that in this case the point is irrelevant. I am asking for ...
1
vote
1answer
42 views

What is the equivalent of a beep on a multimeter without a beeping function?

I have a multimeter that does not have a beeping fucntion and I need to test for continuity. Set to 200 Ω, the multimeter shows 1 when the probes aren't touching, ...
3
votes
2answers
135 views

RLC - Understanding Phase Shifts

I'm having trouble understanding intuitively phase shift for RLC circuits. For example, I have seen the following: In the low-frequency regime, which element is the dominating element (highest ...
1
vote
1answer
63 views

Bypassing input capacitor with a microcontroller

I am designing an amplifier stage and I would like to be able to switch between AC or DC input coupling. How do I achieve this with a microcontroller? I was thinking about using a relay, but it ...
4
votes
3answers
245 views

Calculate op-amp output voltage

I am trying to calculate the output voltage of the circuit. I know that this is a voltage follower, but I am trying to understand how it works. simulate this circuit – Schematic created ...
2
votes
2answers
95 views

Why 10Log(p1/p2) and 20Log(v1/v2)? Why not just 10Log(x1/x2)? [duplicate]

Based on my very basic current understanding of decibels in electronics, it is said that I should use the db = 10Log(p1/p2) formula if I want to calculate the power ...
0
votes
1answer
112 views

Insufficient ground supply on my circuit? Ground capacitive foil

I'm playing with a wireless sensor device (with atmega, xbee, and Capacitive sensor (simple foil)) that works fine with the lab power supply but as soon as I try it with AA batteries stops working. ...
4
votes
8answers
783 views

When does the placement of a resistor matter?

I've been a programmer for years but am very new to electronic engineering. So far I see people saying it doesn't matter where a resistor goes in your LED circuit as long as it is present, but it ...
2
votes
2answers
95 views

Only Allow One LED To Light Up

I'm trying to design a simple circuit for a 4 LED indicator. Its basically like a game show device that has four buttons. The first one to press their button would have their LED light up and "lock" ...
0
votes
1answer
103 views

Basic voltage divider issue in my amateur circuit XBee

Once again I need your help in my project. I have a 4,5v powered circuit. I put a voltage divider with 2 resistors in series to reduce my initial voltage of 4.5V to 3.4V (to feed an XBee module). The ...
0
votes
3answers
188 views

Why use a resistor for Pull-Up? [duplicate]

I just got my first Arduino and had a question about pull-up resistors. I was trying to connect a push-button to the Arduino at pin 2, and if it's HIGH then I write HIGH to pin 13. Now, in the ...
0
votes
1answer
121 views

How can I create an SCR using a PNP and NPN?

Several times I have seen an SCR described as similar to a PNP and NPN transistor linked together. But any attempt to replicate the idea seems to fail. In the circuit below, for example, the LED is ...
2
votes
2answers
101 views

What Does Rated Load of a Tactile Switch Mean?

I want to connect a tactile switch to an GPIO pin of MSP430 (which runs on 3.3 volts). The datasheet of the micro-controller says that IO pins can withstand max current of 6mA. The tactile switch I ...
0
votes
1answer
255 views

Arduino + transistor to switch PC fan on/off

I have: an Arduino UNO a 12V PC fan with 1.68W rating (140ma). 2n3904 transistor 12V 500ma power supply to connect to Vin. What I would like to do is to simply use a digital output pin on the ...
0
votes
2answers
118 views

LEDs, Voltage and Resistors

I noticed that a Christmas Light uses 20 LEDs in series parallel, operated by 2 AA batteries (3V) without a resistor. I thought you always need a resistor? Would it be possible to run them on 5V ...
0
votes
1answer
91 views

Photo transistor in parallel

I'm a beginner and trying to figure out how this circuit works (its a simple circuit that glows an LED when dark) : https://www.youtube.com/watch?v=eIGWWKThprI&list=UUhtY6O8Ahw2cz05PS2GhUbg#t=65 ...
0
votes
1answer
58 views

Electronics by Example [closed]

I am interested in learning more about electronics. I know some basics about resistors, capacitors, transistors, and diodes. I would like to learn more about things such as operational amplifiers, ...
-1
votes
2answers
112 views

How do I solder to these pads?

Quick question. I'm trying solder some wires onto the 5 pads (top right of board) in the image. What's the best way to achieve this? I cant get the solder to stick to the board and I have no flux. I ...
8
votes
4answers
1k views

555 timer: how to set values to take an hour

I'm new (and novice) in electronics. I came to seek your knowledge to see if someone can help me with a very basic circuit. It is a 555 chip, which should light a LED (for about 1/2 second) every ...
2
votes
4answers
154 views

How and why is a magnetic field transmitted with alternating current?

I apologize for the basic question (or if it is incorrect in its assumptions,) but how does one account for magnetism in alternating current? If I generate alternating current to a motor, why do my ...
2
votes
1answer
270 views

What does lumped element mean?

Can anyone explain me the meaning of lumped element and lumped circuit abstraction in detail. What does lumping or discretizing matter mean?
5
votes
1answer
284 views

Mounting AC-DC converter on PCB

I need to figure out how to physically mount the following AC-DC converter to a PCB to be used as part of a regulated power supply. The pin height is min 3.0 mm. Should I mount it as a through-hole ...
0
votes
1answer
57 views

Should I assign currents to voltage sources in my circuit analysis

Mortals! I apologize if my question may seem, foolish, but I have a need of understanding a process in analyzing circuits. You see, when we are looking at resistors (non-sense, my lightning never ...
18
votes
9answers
3k views

Why are electrons not pushed out from the conductor at an open circuit under the influence of a power source?

Frequently, electric current is compared with water flow. For example, if I make a hole in a water tank, water will flow till the tank pressure and the atmospheric not become equal or the tank becomes ...
0
votes
6answers
157 views

Closing two circuits from one button press, with a delay?

From one button press, I want to momentarily close two circuits with a small (< 1s) tuneable delay in between. What term should I google for to find a schematic? (For clarity, I want to press the ...
0
votes
3answers
137 views

Working of RC Phase shift Oscillator?

Figure show a RC phase shift oscillator using Op-Amp with gain 5(Vo/Vi). My assumption : Circuit is generating a sine wave with a peak to peak voltage of 10v. Consider positive maximum point (+5V) ...
-1
votes
1answer
77 views

Components Purposes. Just need a verification

I just need to know if there is anything I need to add or remove. And also What is the purpose of a switch transistor(Q1)? I need a simplified explanation. Thanks in advance
-3
votes
2answers
153 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 ...
16
votes
3answers
2k views

What operation could cause the inductor or the capacitor to explode?

In really early days of electronic school, the teacher used to say something about not unplug power too quickly at an inductor or capacitor and we were used to slowly turn the voltage generator from a ...
1
vote
2answers
189 views

What are quartz crystal oscillators?

I'm a beginner in electronics and I found two quartz crystal oscillators, each one has two pins. Their numbers are: sjc4.000a ee4.000 Is it possible to know the ...
0
votes
2answers
174 views

How can two steel balls with same amount of charge be at different voltages?

Maybe this is the most fundamental question, but still it eludes me. Is it possible for two balls each containing 1 Coulomb of charge be at different voltage levels, say 1V and 2V relative to a ...
1
vote
1answer
76 views

Electrical Engineering Math, showing time independence? how?

I have a cheat sheet provided by the teacher about the calculation of the Coherence Time, however I get lost along the way. There are 2 paths of a signal at: Path 1: \$\phi_1(t) = ...
2
votes
3answers
1k views

What is Doppler Spread

What is the plain English explanation of the Doppler Spread? Looking at different sources I come across complicated definitions which I struggle to understand. Example for such one: Doppler ...
2
votes
2answers
126 views

What makes DSSS a more robust transmission technique compared to FHSS?

In many textbooks it is stated that DSSS is more robust than FHSS. Especially in terms of interference and delay spread? What is the exact reason. Lets say we multiply a given bit 1 with a larger bit ...
0
votes
1answer
79 views

Plain English explanation of the Space-time Code Block by Alamouti

I checked about the Space-time code block online, but all of the explanations are either short or too simple, or too mathematical and complex Could anyone here provide an explanation of what ...
0
votes
2answers
51 views

How are the Intersymbol Interference and Symbol Time (duration) related to each other?

In a lecture slide I noticed that OFDM(Orthogonal frequency-division multiplexing) mitigates the problem of Intersymbol Intereference over wireless systems because the symbol time is increased, in ...
0
votes
1answer
74 views

Generating a desired pulse train in Xilinx ISE software

Need some help with VHDL and FPGA since I am new to it. I have a Virtex-4 FPGA and I wish to generate a binary pulse train of 16 pulses from FPGA using VHDL programming. My desired pulse train will ...
2
votes
2answers
122 views

What phenomena does “Coherence Bandwidth”?

Could anyone please provide a simple explanation of what Coherence Bandwidth means, and how is that related to Delay Spread. I read some articles but they don't help me to form the relation between ...
1
vote
2answers
131 views

Explain Rayleigh Fading in plain English

For a couple of days I am trying to understand the Rayleigh Fading model, but I am failing to. I look at various articles and tutorials online, everything goes fine up to a points, but then a lot of ...
1
vote
2answers
2k views

Connecting a potentiometer

I know how to connect potentiometer, but to be honest I don't know why. I would really like to understand what I'm doing. From what I have read the input voltage and the ground should be connected ...
0
votes
0answers
62 views

Inducing Eddy current in wet clothes

Is it possible to induce eddy current in wet clothes and dry them using the resistance heat generated? I don't want to connect any wires to the clothes.
1
vote
1answer
293 views

Why would we need to ground an AC source?

I'm new to this field hence this weird question. Why would we need to ground an AC source? Why wouldn't it be enough to have just one pole to get an AC current going? I understand why it wouldn't work ...
0
votes
2answers
168 views

How to understand the “basics” of electricity? [closed]

I want to be a self-taught computer engineer ... massive goal, but it's what I want eventually. I check out textbooks and online resources, but I feel like I need a prerequisite somewhat -- I still ...
1
vote
3answers
212 views

Powering multiple relays

I'm trying to control five * 5v relays from a micro-controller. However I'm having issues powering more than two at a time Some notes The power source is a 800ma 10V ac adapter. 7805cv voltage ...
3
votes
1answer
57 views

Capacitor charging: do electrons migrate from the source to the dielectric?

Encyclopedia of Electronic Components - Vol1, pg:98 by Charles Platt Electrons from the power source will migrate on­ to the plate attached to the negative side of the source, and will tend to ...
2
votes
2answers
268 views

Why there isn't current in R3?

simulate this circuit – Schematic created using CircuitLab Why there isn't current in R3? Does it depends on the resistance of R3?
1
vote
1answer
110 views

How R equivalent can be found?

simulate this circuit – Schematic created using CircuitLab How R equivalent can be found (without using star delta connection)? the answer said 3/5R