Fundamentals of electricity, electronics, components, or theory

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0
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2answers
49 views

Can a COTS FM Radio transmit?

This is probably a really silly question, but I still want to know... Given a standard off-the-shelf FM radio alarm clock, what is to stop it from transmitting radio waves when physical motion causes ...
0
votes
2answers
31 views

Kirchhoff law in Electronics Workbench

I have a task to check Kirchhoff laws in this circuit. If I understand everything right, I3 + I2 should be equal to I1, but it isn't. What's wrong?
0
votes
1answer
47 views

Is there a limit at the voltage you can apply to a transformer primary?

I have a 9v transformer but all it says is that, there is not info on the primary. The voltage supplied to my house is 120v. So, the transformer will just lower the voltage by a 0.075 factor, ...
12
votes
6answers
1k views

Why are crystal oscillators used in clocks instead of RLC circuits?

The timing of quartz clocks is regulated by a crystal oscillator. This crystal oscillator effectively forms an RLC circuit. If this is so, what properties does a crystal oscillator have that makes ...
-1
votes
5answers
121 views

Why does a resistor reduce voltage if V=IR? [duplicate]

I'm sure this is a very simple question, but I have been confused about this topic for a while now. According to Ohm's law, resistance varies directly with voltage. This means that if resistance ...
0
votes
1answer
33 views

How a solar charge controller can work on both 12 volt and 24 volt

Please excuse me for my silly question, I have basic understanding of electrical circuits. I came across a solar charge controller which was rated for both 12 v and 24 v. My understanding is that ...
1
vote
1answer
49 views

Power rating for opto-triac trigger circuit resistors

RHS will be using 220v 400watt bulb 2 simple questions 1- does the 360ohm resistors has to be of high watt too ? 2- all i can find is 5-10watt resistors, can i use them ? would they snub correctly ...
-1
votes
1answer
111 views

Pull Up/Pull Down Resistor Confusion

I have googled the crap out of this but I can never find a good answer. In a circuit with a pull up resistor, why is the input pin fed current with a resistor? A pull down resistor circuit doesn't do ...
0
votes
2answers
55 views

Is a Van de Graaff generator a voltage or current source?

I'm currently studying basics of electrostatics and this question comes to me as any generator must be from either of the two types but which is the fact I'm not able to justify which. From its ...
2
votes
1answer
64 views

What are limitations of Kirchhoff laws in presence of A..C current.what are the bounds on its application in such case?

I'm not able to understand while Kirchhoff's laws seem to be based on very fundamental logic they are still not applicable in some cases. I tried to look for answer in text book but got no clear view. ...
5
votes
4answers
364 views

Understanding current, voltage and resistance

I'm still trying to wrap my head around current, voltage and resistance, and slowly I have the feeling that I start to get some things. Hence, I would like to describe my understanding so far and ask ...
-2
votes
3answers
88 views

Should HDL languages be taught before software languages? [closed]

I'm a Computer Engineering student and learned the basic sequential programming languages (C/assembly/Java) way before I was even introduced to HDLs. Thus, my whole programming logic was based upon ...
2
votes
3answers
172 views

Why does isolation transformer protect from shock?

Perhaps I can best explain the question with two examples: (1) there is PC powered directly from 230V mains (unprotected by RCD or similar), and there is fault in PC that causes line voltage to ...
3
votes
2answers
237 views

Is capacitor reactance [sometimes] defined with negative sign?

Wikipedia currently claims so but I've looked in 6 books via Google Books and it's not defined like that, i.e. it's just $$ X_c = \frac{1}{\omega C} = \frac{1}{2\pi f C} $$ Is Wikipedia full of ...
0
votes
1answer
44 views

Having trouble with light activated circuit.

R1 = 10K 1/4W Resistor R2 = Photoresistor (any type) R3 = 2M2 1/4W Resistor R4 = 1M 1/4W Resistor C1= 10µF 25V Electrolytic Capacitor C2 = 100nF 63V Polyester Capacitor D1 = 1N4148 75V 150mA ...
-1
votes
2answers
71 views

Voltage reduced when using NPN transistor

I'm currently trying to reverse the voltage at a DC motor ports, from 5V to -5V, to invert its rotation. I also want to be able to have 0V at theses ports. I have a micro-controller that is able to ...
0
votes
2answers
70 views

Why do LEDs need resistors and lamps do not in a series circuit [closed]

Obviously a basic question but unbelievably difficult to get an answer I understand that LEDs are diodes and that if you don't limit the voltage to a LED it will blow because it draws as much current ...
2
votes
1answer
23 views

How to determine total circuit voltage and individual component resistance for a series circuit

This is a question from someone who has just started to learn electronics. I'm a bit confused Lets say I have a series circuit with three lamps. Lamp 1 needs 1V, lamp 2 needs 2V and lamp3 needs 3V. I ...
0
votes
2answers
56 views

What is an n-by-n matrix in a series-parallel circuit?

I started reading a textbook about basic electronics and I reached a section about series-parallel circuits. Here is an example of a series-parallel circuit: simulate this circuit – ...
0
votes
4answers
71 views

How do logic gates operate? [closed]

I know what the major logic gates are, I know that each gives a different output depending on the input. However, that's all I've been able to find. Every time I look it up, its a list of gates and ...
0
votes
1answer
49 views

Explain trim pot for VU meter

I have the following schematic that is supposed to rectify the signal going to a VU meter and also trim it, so the user can adjust the position of "0dB". What I don't understand is why and how the ...
0
votes
3answers
83 views

How to improve this amplifier so I can get up to 5 Watt output in 8ohm load

This is Class A amplifier I trying to make up to 5 Watt output for 8 \$ \Omega \$ load. Is this amplifier circuit OK?t gives about 800 mW out on 8 \$ \Omega \$ load.
0
votes
0answers
45 views

What is the correct order and setup of AC coupling capacitor and line driver? [duplicate]

When I use an AC coupling cap along with a balance line driver, what is the correct setup? What happens when I omit the resistor in the following schematics? Is it neccessary? simulate this ...
-2
votes
1answer
83 views

very basic basics [closed]

I just started studying but I've been having problems because my professor assumes that we know very basic things that we actually don't. So my questions are: What do I need exactly to have an ...
3
votes
5answers
785 views

High Current or High Voltage that damages components?

Very basic question here and I'm only looking for a generic over view, but is it a too high current or a too high voltage that will damage electronics? I assume it will depend on the component in ...
0
votes
2answers
123 views

Phase difference between voltage source's voltage and current

I tested a simple circuit with AC voltage source and, when I probed the source input for voltage and current, I was surprised to find that they were 180 degrees out of phase. I tested in the LTSpice ...
-3
votes
2answers
91 views

How is amperage “soaked” out of the outlett?

I have some struggles understanding how amperage works. What I understand so far is that amps are the amount of electrons which get pushed by the voltage. But if I have an outlet with 230V~ which is ...
1
vote
2answers
98 views

Why does my current in parallel circuit not add up when I check using a multimeter?

I have a simple circuit 9v connected to 3K resistor coneected to a wire. On this wire, I have two LED's connected in parallel, both leading straight to ground. When I check insert my multimeter ...
1
vote
2answers
61 views

Simple Detect Physical Touch - If object is up against the sensor/object

Definition: Physical touch, meaning the touching of a physical object. Not objectively human in nature, just anything touching / covering the sensor or switch. The above line is included as every ...
0
votes
2answers
67 views

A simple apparatus to detect whether my ear touches a metal plate lying on the floor

For the sake of simplicity, I just want to create a simple apparatus that produces blinks when doing push-up exercises. However, in the future, I will probably combine this system with a digital ...
0
votes
3answers
89 views

Resistor power ratings

Fuses, circuit breakers, transistors, ect... are all rated in amps. Why are resistors rated in watts instead of amps? Does their breakdown/failure include more than just heat?
0
votes
1answer
66 views

Headphones with dual jack, reduced volume

I recently built a pair of headphones and added an audio jack input to both the cans, for convenience of connecting. That would also serve another purpose of letting my girlfriend hear the same music ...
0
votes
1answer
82 views

Converting digital signal to analog

What is simplest way to convert digital signal 1 0 0 1 0 0 1 0 0 (i.e. 1/3 of time its ON and 2/3 of time its off) into sinusoidal signal of same frequency, which can vary from 3 KHz to 6 MHz?
0
votes
2answers
99 views

Can capacitor charge to higher voltage than source provides?

Hi I played with some basic circuits in lushprojects.com simulator and came up with this one that surprised me - when the capacitor C1 is charged for the first time by pressing the SW1 switch the ...
1
vote
1answer
208 views

AVR switch best practice

After reading a lot of posts (here and on the web), I am a bit confused. All I want to do is to get the best practice of push button connection to AVR. I have 2 "sections" to my question. the first ...
1
vote
1answer
159 views

Basic transistor switch

I'm just an amatuer working with some electronics at home. I am trying to use an NPN transistor as a switch. 9v on the Emitter, 6v as the control on the Base to activate the switch, and I'm going to ...
1
vote
0answers
52 views

Solving the equation for Common Drain

So I've designed an all NMOS amplifier to further voltage amplify the 5V max output of an Opamp to 24V rails. I used a Common Source at the very end so I'll have a very low output Impedance. Of ...
0
votes
2answers
77 views

How to properly use ESD protection wristbands

I've looked at other articles on EE stack exchange about ESD precautions. I would like to use a wristband for precaution with microcontrollers. Where am I grounding my wristband to? Do I ground ...
4
votes
7answers
3k views

How can voltage burn out an LED?

I understand how a current higher than what the LED is rated for can burn out an LED, but how does something equivalent happen with voltage? If the correct current is on an LED but the voltage is too ...
3
votes
1answer
78 views

How can you build a floating two-port VCVS?

I have a control voltage at one point in a circuit which I need to duplicate at various other points (3 or 4, if I remember correctly). I'd like to use one potentiometer to control these voltages, so ...
0
votes
2answers
71 views

DC Motor: Difference between E and k?

I'm studying for an exam, and have come across a question I don't. really understand The question gives us a back-emf constant and asks for a rated back-emf. Now I know that the back-emf constant is ...
0
votes
0answers
44 views

Calculate lower-bound for the total average power

I'm studying for an exam and have come across a question question about power lower-bound. In my lectures we have gone through AC peak voltages, \$\sqrt{2}\cdot V_{RMS}\$, I'm not sure if it's related ...
-1
votes
2answers
162 views

How a transistor works?

I know this question is asked a lot and answered well in many posts, however, I'm still confused. A switch transistor works by using a semiconductor to pass the current from an emitter to a ...
1
vote
1answer
514 views

calculate Amp Hours when voltage is given

I'm trying to wrap my head around how exactly Amp Hours work. I have been trying to figure out this question for a while now, but can't seem to find the information that I need. This is the ...
2
votes
2answers
600 views

Where exactly does the ground line go in an AC-DC power supply?

I'm working in the United States. I'm looking into working with mains power, and I cannot for the life of me figure out where the ground line connects. For example, a simple power regulator from mains ...
0
votes
1answer
117 views

Why does oscilloscope show large amplitude when I touch the probe?

When I touch the probe I see a 50Hz sine wave with an amplitude of about 100V from peak to peak. I understand that 50Hz is the mains hum picked up through my body, which acts as an antenna, but where ...
0
votes
3answers
90 views

If we put a led light into a oscillating current, will it blink?

Sorry for the misleading title cause I have no electronic knowledge. It is a simple question. This is the circuit diagram. In case you don't see clearly, it is XOR GATE. My question is what will ...
0
votes
4answers
107 views

How to get started with microcontrollers? [closed]

My point is not to start a flame war, or have an opinion based fight. I really just need advice based off of my experience. I am pretty experienced with using an arduino, I understand C, & C++ ...
1
vote
2answers
4k views

When to use a 1/4 Watt resistor vs 1/2 Watt resistor

I have never understood the difference between 1/4 & 1/2 watt resistors, and in all of my EE lab courses I have always just used 1/4 Watt resistors. When does one use 1/2 Watt resistors and what ...
0
votes
2answers
77 views

Why is current different in 2 identical parallel branches of my circuit?

I'm trying to build the classic thermoregulated fans for an IT cabinet, and I'm struggling with some weird phenomenon. Here is my circuit: simulate this circuit – Schematic created using ...