Fundamentals of electricity, electronics, components, or theory

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1answer
50 views

Unable to make a pot work correctly

I have a board I salvaged from a joystick that uses potentiometers to measure the location of the arms. On the PCB a edge pin and the center pin are wired together. I would like to connect the pots to ...
0
votes
2answers
54 views

Simple transistor motor driver does not work properly?

The transistor gets hot to the touch and the motor will continue to run when I disconnect the transistors base from 9v+ (I am trying to make sure the circuit works before I hook it up to an arduino). ...
3
votes
4answers
2k views

Why is capacitor a linear element?

Why is a capacitor a linear device? One property for linearity is that the capacitance or some such parameter must not change with voltage or current. Is this enough to make a device linear? A few ...
6
votes
2answers
106 views

Is there any generalized symbol for an electrolytic or electroplating cell?

Is there any symbol for an electrolytic cell? An electroplating cell, for instance? (There are commonly used symbol for electrochemical cell (battery symbol). But symbol for electrolytic cell not ...
0
votes
2answers
167 views

How does a 700W PSU deliver so much power when most wall sockets are limited to about 20 amps?

I will be using a computer power supply to power a car audio amp for a project. The amp is 500w and my PSU is 750w. I never considered it until now, but how does the PSU deliver this? P=VI so 750w=...
0
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4answers
115 views

Where do these grounding wires go? [duplicate]

In the following schematic the two Vss pins where are supposed to be the grounding pins don't connect to anything. Does this mean that the circuit is self-grounding (if that's even a thing)? I'm ...
11
votes
4answers
1k views

Rocket launcher circuit design

I'm building a model rocket launcher with my son. The circuit is very simple as you can see. We want to add a buzzer and a LED/bulb when it is turned on as a warning to stay clear of the rocket. How ...
0
votes
1answer
104 views

How to calculate the output impedance of this circuit?

This is a hybrid-pi model of a BJT, and I want to know its output impedance: simulate this circuit – Schematic created using CircuitLab I know that I should short the input ports, place ...
2
votes
1answer
46 views

Conditions for Thevenin and Norton non-existance

It's not clear to me when a Thevenin or Norton equivalent cannot be produced for a given linear circuit. Can anyone help me with a clear definition? Thanks!!
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1answer
56 views

Why Can't I get a Smooth Sine Curve in PSPICE

I am trying to simulate a Volume Control Circuit in PSPice Student Edition. I am unable to see a smooth sine curve at the output. Could you check my circuit. Find the Schematic below Thanks
-1
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3answers
61 views

Voltage across Capacitor and Inductor with DC Voltage and Current source

As we know, capacitors and inductors are most important components in circuit design. I am just curious about how they will behave when connected across voltage or current source as per below image ...
0
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2answers
44 views

Understanding id-Ugs and id-Uds graph of a nMOSFET

I'm so sorry posting such a horrible-looking picture, but I really cannot found pictures similar to it online and/or in English! If you found one, please let me know and I'll replace it immediately! ...
0
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2answers
68 views

Ambient LED Project

I'm working on mounting LED strips to my entertainment set up and part of it involves mounting strips to the back of my TV. I want to power the LEDs via a USB port found on the back of my TV. I'm ...
1
vote
2answers
77 views

How does logisim differ from redstone and real life circuitry?

I recently developed an interest building circuitry systems. It started in Minecraft and then grew when I picked up a micro controller from Radio shack to build an RC car with. Obviously I'm most ...
0
votes
1answer
81 views

When do I need a resistor during LED flashing? [duplicate]

My goal is to flash a few white LED in serial using 9V battery. Here are the specifications of this LED. As I saw the Forward Voltage is 3.4V, but what does it really mean? Can't I plug this LED ...
-2
votes
3answers
98 views

DUO LED controlled by one MCU pin

I'm having trouble controlling red/green LED. I need to control it from my MCU with one pin. The pin can pull-up or pull-down and the LEDs can be with common cathode or anode. I'm flexible on that. ...
3
votes
1answer
77 views

Complex number \$e^{jk\pi} = (-1)^k\$

I know that \$e^{jk2\pi}\$ or \$e^{\mathrm{integer}}\$ will give you 1, but I can't find the proof for why \$e^{jk\pi} = (-1)^k\$. Can someone please explain how \$e^{jk\pi} = (-1)^k\$? Does it ...
0
votes
1answer
62 views

Sensing a touch of a metal

Assume there is a piece of metal. I would like to identify, with a microcontroller, if another metallic object is touching this piece. I want to apply this for a smart hook that "knows" if a ...
0
votes
1answer
101 views

Transistor delay switch equal to a SPDT Relay

I have a circuit I need the functionality of a SPDT switch that is flipped a couple of seconds after power is applied. It is just switching data lines on a USB port so there is no current being ...
0
votes
1answer
115 views

If this element is unidirectional or bidirectional ? (see the image)

Below the I-V characteristics of two elements .Is these elements are unidirectional or bidirectional ?
0
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1answer
34 views

questions about open circuit, pull up resistor and MOSFET selection

Please let me ask 3 questions about meaning of open circuit, calculation of pull up resistor value and selection of MOSFET. I'm trying to understand how to use the TPS3808G33 reset IC and the ...
0
votes
2answers
62 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
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2answers
44 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
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1answer
57 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 ...
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votes
5answers
188 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
38 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
98 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 ? (...
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votes
1answer
134 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
75 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
79 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
428 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 ...
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3answers
99 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 ...
3
votes
3answers
490 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 ...
4
votes
2answers
465 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
56 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
94 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
113 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
27 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
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2answers
128 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
83 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
60 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
89 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
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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
88 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
2k 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
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2answers
214 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 ...
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votes
2answers
96 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 ...
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vote
2answers
120 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
107 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 ...