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Fundamentals of electricity, electronics, components, or theory

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I'm designing a device (simple 5V LED) that will be powered by a smartphone (via the USB C socket). I am struggling with allowing the phone to be charged at the same time via the same connection. Is ...
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How do I derive an expression for v_o / v_s? This answer fills some gaps but it doesn't tell me how they came up with the expression for V^- (corresponding to -v_d in my notation). ETA: here's what I'...
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I'd like to start generating (and perhaps also capturing) composite video (PAL) signals from a digital source, eg. FPGA. However, while my digital logic/programming skills are covered, I'm lacking a ...
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I'm not understanding Proteus or something I'm doing wrong, and it's really basic, I put a 9v Battery, a Red Led, simple circuit and a 10k resistance, so the led shouldn't turn on right? Well, is ...
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I think I know the answer, but I'm unsure. I'm studying for my FE, and in the practice exam is the following question: An ideal transformer connects a 120-V, 60-Hz voltage source to a load. One ...
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So I had an exam in basic electronics, which I passed but lost a lot of points on one seemingly easy task. "Through the coil is passing a current equal to \$i_L=200\sin(10^5 t + 210°)\$. If R=5 ...
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I want to connect a 12V fan and a motorcontroller to this generic ac to 12v dc power supply. The motorcontroller is pulling around 25 amps, and the fan about 1. I'm just wondering, should i add a ...
Siim's user avatar
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Please help me with this simple circuit, which is creating lots of confusion due to different results from theoretical calculation and SPICE simulation. Ques: In this circuit switch is closed for time ...
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Do the values of resistors matter when I want to use them in series to increase the maximum voltage they can handle? So can I just use a 1 megohm resistor for example that's rated for 200 V and then ...
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I am trying to create some redundancies for a small commercial ice maker to prevent there from ever being a flood in my garage. The ice melts from the ice bin (which holds around 80lbs of ice) ...
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I would like to do a simple undervolatge lockout. I thought a BJT as a switch like this: In normal conditions I would have 30V (and -30 and the othre rail) and 25 mA to 50 mA. These power rails will ...
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I am new to electronic circuits. I built a basic LED circuit on a breadboard to test everything out. It worked as in pictures, but the connections were not stable because the holes were very large. I ...
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There's a bunch of posts about this, but they're all for very specific scenarios. I'm a newbit, and some components, like op amps, require both a positive, and negative voltage. But how do you get ...
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I am watching this tutorial, and topic of parallel circuits came up. In the below image, the combined resistance is 60Ω, which is less than either of its parts (150Ω and 100Ω). I understand how the ...
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I'm currently taking a course in electromagnetism, and I got stuck with this problem: The Problem: All of the resistors and capacitors have the same values, R and C respectively. The circuit is ...
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I am new to using circuit/breadboard simulation apps. When I run the simulation nothings happens. Here is the original schematic. Edit: I'm using 74HC00. Also I learned how to use Virtual Breadboard ...
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I was asked to find the Is current I applied KVL in that loop but my ans is wrong. what concept is wrong on my approach?Why kvl cant be applied on that loop please explain
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I am working on writing a control program for my pellet smoker. I am having an issue with the meat thermometer that came with the smoker. I have a MAXIM 31865 ADC that is connected to a Raspberry Pi. ...
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I am a beginner in Electronics; I am learning the basics and am trying to take up circuitry as a hobby! My query is regarding power supply requirement for any circuit. Take, for example, a circuit to ...
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I am following this video from EEV blog where he talks about calculating heatsinks and I noticed that he does not talk about multiple components sharing a single heatsink. I have lurked around the ...
Joaquin Brandan's user avatar
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a newbie on electronics here. I would like to create a simple RF kit. on transmitter side, only 1 button. on receiver side, if a valid code is received, a relay activates to provide 12VDC to a load. i ...
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I'm doing a replication of vehicle hi/low beam switch in my "lab" and I'm not sure what's the right type of switch for it. It has to have a dedicated on/off switch (the one on the bench ...
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I want to power a computer fan from a 12v motorcycle battery. Disregarding the motorcycle battery being 12.6 volts (not charging), lets say that it's a regulated constant voltage source of 12 volts. ...
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I faced a lot of problems in understanding BJT. I am going to share what works for me. Suppose we take an NPN as the transistor in our case. The emitter base region is forward biased, so electrons ...
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I'm trying to connect an old/possibly broken switch to a light from a 12V battery (very good first question isn't it?). The switch is meant to light Green when ON mode and Red in OFF mode. The schema (...
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So I'm completely new to electrical design. I thought I'd try out the most basic experiment I could think of. Here I hooked up two AA batteries to a breadboard along with a 10 K resistor. When I ...
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Kirchoff's voltage rule tells us that the sum of voltages around a closed loop in a circuit will equal zero. If a battery sits on a table, using KVL and treating air as matter with high resistance ...
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simulate this circuit – Schematic created using CircuitLab This is probably a very stupid question. I am new to electrical engineering in general, I was working with NOT transistor gates in ...
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I am trying to build a simple circuit to back up some hand calculations that I am completing for a project. However I am unable to get a reading on the Multisim multimeter. I have changed the ...
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Pretty new to this stuff so apologies if I get some words wrong. In the book I'm reading they described a parallel circuit with a resistor capacitor and an inductor powered by a current source. They ...
Onye's user avatar
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Be it an ESP development board, an IC controller, even an LED segment number itself, pin placement never seems to follow a logic when it comes to actual numbering, or function. I can't find a simple ...
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I'm working on a simple LC filter as part of an AM radio project. I was intending to use a ferrite antenna (modeled roughly by the voltage source in series w/ inductor which is then connected to a ...
jcu's user avatar
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7 votes
4 answers
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What I am trying to do I am trying to build the most simple as possible circuit to give a 3.4v-5v serial device a 1-2 second power on delay from the embedded Linux device running at 5v that it is ...
Dani's user avatar
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An incandescent light bulb has some amount of resistance (let's say 30 ohms) and generates a large amount of heat. It's my understanding that a resistor with the same amount of resistance (30 ohms) ...
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I'm a newbie in electronics. I watched a youtube video that showed how to activate LEDs using a microphone. It's project #3 at https://youtu.be/zsJ61yJhWVU?t=115 The guy built the circuit on camera ...
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I have a Meanwell GST120A24-P1M +24V power supply (picture below). I want it to power a circuit of mine. Say the circuit is as shown below: one power supply and one resistor. How do I connect the ...
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My idea is to start soldering and I would start with something quite simple. I chose the project (https://cdn.makezine.com/make/08/pummer.pdf), a pummer with solar cell charging up a supercapacitor ...
mant0's user avatar
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8 votes
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I have a switch that has "3A 250VAC" and "5A 125VAC" printed on it, which I imagine are ratings of what the switch can handle, but my understanding that 3A at 250V would be 750W ...
slagroom's user avatar
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I am just starting out with electronics and I have understood that there is something fundamental I just can't seem to figure out about parallel and series connections. I am having a lot of trouble ...
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3 votes
1 answer
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My kid got a face mask with flashing eyes, but there's also some annoying sounds that comes with it. Is it totally safe to cut the white wires or could the awesome flashing lights stop working too (...
tallberg's user avatar
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1 answer
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Sorry if this question has been answered here before, but I just can't seem to find any info on this. A little background. I am currently doing an automotive mechatronics course and, while I know some ...
José Capela's user avatar
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From this schema I don't understand this sentence from here, particulary in section "Basic BJT current mirror" "...If Q1 and Q2 are matched, that is, have substantially the same device ...
user7058377's user avatar
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2 votes
2 answers
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I want to connect 3 4V LED strips in series to a 12V, 1A supply. Each strip requires 250mA current to operate. This makes a total of 750mA required current for all 3 strips. My concern is how should I ...
Nikhil Powar's user avatar
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1 answer
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I'm trying to learn about gates.Why is a resistor connected parallel across the output?
Vinayak Sankar's user avatar
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2 answers
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I've seen 2 variations of the RC low pass filter, sometimes with both the resistor and capacitor in series, and more commonly with the capacitor going straight to ground. What is the difference ...
J.Ramsden's user avatar
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2 answers
409 views

What would be the voltmeter reading in the following circuit?
Puneeth's user avatar
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3 answers
420 views

In determining the voltage dropping resistor, why is the forward voltage of an LED deducted from the supply voltage instead of considering the supply voltage alone?
Samovar maker's user avatar
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1 vote
1 answer
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I'm working on a small project, and I had some leftover strip LEDs lying around. They're just the RGB strip LEDs you can pick up at Five Below. They come with an RGB controller attached to a short USB ...
Darin Beaudreau's user avatar
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simulate this circuit – Schematic created using CircuitLab I have this capacitance network in my circuit and I can't figure out the math behind why the final steady-state value of Vx=0.542v when ...
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I've seen resonant frequency being defined as the point where the input signal is in phase with the output signal (So reactance/susceptance is 0). However conceptually, teaching material seems to link ...
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