Questions tagged [basic]
Fundamentals of electricity, electronics, components, or theory
454
questions
0
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2answers
45 views
Why is my voltmeter output incorrect
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 ...
0
votes
2answers
88 views
Will Kirchoff's voltage law work in a vacuum
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 ...
0
votes
1answer
31 views
resistor combination circuit
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 ...
0
votes
1answer
26 views
Multisim Multimeter showing blank reading (--------)
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 ...
0
votes
3answers
107 views
Why does the impedance of a parallel RLC circuit approach infinity at resonance?
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 ...
1
vote
2answers
100 views
Why does pin numbering and placement (in general) appears to be done so haphazardly to the uninformed person (me)?
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 ...
3
votes
1answer
132 views
Filter w/ seemingly higher output voltage than input?
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 ...
6
votes
4answers
294 views
Simple power on delay for 3.4v-5v serial device being powered by 5volt VCC
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 ...
0
votes
4answers
145 views
What is the relationship between electrical resistance and heat generation? [duplicate]
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) ...
0
votes
1answer
57 views
I want to understand this audio input to LED output simple circuit
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 ...
0
votes
1answer
113 views
How do I ground my power supply?
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 ...
1
vote
0answers
42 views
Noob Question, 74HC240 and Solar Cells
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 ...
5
votes
4answers
878 views
How do I determine whether a switch can handle the power/current in a circuit?
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 ...
0
votes
2answers
46 views
Basic Series/Parallel connection understanding
I am just starting out with electronics and I have understood that there is something fundemental I just cant seem to figure out about parallel and series connections. I am having a lot of trouble ...
3
votes
1answer
92 views
Is it safe to cut these wires?
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 (...
1
vote
1answer
111 views
Circuit with 1 diode in parallel with a resistor
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 ...
0
votes
5answers
220 views
Basic BJT current mirror : … so the collector-base voltage of Q2 is also zero?
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 ...
2
votes
2answers
69 views
Please help me with finding if I need to add a resistor to my circuit
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 ...
0
votes
1answer
59 views
Resistor across output?
I'm trying to learn about gates.Why is a resistor connected parallel across the output?
1
vote
2answers
80 views
RC Low Pass filter, capacitor in series or in parallel?
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 ...
0
votes
2answers
164 views
2
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3answers
221 views
Why does the voltage drop across an LED matter when determining an appropriate resistor value?
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?
1
vote
1answer
500 views
Wiring RGB Strip LEDs w/ just positive and negative wire [closed]
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 ...
0
votes
1answer
61 views
steady state voltage in capacitor network
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 ...
0
votes
2answers
47 views
Resonant frequency and maximum signal width
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 ...
1
vote
0answers
87 views
Audio amplifier circuit explanation
Recently, I am working with amplifier circuits but circuits available online for an op-amp have some extra components with respect to what we learn in textbooks.
I know the basic amplifier components ...
3
votes
1answer
58 views
Current Divider with dependent source
I'm currently studying electronics for the first time. The objetive of this exercise is to calculate the current I and the dissipated power in the dependent source. However, I'm having a hard time ...
0
votes
1answer
34 views
Trigger two circuits with single SPST switch
I'm an electronics noob willing to learn. So I have a door bell that looks like it is wired like this:
And I've bought a fancy 3V battery powered device that is intended to be wired simply like this:...
1
vote
2answers
80 views
Output characteristics of transistor
Why is the slope of output characteristics of transistor in CE configuration more than that of CB configuration??
0
votes
1answer
177 views
Find the Thevenin's equivalent of a circuit between nodes A and B
My class had come to discuss the Thevenin's theorem and we stumbled upon this particular problem which quite confuses me in a way that what I found is different than what my lecturer taught us. So, ...
2
votes
1answer
100 views
Power supply module on breadboard giving too much voltage
I'm currently following the tutorial "Electronics Fun Kit" by ELEGOO. The goal is to connect the power supply module with the breadboard in order to provide a 3.3V / 5 V source.
After connecting the ...
0
votes
1answer
43 views
(Basic) How to connect the ground in this schematic to a breadboard?
I just want to know how do I connect the ground in the circuit. I know how to connect DC source but I'm confused on how to connect the ground. I have adept knowledge about the concept of ground, I ...
1
vote
0answers
67 views
Testing a LM111P comparator
I have the LM111P voltage comparator (datasheet.)
I am learning my ropes with electronics, so I am moving thru the easiest topics to more complicated ones. If I understand correctly, when I provide ...
1
vote
0answers
53 views
Separation of channels in simple audio LED VU meter
I'm trying to build a very simple VU meter based on LEDs and transistors. I used this tutorial as a base - basically I copied the LED array setup but replaced the input with full bridge rectifier. My ...
3
votes
5answers
2k views
Why is it called Wired-OR when it is functioning as Wired-NOR?
Inputs: Base of bjts
Output: black node
When at least one of the inputs is HIGH the output is LOW.
This is clearly NOR. Then why everyone calls it Wired-OR?
2
votes
2answers
100 views
Op amp outside resistive network
Usually I don't care about algebra and just focus on the functionality. However, below circuit form appeared so many times in last few days in op amps that I thought of memorizing it by heart.
From ...
0
votes
3answers
151 views
Two charged capacitors connected in series
simulate this circuit – Schematic created using CircuitLab
The circuit has the initial condition as shown in figure. What will Vfinal be when SW3 and SW2 are open but SW1 is closed.
2
votes
2answers
59 views
How is it possible to force \$v(t)=\cos(t)\$ as voltage input to a fully discharged capacitor?
Let initial charge on capacitor \$Q=0\$ and say \$v(t)=\cos(t)\$ is applied for one period(\$2\pi\$ seconds) across the capacitor. Then the current will be \$i(t) = C\cos(t+\pi/2)\$. Clearly the ...
0
votes
3answers
79 views
In an equation like i(t) = CdV/dt, is “V” the cause and “i” the effect?
In mechanics, almost all the time, force is the cause and acceleration the effect. If you apply a net force on an object, an acceleration can be observed. However this seems not that straightforward ...
0
votes
2answers
43 views
How does difference in loads affect current draw
This is a side question to 487370/limit-charging-current-to-a-smartphone. Hopefully it will clear the confusion in my head.
Say we start at 5.5V with a series resistor of 1 ohm, that will leave 5V ...
0
votes
2answers
84 views
Transformers and wattmeters
This is, probably, a very silly question, but I was thinking:
If you have a watt meter and you connect a step up transformer with the lower voltage side attached attached to it (both the voltage and ...
0
votes
2answers
67 views
Thevenin's voltage
I'm trying to solve and exercise (see picture) where I'm supposed to find the voltage drop between 2 points in a circuit, using Thevenin theorem. I removed the resistance between those two points.
...
1
vote
4answers
76 views
How do I find the missing equation?
This is my first post here, hope you all doing well. I'm a CS student, having my first class on circuits. I've been given this problem (see picture) where I'm asked to find V2. I'm missing one ...
0
votes
3answers
140 views
How Does Kirchoff's Law Make Sense
I understand the algebra, and I can also use Kirchoff's Law in calculation.
But I struggle to understand how it makes sense logically.
The law states, that the sum of the currents entering a ...
0
votes
3answers
120 views
Why are LEDs so tolerant of voltage?
My electricity knowledge is about high-school level or so. Just about enough to be dangerous...
Back when I was a kid I used to play around with 4.5V DC power sources, buttons, switches, relays and ...
0
votes
5answers
174 views
Will a capacitor draw charge/current if it's not feeding a load?
I have a number of capacitors connected in parallel, as in the following circuit:
simulate this circuit – Schematic created using CircuitLab
If the switch is open, will the caps still draw ...
0
votes
0answers
67 views
8000 Amps across a 1 A diode for 0.2 uS
Assuming that the diode is rated for 20 kV and the pulse is only 250 V, will a 250 V 8 kA pulse that lasts 0.2 uS break a 20 kV 1 A diode? This also assumes that the diode recieves 10 of these pulses ...
9
votes
4answers
4k views
Do capacitors waste power as heat or whatever on AC?
Capacitors store energy then give it back once required. A perfect capacitor is nearly lossless on DC power because you only fill it once then it keeps energy in it until you discharge it so no power ...
0
votes
1answer
37 views
How to calculate voltage of these nodes
How exactly does one calculate the voltage of the marked nodes and arrive at the numbers in the picture (1.75 and 1.628)? I fail when trying. :(
simulate this circuit – Schematic created using ...
0
votes
1answer
33 views
Comparing transformer set ups
Is it practical to connect the output of a ferrite-core 1:40 transformer in series with the input of a 1:6 ferrite-core transformer as a means of acquiring 240 V?What would the pitfalls be of this ...
