Questions tagged [basic]
Fundamentals of electricity, electronics, components, or theory
414
questions
0
votes
3answers
121 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
101 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
80 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
66 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
3k 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
0answers
36 views
Converting a circuit/ schematic onto a breadboard? electronics basics [closed]
I need to produce a complete breadboard for my coursework but due to missing school (leg injury) I don't understand how to convert my circuit/schematic into a breadboard after trying to look online I'...
0
votes
1answer
31 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 ...
0
votes
0answers
68 views
How to prevent common ground circuits messing with each other
I made an Arduino based 18650 battery tester that has 4 identical circuits that charge and drain.
Testing one battery at a time gives one set of results which I deem to be correct but testing more ...
0
votes
2answers
44 views
Wiring a Potentiometer for a positive voltage
I am attempting to make my own adjustable voltage supply that provides a positive voltage (anywhere from 0 to +200 VDC).
The sections I have devised so far are able to provide 450 VDC, however I need ...
0
votes
4answers
89 views
Alternating voltages on vintage calculator circuit board
I am an electronics novice.
I have a vintage calculator with six secondary wires coming out of its transformer and ending on the board, as shown below:
Using the AC portion of the multimeter, I ...
0
votes
2answers
83 views
220 volt step-down transformer with 6 secondary wires
I am an electronics novice. :)
I opened a working Casio vintage desk calculator (likely from the late 1980s/early 1990s). It has a 220 volt step-down transformer with six secondary wires. The two ...
0
votes
1answer
27 views
Preservation of power when wiring batteries in series - battery life is reduced if load is kept the same
This is really just a "sanity check" type question. Am I correct that if you place two batteries in series, that the battery life is effectively halved relative to just one battery, assuming the load ...
14
votes
6answers
2k views
How does an SR Latch get started [duplicate]
Noob question, but I'm not seeing how an SR latch such as the one in the image can "get started". If each input depends on the output from the other, how can there be two inputs to each gate to set ...
1
vote
3answers
99 views
Help explain op-amp description by Forrest Mims
The following description is from the book Op-Amp IC Circuits by Forrest Mims (2nd edition 1994):
As a newbie, the entire paragraph is counter-intuitive to me. If amplitude is reduced, why is there ...
0
votes
3answers
41 views
Voltage Rating of Capacitor Set Up
A buddy of mine just told me that the set up (linked to the question on Circuit Lab) would be able to handle 500 volts DC, even though each capacitor is rated for 20 volts DC. It was to my ...
0
votes
1answer
53 views
PIR sensor bypass for LED light strip
I don't know that much about electronics, but I was able to put together this PIR module:
(original)
and a LED strip and everything works just fine, when the PIR detects motion, it turns the strip ...
0
votes
3answers
77 views
Electricity path through a 240V heating element
My simple understanding of electricity is that you always need a circuit (from + to -, or from hot to neutral), in order for current to flow.
Now, I recently had to fix my water heater (which is ...
0
votes
1answer
74 views
How can I make a simple circuit to output only after a min input voltage is exceeded?
Here's my problem....
I am setting up a camera system on a motor coach that is designed to trigger separate cameras when blinkers or backup is engaged.
the problem I'm having is the only accessible ...
0
votes
2answers
30 views
Explanation results of RC simulation wih LTspice/Micro-cap
I built a basic schema with resistor, capacitor, ground and a battery in LTspice and MicroCap.
I used transient analysis mode.
I expected to see on a chart decreasing current and increasing voltage ...
1
vote
1answer
97 views
Replacing a 1.5V with a 5V power source
I've got a motor that's driven by a 1.5V battery. The shaft turns slowly and that's the way I'd like after replacing with a USB cable (5V) source.
In the current circuit there's no resisters (just a ...
5
votes
5answers
1k views
How is a series resistor limiting the voltage for a diode?
I try to understand some basic concepts, but I'm stuck with this question.
I have this schematic, with a power supply 9V, a resistor 450ohm and a LED.
Assuming the LED consum 16mA, this resistor have ...
0
votes
4answers
82 views
Why the power supplies limit the amperage?
I'm just learning electronics, and I can't understand something:
If the amperes don't matter in terms of burning the circuit, only voltage, why do phone charges for example have a low current ...
2
votes
2answers
79 views
Ringing seen when a zener diode is used with series diode as a snubber
I am trying to simulate the snubber circuit as given in "A zener with series diode"? there is some ringing seen at ouput.
Here is LT spice ckt:
Simulation result shows some ringing at ...
1
vote
3answers
303 views
IR Detector with two indicating leds
I have basic undestanding of electronics, but I never build anything more then simple one element logic boards. I know how transistor, resistors, and LEDs works, but I having trouble figuring out ...
0
votes
0answers
44 views
Modifying the volume pot in a stereo amplifier
This must be a rather basic question.
I have stereo amplifier with a 30K potentiometer serving as a volume control pot (two of them ganged together, to be precise). The pot is connected as a classic ...
0
votes
0answers
34 views
Capacitive Power Supply Torch
I'm an amateur at electronics circuitry and concepts. I have designed a simple capacitive power supply using few web images and brief lessons. I understand that this type of transformerless power ...
0
votes
0answers
51 views
how is this transformer working with DC? [duplicate]
As I was going through the SMPS circuits online I came across this circuit:
I searched and learned that the transformer steps down or step up only AC power supplies and then converted to DC using ...
0
votes
0answers
65 views
Analogy to explain why an antenna must be (in order) size of wavelength
An antenna has to be sized on the order of the wavelength because we want waves to form. Waves mean, very roughly speaking, different "state" (current, voltage, water level, ...) at different ...
0
votes
2answers
121 views
Multiplication of average voltage and current?
Multiplication of \$V_{rms}\$ and \$I_{rms}\$ gives average power. What things we get if we multiply \$V_{avg}\$ and \$I_{avg}\$??
6
votes
8answers
4k views
What is negative current?
I understand that voltage is relative to ground, so that can be negative.
However, I'm currently looking at current-sensors (ACS712 current sensor) and in the performance characteristics table, it ...
0
votes
1answer
83 views
How do you make an ideal circuit? [closed]
I was reviewing for our class and I can't seem to understand how the book comes up with these answers.
-1
votes
1answer
92 views
Why is the answer .908 W instead of 9.08?
I tried calculating it on my own and end up questioning why 200k * e^-10 becomes .908 W instead of 9.08 which was what I've calculated
0
votes
1answer
84 views
Understanding RF amplification
as general interest I am trying to learn a little about RF, antennas and signal amplification, largely in the context of 2.4 GHz.
I have read about two DIY projects that informed me somewhat:
This ...
0
votes
1answer
52 views
Mapping two buttons press as a 3rd button
I got a cheap controller with only 5 buttons. I thought about soldering a few more in parallel so that pressing any of the additional buttons would trigger some other two buttons simultaneously. Then ...
0
votes
3answers
109 views
So why do battery chargers need two prongs? Why not just one? [closed]
Electricity flows from area of highest electric potential to lowest, I get that. What I don't get is why any battery charger would use two prongs on an outlet (or a few other items of similar purpose)....
0
votes
1answer
56 views
How does this RS-latch with open switches power the lightbulb?
So I'm trying to learn some of the basics in electrical engineering such that I can better understand how computers work and I'm currently reading about circuits with switches, relays, different gates ...
1
vote
3answers
102 views
If energy is drained from a capacitor linearly, does capacitor voltage decrease linearly as well?
If a charged capacitor is connected to a current source and resistor as shown above, the resistor is constantly consuming 0.001J/s. If you were to make an energy-time graph of the capacitor, you would ...
1
vote
1answer
142 views
Calculating energy absorbed by an element
I need your help to understand the solution to the given question where energy absorbed needs to be calculated with the given graphs of the current and voltage through the element. Please help explain ...
5
votes
5answers
2k views
How can a circuit not have a neutral?
I've been making plans to install a NEMA 6-50 outlet in my garage, but I don't understand how it can not have a neutral, and instead have two hots (at 120v each) and a ground.
What completes the ...
0
votes
2answers
240 views
nodal analysis, current direction
Right, first the diagram, I tried using the schematic function,but it never actually added the schematic.
I picked this because it illustrates my confusion in the simplest schematic I could find.
We'...
1
vote
1answer
108 views
What Resistor to use between Source and an IC
I'm trying to make a clock, and as part of that I need to power some IC's. To give a specific example I'm looking at the TI SN74HC163 4 bit counter. After some searching around, I found myself ...
1
vote
5answers
232 views
When you connect two batteries in series, why doesn't the middle short?
When you connect two batteries in series, why doesn't the middle short? The connection between the positive terminal on one battery and the negative terminal on the other battery has no load, so ...
0
votes
0answers
42 views
Why does no current flow when GND of one battery is connected to VCC of other battery? [duplicate]
I have enough experience with electronics to design and solder working circuits. I never quite understood though why circuits must be closed for current to flow.
I alway understood electrical current ...
2
votes
3answers
55 views
Infrared Receiver - Simple questions regarding data sheet and basic electronics
I've purchased a 36 kHz IR receiver (TSOP38436) but I'm still learning about electronics and I'm not sure how to connect this to my micro controller (Arduino). (Also, I'm using 36 kHz instead of the ...
3
votes
2answers
168 views
Does resistor placement change power dissipation in simple LED circuit?
Does the power dissipation in an LED and resistor change depending on the resistor placement?
Let's assume the following:
Supply Voltage: 3.3v (DC)
LED Forward Voltage: 2.1v
Resistor: 330 Ohm
I ...
0
votes
1answer
60 views
Kirchhoff Voltage Law in a two port network
In a tutorial about h parameters of a two port network, I find the below snippet in the image unable to grasp. According to KVL, the total voltage in a loop is the algebraic sum of the individual ...
0
votes
0answers
60 views
PC Racing Pedals
I have very limited knowledge of electrical engineering and mechanics (I'm hoping to learn) so please forgive me if this is a stupid/noobish question.
I've been thinking about making a steering wheel ...
2
votes
1answer
333 views
Confusion about current flow
I'm trying to understand how the charging of a plate capacitor works which lead me to question my understanding of current flow. In many explanations, it is said that the voltage source pulls the ...
-1
votes
2answers
69 views
How can I determine the output in this circuit? [closed]
I have such circuit:
simulate this circuit – Schematic created using CircuitLab
Vin is either equal to Vcc or to 0.
How do I go about determining Vout?
