Questions tagged [circuits]
The circuits tag has no usage guidance.
236 questions
42
votes
6
answers
14k
views
Why does my circuit work on a breadboard, but not on a perfboard? I am new to soldering
I'm a total beginner when it comes to soldering, and recently I've been trying (and failing) to solder together a simple circuit I put together for a Raspberry Pi sensor.
Although it works fine on ...
24
votes
3
answers
9k
views
What went wrong with my DIY project?
I have been teaching my son the basics of electronics by taking apart his old toys. We got to the level where we can fix things and put them back together. Last weekend we spent several hours putting ...
- 437
13
votes
14
answers
7k
views
What are some practical examples of a constant current source?
Please don't state the obvious that nothing is a perfect constant current source. And please do not give examples of how to create them from components.
I looked at this SE Q/A which stated the ...
- 257
13
votes
2
answers
69k
views
Different voltage sources in parallel
I realize connecting two different voltage sources in parallel is a contradiction (in an ideal circuit). But if I were to connect this in practice and measure the voltage across points A and B, what ...
- 889
8
votes
5
answers
9k
views
How do I build an electromagnet?
I want to make an electromagnet that can lift a paper clip off of the ground from a short distance (probably 7 to 8 inches). I naively thought of making an electromagnet as a simple task (because of ...
- 99
8
votes
3
answers
2k
views
In the context of a differentiator circuit, what is a “current-sensing resistor”?
I’m reading through The Art of Electronics and am puzzled by the use of the term “current-sensing resistor” as it pertains to differentiator circuits. In the above figure, the author explains that a ...
- 115
7
votes
2
answers
2k
views
What is the circuit symbol for a triple gang potentiometer?
What is the circuit symbol for a triple gang potentiometer?
I've found one possibility for dual gang potentiometers:
(Image source: Components101 - Different Types Of Potentiometers And How To Use ...
- 417
7
votes
3
answers
2k
views
Paradox: potentiometer short circuits between tracks which never touch
I can solder and use basic features of multimeter so excuse my ignorance.
This is driving me crazy, this a potentiometer from speakers which lost left channel sound. I disconnected the volume control (...
- 71
6
votes
8
answers
4k
views
How does an ideal op amp amplify a voltage input when the voltage difference is 0?
I am a first year Electrical Engineering student. Next week I have my exams on Op Amps and their applications and such.
While looking at the op amps, there was always this one this that was confusing ...
- 63
6
votes
6
answers
3k
views
Charging of capacitor in RC circuit
When a capacitor is charged in a first order RC circuit, it charges exponentially. I understand this behavior via equations. But can anyone explain the physical reason?
- 219
6
votes
2
answers
2k
views
If there exists a cascade of op amps, does the previous op amp's slew rate affect the later op amp's slew rates?
All op amps used are the same Texas Instrument LM348n. The datasheet says the op amp has a nominal slew rate of 0.5 V/µs, but gives no tolerance.
I have a square signal with an amplitude of 500 mV ...
5
votes
9
answers
3k
views
"Circuits" - A convenient teaching tool?
At school, we are taught that electricity requires a complete circuit for current to flow.
We are later taught that current flows from areas of high voltage to lower voltage.
So, current can always ...
- 445
5
votes
4
answers
3k
views
How can I control 8 LEDs using only 5 pins of a microcontroller?
How can I control 8 LEDs using only 5 pins of a microcontroller without using any shift registers or I/O expanders?
By "controlling" I mean turning an LED or a set of LEDs on or off, not ...
- 105
5
votes
4
answers
1k
views
Averaging thermistor readings
I have 9 thermistors arranged in a grid, and I want to average the readings from these thermistors without code (that is, average them in a circuit rather than reading all the values into a ...
5
votes
5
answers
1k
views
Boolean Logic - Realization with using only 4 NAND gates
I am currently preparing the next semester of my program at university and I am stuck at a question of the "Digital Circuits" class.
Here is the task:
[...] pump P1 runs when the fill-level ...
- 53
4
votes
3
answers
1k
views
Potential difference and current flow
I've been taught that electrons move from cathode to the anode (negative and positive). But what happens when I apply positive voltages at +10V at one end of the circuit and +6V at the other? How ...
- 889
4
votes
1
answer
3k
views
Fourier Transform vs. Laplace Transform?
The question arose to me earlier, and I never really understood it..
What is the difference between fourier transform and laplace transform in terms of analyzing an overall circuit? I don't quite ...
- 91
4
votes
4
answers
633
views
Capacitor function in a flip flop circuit
I'm new to electronics and I'm trying to figure out the following circuit.
The circuit turns on one of the leds when one button is clicked, if the other is clicked then the current light is turned off ...
- 141
3
votes
6
answers
1k
views
Finding the voltage of a simple circuit
I'm trying to understand the solution of a circuit wrote by my professor. The problem asks to find the voltage across A and B in the following circuit:
The solution provided is the following (where || ...
- 87
3
votes
5
answers
305
views
Usage of input voltages in ideal op-amp
Why is the difference between inverting and non-inverting voltages in an ideal op-amp equal to zero in many problems? I can't seem to get that.
Let's say that if the difference voltage equals zero, ...
- 41
3
votes
2
answers
1k
views
Electronic circuit troubleshooting resin - is it normal?
I have just started my first electronics troubleshooting project of trying to fix our family's toaster. One of the first things I learned was that capacitors tend to be commonly faulty parts of a ...
- 41
3
votes
3
answers
361
views
Using complex impedance
Any help getting the answer shown here?
I have tried adding the complex impedance of L and R in series and then adding that to C in parallel. I'm not super sure about that last step, and then ...
3
votes
2
answers
840
views
Math behind pull-up resistors
I have a question about the the math behind of pull-up resistors and how they work. I don't have any experience in the Electric Engineering field so it's probably a basic question.
I saw many ...
- 41
3
votes
1
answer
11k
views
How to take Time Measurements using LT Spice
I've been fooling around with LT spice .MEAS feature for a while now and I just can't seem to determine how to take the time measurements I need for an assignment.
I can look at the time values on ...
3
votes
1
answer
629
views
Old tachometer rectifier(?) components
I'm trying to reverse engineer the intermediate circuitry of a 1960s vintage marine tachometer made by a now defunct firm called Airguide. Airguide referred to the black box as a "transmitter.&...
- 63
3
votes
1
answer
165
views
What does this strikethrough on the arrow mean? is it not bi-directional?
I'm trying to find out if the main DSP core can communicate with an external DSP via I2S . I'm not sure what that strike-through means.
3
votes
1
answer
198
views
Why is V1 in picture outputting zero? In particular what is the role of R3?
I'm just tinkering around trying to better understand the roles of various resistors in opamp circuits and was surprised by this result.
- 81
3
votes
3
answers
4k
views
Circuit To Measure Phase difference
Is there any classical analog circuit to measure the phase difference between two analog signals ( especially sinusoidal signals )?
I want to measure the phase difference between two sinusoid signals ...
- 43
3
votes
1
answer
3k
views
How to solve combination circuits? [closed]
We were asked to find the total current and voltage, and also the individual currents and voltages of each resistor.
Please teach me the steps for solving each of the circuits, and if you have any ...
3
votes
2
answers
548
views
KVL On A Circuit With 2 Voltage Sources
I want to apply Kirchhoff's Voltage Law on the circuit showed below. When I apply it, I form this equation : $$-20 + Vx - 3Vx - 6i = 0$$
However, my book forms this equation:
$$ Vx + 3Vx + 6i - 20 ...
- 147
3
votes
2
answers
5k
views
Find equivalent resistance at terminals a-b and c-d in the given circuit
I tried delta-wye transformation, which hasn't worked for me. Plus, I don't understand how to solve for two different pair of terminals, all problems before this had only one pair of terminals.
- 33
2
votes
6
answers
4k
views
Single LED connected in parallel to conducting wire does not light up
LED connected in series to resistor. All is well.
This doesn't work.
Neither does this.
This would be the schematic diagram.
simulate this circuit – Schematic created using CircuitLab
Why ...
- 123
2
votes
3
answers
790
views
Electrical counterpart: Logical not
I'm building a circuit where I must receive a signal from a logical not. More specifically, I'm looking for a real-life electrical circuit element/component that provides power/signal on the output ...
- 45
2
votes
3
answers
711
views
Do the resistors affect every component of the circuit?
I've noticed something strange in the circuits schemes I saw in a book.
Let's say that there is an LED and it's anode is connected to a 5V power source, and it's cathode is connected to ground.
...
- 231
2
votes
3
answers
231
views
Simple examples of higher order circuits and the cause of non linearity
In my previous question, I learned that resistance, capacitance, and inductance are not enough to capture the behavior of all circuits. This led me to the question, what are some examples of 'simple' ...
- 137
2
votes
4
answers
171
views
Do ALUs perform all/most N operations before running through the multiplexer?
I'm doing some self-study on hardware and currently implementing an ALU. The way I'm designing it is such that I have an N:1 MUX (N inputs yield a single output (16 bit number) based on selector bits)....
- 33
2
votes
2
answers
298
views
Why can both parties feel static electricity
Sorry I'm new to electrical engineering, trying to clear up some confusion on how static electricty works and why both people feel a shock when touched by static electricity.
When creating a circuit, ...
- 135
2
votes
3
answers
108
views
Transient analysis of first order circuit
For the attached problem, I am getting the signs wrong.Here I have considered the inductor voltage signs as such because after closing the switch, less current would flow through the inductor but ...
- 45
2
votes
2
answers
608
views
Finding the transfer function and damping coefficient an LCR circuit
I am trying to determine the general transfer function of the following circuit.
Shouldn’t the transfer function just be \$R + \frac{Z_CZ_L}{(Z_C+Z_L)}\$? I am trying to then use the transfer ...
- 21
2
votes
1
answer
155
views
Beginner circuit multimeter reads strange current
I have constructed the following very simple circuit.
I would like to measure the current running through the circuit with my multimeter. I break the circuit as follows and connect the red lead to ...
- 289
2
votes
1
answer
1k
views
Elements' order in a circuit
I was reading about source transformations and came across an example where there was a change in the order of two series elements, is this always possible? The same for in parallel elements but that ...
user201599
2
votes
2
answers
184
views
How to use an Arduino to turn a supply voltage to another device on and off?
The Question:
With what kind of extra components if needed, can I use to output a signal out of one of the Arduino pins to turn the voltage on and off to a device. The goal is to output a HIGH or LOW ...
- 31
2
votes
1
answer
178
views
Appropriate circuit for activating relays
I am trying to use two G5V-2-DC5 relays to switch four wires at the same time between two different outputs. All signals are 5 V. I've gotten this to work fine with a simple physical switch but want ...
- 151
2
votes
3
answers
171
views
AC through inductance only
How will we have a current through a pure inductive coil connected with ac power supply? I am confused because the induced emf will be equal to the applied voltage but opposite in direction,
\$emf = -...
- 21
2
votes
1
answer
9k
views
Diode-connected PMOS
Im currently a year 1 electrical engineering student. May I ask, for a diode-connected PMOS (gate connected to drain), why is |Vsd| = |Vgd| ?
- 21
2
votes
1
answer
302
views
Should I use a voltage regulator in tandem with a voltage divider to get 12V, 5V, and 3V from 14V power supply?
I am assembling a circuit that requires 12V, 5V, and 3V. I have a 14V power supply. To create the 12V, 5V, and 3V rails, should I use a 12V voltage regulator and then multiple voltage dividers to get ...
- 33
2
votes
1
answer
73
views
understanding circuit protection
Ok so i'm hoping that someone can explain to me in basic terms: in an un-fused circuit what could actually cause an electrical component to be damaged by current flow. I'll explain the reason for my ...
- 21
2
votes
1
answer
3k
views
RL circuit: How to determine the equivalent resistance of the circuit?
So I'm working on an RL circuit and the solution is stated to be that R1 and R3 are in series, but I didn't think that was the case because they don't have the same current through them. Given ...
2
votes
0
answers
190
views
Problem with battery power circuit
I am a 14 years old boy and I am currently making a MacroPad with a 3.7V battery and a charging circuit but powering the circuit with a battery does not seem to work. I also have made some ...
- 357
2
votes
0
answers
279
views
Designing the first stage (common emitter) of an amplifier that will drive an 8 ohm speaker
I have to design an amplifier (can be one stage or multiple thought I am thinking multiple) that will drive an 8-ohm speaker and have a gain of at least 10 V/V (about 20 dB) given Vcc = 9 V. It also ...
