Skip to main content
21 votes
Accepted

Cross section of ceramic capacitors

It looks to me like the grinding/polishing has been done fairly well (with more care you could have less scratches), and you're looking at an accurate and undamaged image of the capacitor cross ...
Jack B's user avatar
  • 12.2k
17 votes

Will this mains disconnect circuit work?

Firstly, you are playing with mains electricity. Everything I suggest here is contingent upon you knowing that it could kill you, or someone else. Secondly, altering mains-connected wiring may lay you ...
Simon Fitch's user avatar
  • 37.6k
14 votes

Will this mains disconnect circuit work?

You need a no-volt-release switch, which is designed to do exactly what you want. Like these ones. They are used in industrial machinery to stop motors starting unexpectedly after a power cut. You'll ...
emrys57's user avatar
  • 1,042
12 votes
Accepted

Why is power of a signal equal to square of that signal?

If the signal is represented as a voltage \$v(t)\$ or a current \$i(t)\$ and it is connected to a (1 ohm) resistor, the power dissipated in the resistor is proportional to \$v^2(t)\$ or \$i^2(t)\$. ...
AJN's user avatar
  • 3,881
11 votes

Cross section of ceramic capacitors

I assume the purpose of this exercise is to source capacitors that are OK. Unless you are buying gazillions of the things, and so would have the purchasing clout to make the manufacturer listen, ...
Neil_UK's user avatar
  • 168k
10 votes
Accepted

Why we use conjugate of current than the original phasor in the calculation of Complex Power i-e S=VI*

The voltage and current signals have an angle associated to them, better known as \$\theta_v\$ and \$\theta_i\$, respectively. In terms of power, you want the phase difference between those two ...
Big6's user avatar
  • 5,724
9 votes

What is this Op-Amp Configuration doing?

It's a precision full wave rectifier. Try searching on google for it using those words. Here's one: -
Andy aka's user avatar
  • 462k
8 votes

Why is power of a signal equal to square of that signal?

$$ P = \frac{V^2} R $$ If you're driving a constant resistance then the power is proportional to the square of the voltage. You can rewrite the equation substituting, from Ohm's Law, \$ V = IR \$: $$ ...
Transistor's user avatar
  • 177k
7 votes

What is the purpose of the capacitor in this SMPS circuit?

Essentially this is already said by Rohat Kılıç but you may want to see it written in a less strictly formal way. Without that capacitor it's possible that the circuit finds a stable balance where it ...
Ed Halfsunk's user avatar
6 votes
Accepted

RC Circuit Analysis Direction Changes Formula

The basic constitutive equation for a capacitor is based on these assumed polarities, The equation being, $$i(t)=C\frac{dv}{dt}$$ If you want to define your current as leaving the capacitor then you ...
relayman357's user avatar
  • 3,497
5 votes
Accepted

Will this AM radio receiver work?

It wont work .C4 stops the detector diode from working .Remove C4 by shorting it .R2 is way way to low and will load the tuned circuit meaning no selectivity.Use a high impedence buffer like say a ...
Autistic's user avatar
  • 14.9k
5 votes

What happened to all of the Dynamic Signal Analyzers?

Ah yes, the HP3561 100kHz DSA, I remember it well. The first 'difficult' problem we used it on was the stabilisation of a thermal servo loop. With a characteristic times of minutes, those mHz were ...
Neil_UK's user avatar
  • 168k
5 votes

Battery Charge and Discharge Time

There are numerous errors in your calculations. 50000/0.5 = 100,000 Wh Dividing two dimensionless quantities can't result in a value of Wh. Again: 100,000 x 1.04 = 104,000 Wh And again: 104000/...
Olin Lathrop's user avatar
5 votes

Op-Amp analysis without using op-amp gain

And I know that : $$V_-=V_+$$ This is not true for your circuit. This rule becomes true when you set up a circuit with negative feedback. Your circuit does not use negative feedback, so you can't ...
The Photon's user avatar
  • 131k
5 votes
Accepted

Please explain the purpose of the marked resistors and diode in this transistor relay driver circuit

Before answering, we should know what the function of that circuit is. The function of the above circuit is when \$V_{in}\$ is high, the relay will work closing the switch so the circuit of the ...
NAND's user avatar
  • 498
5 votes

Voltage and current

It is proven only when there is a potential difference current flows in that branch between two nodes ... No, it's not. If there's a resistor between those two nodes, then yes. If there's zero ...
Neil_UK's user avatar
  • 168k
5 votes

What is the purpose of the capacitor in this SMPS circuit?

It's there to accelerate the turn-on of the MOSFET (IRF840). I'm going to try to explain over the start up but still the same thing applies for steady state. When the power is first applied, the gate-...
Rohat Kılıç's user avatar
4 votes

Problems with DC analysis of a PMOS circuit

Your calculation for VG is correct. The correct result for ID is not 0.2126mA. You only have 4.4V total supply voltage. But the resistance is 48K ohms. Therefore the upper bound on the drain ...
user4574's user avatar
  • 12.3k
4 votes
Accepted

Problems with DC analysis of a PMOS circuit

Something is wrong here. The range between the two supplies in 4.4V, but with a 212.6 μA current, the drop across the source and drain resistors is: $$212.6\mathrm{\mu A} \cdot (6000\mathrm{\Omega} + ...
Adam Haun's user avatar
  • 22k
4 votes
Accepted

Order of precedence for parallel operator

It looks like the parallel operator is surprisingly common, and there are precedence rules defined by some sources, but not all. MIT in their courseware suggest using it, and set exam questions on it....
rob's user avatar
  • 56
4 votes

Analysis of Preamp circuit

the purpose of the 0.1 µF input capacitor and the 200 kΩ resistor is not a HP filter, but an AC input coupling; if it was standalone, it would be a high-pass filter with a ~8 Hz cutoff frequency, ...
Marcus Müller's user avatar
4 votes

Rectified Voltage doesn't seem possible

The voltages shown are measured relative to ground, and they are assuming an AC-coupled average-reading multimeter. It's a simple bridge rectifier. The 10nF capacitors are to reduce buzz in the audio ...
Spehro Pefhany's user avatar
4 votes
Accepted

AC analysis of voltage divider CE amplifier - how are non-parallel resistors treated as parallel?

What properties of a power supply make it provide a low-resistance path for AC signals In AC analysis you treat the DC power supply as a short. This is justified by the rule of superposition.
ErikR's user avatar
  • 5,007
4 votes

Series/Parallel Resistor Association

Don't be confused or mislead by the diagonal "wires". Resistors R5 and R6 are tied together at each end, so they are parallel by definition. In my experience it is almost always easier to ...
Nemojack's user avatar
4 votes

Is it possible to ignore Nyquist-Shannon theorem?

I was thinking about accumulating data and then doing some maths on this. How would you figure-out which frequency produced the samples (black dots): - Blue is over-sampled and red is under-sampled. ...
Andy aka's user avatar
  • 462k
4 votes

Best way to transfer indication signal from one STM32 to another STM32

Consider RS-485 between the two. It's easy to do, cheap, and can be made extremely reliable. One of the advantages of RS-485 over CANbus and similar is how easy it is to get RS-485 in and out of ...
jonathanjo's user avatar
  • 14.4k
4 votes
Accepted

Transient circuit analysis with additional source

initial thoughts I don't see any initial conditions being given in your question. Of course, the only possible initial condition would be the voltage across the capacitor. But I don't see it mentioned,...
periblepsis's user avatar
  • 10.3k

Only top scored, non community-wiki answers of a minimum length are eligible