8 votes
Accepted

Response of diode circuit

I'll try to explain at least some of Peter's point. Let's look at the circuit you have (I am going to redraw it, so be prepared to verify my work): simulate this circuit – Schematic created ...
  • 73k
6 votes

What is the importance of R1 connected in this circuit?

If \$R_{1} = 0\ \Omega \$, and \$V\!R_{1}\$ is adjusted to \$0\ \Omega \$, then the current through the DIAC and the gate of the TRIAC would be too high, causing one or both to be destroyed.
  • 3,694
5 votes
Accepted

Factorize generic transfer function

How can I factor de denominator to the form (s−z1)(s−z2) in order to find the poles of this "generic" transfer function? (1), (2) and (4) answered together: - $$\dfrac{1}{1 +sB +s^2A^2}\...
  • 396k
5 votes

What is the importance of R1 connected in this circuit?

R1 limits the maximum current into the TRIAC gate when VR1 is at 0 Ω. Because it is only about 1% of VR, it has very little effect on the brightness adjustment range.
  • 13.4k
4 votes

Does the L/C-shunt vs C-shunt/L order of an L-match matter?

\$\color{red}{\text{There was a(n unintended) mistake, please see the edit!}}\$ Feel free to downvote. In the first picture you're not showing the input impedance but, if it is accounted for then the ...
4 votes

What is the importance of R1 connected in this circuit?

R1 gives you finer control. Suppose the ideal range of total resistance is 900-1k ohms. You can get that control with a single 1k variable resistor, but you only would use 10% of the pots possible ...
  • 4,236
4 votes

Why is this an example of actuator?

Actuator is one of those poorly defined words. In a narrow dictionary definition, I think you would be right. But I can understand where your teacher is coming from. He has generalised an actuator to ...
  • 145k
3 votes
Accepted

Phasor of transfer function

For all 2nd order of forms: $$\frac{a_2s^2+a_1s+a_0}{b_2s^2+b_1s+b_0}$$ Set \$\omega_{_0}=\sqrt{\frac{b_0}{b_2}}\$ and \$Q=\frac{\sqrt{b_2 \,b_0}}{b_1}\$ and find the following equivalent: $$\begin{...
  • 73k
3 votes

Guitar amplifier emits a continuous beep, which pitch vary depending on "bass" and "gain" knobs. Finding what's wrong in the circuit

Is there an easy fix to it? Fault finding on this circuit should be easy; you have a pre-amp circuit board and, it appears you have a power amp circuit board set deeper into the picture and in the ...
  • 396k
3 votes

3 dB frequency of first-order active high-pass filter

Calculate the magnitude of \$T(s = j\omega)\$ when it is not acting as a filter (which is as \$\omega \to \infty\$ for a high pass filter). $$|T(j\omega)| = \left|-\frac{R_2}{R_1}\right| \times \frac{|...
  • 7,298
2 votes

RC differentiator / RC integrator explanation

Let's assume the second resistor in the first circuit and the second capacitor in the second circuit are not there, it will make it easier to understand. In the integrator the capacitor starts out ...
  • 6,694
2 votes

3 dB frequency of first-order active high-pass filter

How can I get 3 dB frequency from transfer function? It's simpler than that; the half power point (commonly know as the -3 dB point) is when: - $$R_1 = X_{C}$$. And we know that \$X_{C} = \dfrac{1}{\...
  • 396k
2 votes

Response of diode circuit

Ignore the Ground symbol. The Vi supply is floating relative to Ground so there will be no current flowing between the Vi supply and Ground.
2 votes

Input impedance of op-amp

Apply a test voltage Vx at the input node and calculate the current Ix. Then, Vx/Ix is the input impedance. It turns out to be R1 in your case. You can approach such problems by setting V+ = V- (for ...
2 votes

How to figure out the direction of current and polarity of a circuit element?

You can use KCL to find the direction and magnitude of the current by inspection, then use Ohm's law and the Passive Sign Convention to find the direction of the voltage across the resistor. Since ...
2 votes

Guitar amplifier emits a continuous beep, which pitch vary depending on "bass" and "gain" knobs. Finding what's wrong in the circuit

It is also possible that one of the components has become microphonic . To Quote the Wikipedia article Guitar amplifiers that incorporate the electronic chassis into the same cabinet as the speaker ...
2 votes

Why is this an example of actuator?

I suspect this was not a statement that it is an actuator, but it was a question how it could be an actuator. "to actuate" from the Cambridge dictionary to make a machine work or be the ...
  • 6,646
1 vote

What is the best technique to find out which diode is conducting and which diode is cut-off in the circuit?

The standard method, which doesn't rely on any tricks or circuit-specific simplification, is to make four assumptions: Both conducting D1 conducting, D2 not conducting D1 not conducting, D2 ...
1 vote
Accepted

What is the best technique to find out which diode is conducting and which diode is cut-off in the circuit?

Look for simplifications. For instance, in your first circuit Vc is -3 volts and, quite simply this can be made to be 0 volts if 3 volts is added to Va and Vb. Then, whichever of Va and Vb is the ...
  • 396k
1 vote

Phasor of transfer function

The correct way to do the transformation is to set \$s=j\omega \$. $$s=\sigma +j\omega$$ So $$H_{1}(s)=H_{1}(\sigma, j\omega)$$ Signals that are represented where \$\sigma<0\$ are called ...
  • 3,694
1 vote

Why is this an example of actuator?

The LED has two signals that could be considered a controlled variable (output signal): 1) the colour, and 2) the intensity. The colour is fixed by the band-gap energy as is the voltage drop across ...
  • 3,694
1 vote

3 dB frequency of first-order active high-pass filter

From the transfer function DC gain is 1 so
1 vote

Nodal analysis with LEDs

It depends at which level of accuracy you want to carry out your analysis. If by "nodal analysis" you mean "linear nodal analysis", the thing they usually teach at undergraduate EE ...
1 vote

RC differentiator / RC integrator explanation (input waveform is square wave, triangular wave, sine wave)

If you understood the differentiator output (you said you did) then maybe this will help: - In other words, they are both the same circuit but with different reference points on their nodes so, what ...
  • 396k

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