# Tag Info

### Wemos D1 dies in current sensing project

Why did you insert diodes in CT sensor? The burden resistor is also too big ... Begin with a low value ~ 20 Ohm ... And if the voltage input to ADC is too big, use an attenuator (2 resistors). One ...
• 4,990

### Connecting/wiring MEMS mic breakout to 3.5mm audio jack and reading from it?

The laptop has a TRRS headset jack. It takes standard TRS for standard stereo headphones without a mic. You can't use TRS plug to feed in a mic signal. You need a TRRS plug for that. Word of advice, ...
• 89.9k

### How to parallel shunt resistors with 4-terminals (Kelvin connection)?

As we know, shunts have the problems of: Temperature coefficient for resistance, Resistance tolerance and paralleling has problems of unequal current sharing and uneven temperature rise. These ...
• 1
Accepted

### Output voltage of a step-down voltage regulator (or buck converter)

You can use various approaches to determine the dc transfer characteristic of a switching regulator. The easiest one, as you documented, uses the inductor volt-second balance implying that the average ...
• 14.6k

### Output voltage of a step-down voltage regulator (or buck converter)

There are two different $V_{L}$ values, one (positive) value during $T_{ON}$ and another (negative) value during $T_{OFF}$. Therefore you cannot treat them as a single variable. However over ...
• 51.4k
Accepted

### Common base amplifier - no gain

The voltage gain in CB amplifiers relies on the impedance ratio of Collector to Emitter just like a negative feedback Op-Amp as the common base provides the bias current. This means the emitter is ...
1 vote

### Latching Comparator Problem

After analyzing on the oscilloscope per recommendation, it looks like there was a bunch of noise on the comparator inputs, and the no-latch condition is a result of transients. I solved the problem ...

### Do conduction electrons recombine with positive donor atoms?

Recombination takes place when electron falls from conduction band to valence band, thus one free electron and one free hole disappear. Jumping of electron from donor dopant atom onto conduction band ...
• 311

### Active inductor

Just a guess, maybe you missed a factor of 2 in the gain of OTA because they are fully differential. If in each stage you miss a factor of 2, then the end result will be 4x smaller than it should.
1 vote

### Common base amplifier - no gain

Here is what I get (same values as OP question). AC analysis ... (V output lowest at -20 dB to -35 dB) TRAN analysis ... same than above, in "time show" ... One can see that the levels are ...
• 4,990
1 vote

### Hole current in p-type semiconductors

It is more complicated than that. At equilibrium, the Fermi level of the semiconductor is equal to the Fermi level of the conductor->so the valence band of the p type semiconductor has the same ...
• 559
1 vote

### Do holes in a semiconductor just move when there is a current going through the semiconductor?

Current is the average flow of a large number of charged particles, sometimes called their drift, due to the many orders of magnitude slower that this speed is for practical currents compared to their ...
• 142k
1 vote

### Do holes in a semiconductor just move when there is a current going through the semiconductor?

Brownian motion applies to thermally excited electrons (even if they're a bit de-located) as well, so holes do "move" stochastically in non-zero temperatures as well. I write "move"...
• 78.3k
Accepted

### Series voltage regulator with Zener diode and BJT - equations to explain the working principles

Opening Summary The circuit is the following (you really should learn to redraw schematics for better reading): simulate this circuit – Schematic created using CircuitLab If you are willing to ...
• 70.3k

### Why is intrinsic carrier density only equal to hole - or electron concentration?

I dont get what you mean .In semiconductors the conductivity of the semiconductor $$\sigma$$ is equal to: $$\sigma = en_{e}\mu _{De}+en_{h}\mu _{Dh}$$ we take into account both the drift of electrons ...
• 559

### Twin-T notch filter with high input impedance and low output impedance using one op-amp

Think of it this way: your final transfer function is of the form: $$H(s)=\dfrac{s^2+1}{s^2+as+1} \tag{1}\label{1}$$ Then, you are using a non-inverting amplifier, so $\eqref{1}$ will have to be the ...
• 17.8k

### Twin-T notch filter with high input impedance and low output impedance using one op-amp

"My intuition tells me that this should be possible, but I struggle to create it." I am afraid that your intuition cannot lead to a solution. Let us assume that the feedback transfer ...
• 22.7k
1 vote

### Is generation and recombination same in extrinsic semiconductors?

Yes but there are constantly more electrons generated by the transition of a electron from the donor level to the conduction band. And as it turns out in thermal equillibrium the rate of generation ...
• 559
1 vote

### Common base amplifier - no gain

Note that if you want something to work, the coupling of the input "transformer" must be "good". This is not, of course, the case when the transformer is "on-air". The ...
• 4,990
1 vote

### High voltage current source improvements

Make sure the two transistors T4 and T5 are in contact with each other, (preferably glued or clamped), to keep the two devices at similar temperatures. That will help their $V_{BE}$ to stay together....
• 8,338

### Is twisting a single ended signal with its own GND really useful?

It strongly helps when done right. Allow me to make a small story arc to explain my answer. The problem Ground planes are good dump-and-forget nodes for return currents at both high and low frequency ...
• 11.1k

### Is twisting a single ended signal with its own GND really useful?

We can distinguish two kinds of coupling, inductive and capacitative. Using balanced twisted pairs helps reduce inductive coupling. But the question is about unbalanced twisted pairs. It turns out ...
• 13.1k

### Is twisting a single ended signal with its own GND really useful?

Yes, it is better. Model the cable as two transmission lines: one representing the differential mode (signal to GND wire), stacked on top of one representing the common mode (GND wire over GND plane)....
• 3,027
1 vote

### How to practically find the amplitude of a high frequency signal?

The signal will be anywhere from ~1-24V p-p and (hopefully) useful within ~0.05Hz to 10MHz, though feel free to tell me if this is a lofty goal. The big issue is the bandwidth of the amplifiers and ...
• 63.7k

### Why does this capacitor make the measured voltage higher than supplied?

Does anyone have an explanation? Yes, this is what will happen when a squarewave input is processed by an RC differentiator: - The output vertical edges are constrained to an amplitude of 3.3 volts ...
• 385k
1 vote

### Is it possible for two MCUs to monitor the same analog voltage signal?

In principle there is no issue provided the source can drive both inputs without excessive error. There are not a lot of valid reasons to do this in a new design (as opposed to something being tacked ...
• 332k

### Are op-amp (LM324) power rails physically connected to their input terminals?

That optical isolator tells me that the designer intended the left half of this circuit to operate completely isolated from the right. That's a good design choice, since the left side is connected to ...
• 8,338
1 vote

### Are op-amp (LM324) power rails physically connected to their input terminals?

Should I connect the neutral line of the AC supply in the op-amp circuit to GNDA? It depends on if you want the design isolated or not. The LM3240 on the left side of the LOC110 should be isolated ...
• 63.7k

The white triangle is the analog common reference net, often called “ground” or “0V”. The black triangle represents a connection to the positive supply rail. The connection of two lines to the black ...
1 vote
Accepted

That appears to be internal to the module, likely +24VDC and 0VDC. If so then you should only need to deal with the pinout on the left.
• 58
Accepted

### Linearity of power amplifiers

Expanding on my earlier comment... When there is excess gain available, NFB (negative feedback) is used to greatly improve linearity with non-linear devices and structures. (The following is from some ...
• 70.3k

### Linearity of power amplifiers

In a circuit, the transistors can be under several sets of conditions, which influence the amplitude and nature of the distortion being generated. If you were to look at the transfer function of a ...
• 60k

### Linearity of power amplifiers

For audio amplifiers, from this link, this is a "try" for one technique used in the pre-driver stage. NB: here without feedback. EDIT: Added simulation (simplified sytem) for NFB. Made with ...
• 4,990
1 vote

### How does current flow when you short base and collector in a current mirror?

Electrons are being injected from the emitter into the base Just to be clear, this implies we are talking about NPN transistors here. there isn't any reverse bias voltage nor forward bias voltage ...
• 13.1k

### Does VGA (video graphics array) carry an analog-modulated digital video signal?

VGA signals are analog RGB. They can be digitized in the monitor and processed digitally, then presented to the display, or used directly on a CRT. What monitors digitize the signal? Later-generation ...
• 40.6k

### Does VGA (video graphics array) carry an analog-modulated digital video signal?

The actual video pins on a VGA connector are red, green, blue, horizontal sync, and vertical sync (there are some digital monitor ID pins, but they don't matter here). Sync is pulses (per line and per ...
• 4,705
1 vote

### Does VGA (video graphics array) carry an analog-modulated digital video signal?

If VGA (video graphics array) is analog, then how is it compatible with a digital monitor? It's not "compatible" by any meaning of the word. (I'd even say: a signal is never compatible ...
• 78.3k