# Questions tagged [calculation]

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### What is the current industry practice regarding the impact of current-limiting fuses on arc flash calculations?

Suppose you have a panel. The arc flash incident energy for this panel is computed based largely on the available short-circuit current (SCCA) to the panel, and the protective devices upstream of the ...
• 17.3k
34 views

### HB100 Doppler sensor calculation

I have a question about the first circuit schematics. I calculated the second circuit's fcutLow and fcutHigh frequencies like this: f2CutHigh = 1/(2 * π * 1M * 100p) = 1.6 kHz f2CutLow = 1/(2 * π * ...
22 views

### How to calculate sum of jitter

I have two clock generator and i have connected them in series. If we assume they have jitter of x, what would be sum of jitter how can i calculate that ?
59 views

### Calculation of pull-up resistor for open-drain output - multiple loads

Link to voltage supervisor Link to AND gate I would like to drive an open-drain output to multiple (5) loads, all of the same type. I calculated the pull-up resistor range needed and wanted to double ...
• 189
1 vote
182 views

### Need help with validation of the design of a capacitance sensor array for soil moisture measurement

Product Description The device is a soil moisture sensing and analysis device that uses capacitance sensing technology to help manage soil moisture in your garden. One probe set at the bottom of the ...
219 views

### How best to perform calculation on voltage and feed output to segmented display?

I'm working on an audio electronics project that uses frequency modulation. A potentiometer will control the tempo/modulation speed, and I'd like to convert the voltage value to a triple-digit value ...
1 vote
51 views

### How to find resistance, inductance, and capacitance of a load/device

I'm planning to make a proper simulation of a circuit. Before the simulation, I need information about the load (resistance, inductance, and capacitance). Example: the load is a CPU. range of wattage ...
• 23
1 vote
166 views

### How to convert cordless tool to corded tool "properly"?

This question is the closest thing that I found similar to my needs, but it is still quite far from the answer I need. I have 2 cordless power drills, a 12V green Bosch and an 18V DeWalt. Their ...
• 171
39 views

### Calculation of tolerance of a resistor for voltage sensing

I want to calculate the tolerance of resistor accurately to run a simulation to simulate accuracy of voltage sensor. The resistor I am using is CRCW0603330RFKEA - 330 Ω from Vishay and I can't see ...
• 251
96 views

### Heating element testing - calculation

I have a 3-phase, 30 kW, 480 V AC heating element. I’m trying to utilize resistance as an aid for predictive failure. Using Ohm’s law calculation 480 times 480 equals 230400. 230400 divided by 30000 W ...
1 vote
94 views

### MOSFET thermal calculation

In my application I will use a MOSFET as an on-off switch. There won't be a PWM signal. I want to calculate the temperature rise of the MOSFET but I am confused. Continuous drain current is 100 A, RDS(...
151 views

### How to calculate the maximum current a wire can handle?

Is there a formula for calculating the maximum current a wire can conduct without melting? I found one: I = αd^(3/2) in which I = fusing current, d = wire diameter in inches, and α = a constant ...
59 views

### How to define initial conditions for complex RC circuit?

I need to calculate $U_2 (t)$. See the circuit below: Given $E$, $R_1$, $R_2$, $C_1$, $C_2$, $C_3$. The first Kirchhoff's rule: $$i_1 = i_2 + i_3 = i_4$$ Now find the all currents:  ...
• 159
77 views

### Op-amp plus diodes: resistors' values calculation

I am tasked with following: R1, R3 and R3 are to be calculated so that the diodes work in forward bias. Assuming the diodes have a voltage drop of 0.7 V and the op-amp is ideal I have calculated that ...
• 41
122 views

### Do carbon resistors generate heat in a properly working circuit?

Do resistors in a circuit generate heat based on their resistance value? Can anybody explain how resistors drop voltage without generating heat?
37 views

### Simulate powerbank's disconnected state

There is a powerbank which has (among others) an USB-A port. The powerbank can be turned on with two methods: Pushing its button Connecting a load to either of its ports In any case, the bank will ...
• 561
89 views

### What is a "charge cycle" of a lead-acid battery?

I'm trying to develop an algorithm that would roughly estimate the health of a lead-acid battery tied to an inverter backup system. It seems that my 200 Ah battery pack stays at 100% state of charge (...
• 71
97 views

### Calculation single phase and three load connected at the same time to three phase network

I have a single phase load (90 A 230 V) and 2 three phase loads (7 kW 400 V 3 phase/9 kW 400 V 3ph+N) connected at the same time to a three phase network. How the 3 phase calculations (line current of ...
96 views

### Frequency of a 555 timer

I want to use a 555 timer (as I have them at hand) to give me a 2MHz clock for an AY-3-8500. I have two questions really: While the 555 may not be ideal, is it possible? How to I calculate the ...
1 vote
42 views

### Getting Discharge Safety from a Battery

I would like to calculate the battery runtime for an ESP32, using a 18650 battery with 2600 mAh (Datasheet). When I am using a calculator such as this one, it requires me to put in a discharge safety ...
56 views

### Rewinding a 6 V DC motor and decreasing inrush current

I have a small simple 6 V DC motor and I would like to rewind its rotor. The motor has 2 magnets. The rotor has 3 poles to wind. Normally each part has 169 turns of winding with 0.15 mm2 copper wire. ...
1 vote
219 views

### Using the superposition principle when there is a current source in the circuit

At the top is the main circuit. Below that is the circuit formed by removing the 5 A current source (We remove that for using the superposition principle and this is the first step). I don't ...
105 views

### Rewriting piecewise voltage function using Heaviside?

Recently I've had an idea to create an assignment where we have low-pass filter connected to the voltage source which is described by piecewise function. I've already dealt with periodic functions ...
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1 vote
128 views

### Calculating PID gains analytically on a first order plant (RL Load) - is this possible?

Edit: Just for a bit of context. I have another higher order plant model that has a derivative branch in its control. I thought I'd just implement PID control on the current in an RL load I have just ...
1 vote
133 views

### Calculating steady-state temperature for electrically heated wire

I am working on a program aimed at finding optimal parameters (voltages and feed rates) for a hot wire foam cutter. One starting problem that has to be solved before even attempting to evaluate heat ...
1 vote
84 views

### Filter coefficients and filter calculation methods

I'm trying to figure out the R and C elements for a second-order Bessel filter approximation. Unfortunately, in the below calculations the quality factor is negative, so it is wrong? (I checked by ...
121 views

### Calculating hysteresis with an open drain comparator

I have a circuit as follows which will compare an input voltage to a 2.5 V (actually 2.3 V) reference. In one of the documents, it mentions that the feedback resistor must be 100 × Rpullup. If my ...
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285 views

### How do I calculate the electrical power of a BLDC motor?

I used a current sensor to measure the current of one of the motor phase lines (Iphase or Iline?), and used a voltage sensor to measure the voltage between two motor phase lines (Vline-line). With ...
1 vote
61 views

### Can the secondary voltage of this old transformer be derived?

Images are of an unknown "4808" PCB-mounted transformer. It has an open 240 VAC primary. Data: EI48 core, around 12-15VA. The center-tapped secondary is 15Ω-CT-15Ω and 1.6H-CT-1.6H according ...
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170 views

### Simple circuit of 4.2 V lithium-ion to 3 V use

I have a lithium-ion battery of 4.2 V maximum voltage. I want to power a 1 W LED at 3 V. What size resistor do I need?
• 11
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### 0 dB Bode plot as a reference in an academic paper

I want to compare the calculated bode plot of an inverting op-amp with the simulated one, on the 1 mHz-200 kHz spectrum. As expected, theoretically there is no stray capacitance on the circuit above, ...
196 views

### Why does 277/480V 600A 3 phase = 500 kVA and not 288 kVA?

According to an electrical engineer 277/480 V, 600 A, 3-phase is 500 kVA. I would like to understand more about why that is. I always thought 277 V x 1.73 = 480 V (and that's where 277/480 label comes ...
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125 views

### How to calculate RMS noise from datasheet?

I am using an AD9833 DDS as a sine signal source for my circuit. The bandwidth will be 3.5MHz. I would like to calculate the RMS noise of the DDS for my bandwidth. The datasheet has a SNR ...
• 109
113 views

### Simple question on finding Watts and Wrms

I've done a bit of research but can't find the explanation for this problem, at least mathematically. I'm calculating W and Wrms of an audio amplifier by knowing output Vpeak and Load resistance. It's ...
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53 views

### Effective resistance integrator circuit

I've encountered the following circuit and I'm puzzled about the effective resistance that the opamp will see. I know that R1 is in parallel with R2+R3, so this would be easily answered by R1*(R2+R3)/...
• 61
87 views

### Crystal oscillator error due to ppm

In this link, the accepted answer states that there may be an error of 1 minute per month if the crystal ppm is 20ppm. Can someone help me with the math of how the error of 1 minute is arrived?
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1 vote
65 views

### CCM Boost PFC avg rms current

I follow the "Fundamentals of Power Electronics-3rd Edition" to derive the below equation. Now, I would like to derive the Transistor Average, ， and I follow the book formula, but my answer ...
• 533
65 views

### Pull up / pull down resistor value

Wanting to calculate the value of the pull down resistor for a 555 trigger. For the formula should I use the typical or max trigger current (typ = 0.5 Max = 0.9 μA). I want the calculated value not an ...
• 11
97 views

### Calculating AC Unit Watts

I'm trying to calculate the watts used from my AC unit. Below I am including my sticker label that's on the AC Unit along with a electrical data sheet I found online for my model. So far this is ...
175 views

### I made a darlington transistor in LTspice. But, that has different values from theoretical values

As you may see from title, I made a darlington transistor like this. I set each transistor(Q1 and Q2) to have β = 150. So, total darlington β must have 22500 or thereabouts according to a formula ...
144 views

### LM317... Do we need resistors?

In the circuit below, I replaced LM1117 with LM317. Do I need to add resistors at the output terminal? and how can I calculate the output voltage in this case?
171 views

### Calculation of capacitor of deep trench DRAM

If I know the depth of the trench L, the size of the DRAM node D and the thickness of oxide (say HfO2) T. How can I calculate the capacitor of a trench?
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1 vote
2k views

### How to calculate length needed for heating element (2mm Nickeline/Nichrome wire) to a specified power?

to start off, i dont really understand about electrical engineering. im a mechanical engineering student tasked to continue the project. i dont really understand electrical stuff beside the very basic ...
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391 views

### How do you calculate electrical active (3-phase) power with L1,L2,L3 (I) angles to L1 (U) and L1,L2,L3 (I) and L1,L2,L3-N (U) measurement?

I get from a Landis+Ggyr E650 electricity meter data via a serial IR head (62056-21 / D0) about every 20s. This meter provides a lot of data, but not the current actual active power (kW). Some of the ...
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75 views

### Issues with getting UR

I'm trying to get UR5 from this schema, but something is not right. All I have so far
648 views

### Energy calculation using Arduino

How I can calculate accurate energy if I have power, current and voltage values? This is the code of energy calculation, the result's it's wrong so how I can fix that? I want to measure apparent ...
280 views

### Calculate power dissipation of split-supply op amp for sinusoidal input

I want to calculate the total supply current and power dissipation of an op amp in a non-inverting voltage follower configuration with a split supply: simulate this circuit – Schematic created ...
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169 views

### Flyback converter input current

I have solved A and B of this question but i have no idea how to solve C. any help would be apriciated