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# 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 ...
847 views

### Comparator with hysteresis calculation

I'm trying to calculate the hysteresis of the comparator using currents but something isn't right. I'd like a little help to find the hysteresis thresholds without the simplified equations. simulate ...
1 vote
34 views

### MOV parameters understanding and capacitance

I want to add a MOV to the input of my circuit. I came across the following MOV. The specs I require will be the following: Max voltage 300V AC rms Surge voltage 1.4kV Response time 8/20us I have ...
1 vote
43 views

### How to find the terminal voltage of a series generator given output power and EMF?

A 12 kW, 120 V DC series generator has a series field resistance of 0.05 Ω. The generated EMF is 135 V when the generator delivers the rated load at its rated terminal voltage. The armature resistance ...
1 vote
48 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 ...
1 vote
154 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
171 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
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 ...
1 vote
105 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 ...
1 vote
154 views

### How to calculate the resistor value necessary for the columns 8x8 led matrix?

I am building an 8x8 led matrix using 5mm LEDs (3.2V, 20mA). I connect it to the arduino UNO through the I2C using the GPIO expander MCP23017. The circuit is as follows: A matrix column is made up of ...
1 vote
107 views

### DC motor, confusion in specification about Current

So, I am trying to build a little robot mower, and getting all parts. So I recently buyed two DC 12V motors, here is the specs: Now I am trying to calculate how big or which battery should I use, and ...
1 vote
44 views

### Heater - how to define power needed taking into account air thermal dissipation

My objective is to heat a liquid inside a bottle. I have a air gap of 2 cm between the bottle and the heating element (resistive layers). The heater and the bottle is surrounded by a bottle insulator, ...
1 vote
296 views

### Calculating Antenna Directivity Numerically

The equation for peak directivity of an antenna is this (example source) {D = \frac{1 }{ \displaystyle \frac{1 }{4 \pi} \int_{0}^{2\pi} \int_{0}^{\pi} |F(\theta,\phi)|^2 sin(\theta) \, d\theta d\...
1 vote
522 views

### Cable tray width selection as per NEC 392

I would like to ask if anyone know what is the meaning of the letter b used in the formula in the table 392.22 National electrical code 2017 article 392, pic (attached)
46 views

### How to find the right specification of LED corresponding to an incandescent bulb to replace the latter?

I have a motorcycle and its taillight had an incandescent (filament) bulb. The wiring diagram says it's specification was 18W for 12V supply. Now, I want to use an LED (or several) in its place with ...
50 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 * ...
26 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 ?
79 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 ...
85 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 ...
38 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 ...
142 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 ...
74 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 ...
206 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 ...
205 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?
459 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 ...
206 views

### How to get power consumption from datasheet

I am using this stepper motor on my project and am trying to pick a power supply that will be able to supply enough current to all of my components. Looking at the datasheet I'm not sure whether to ...
53 views

### Sanity check inductor calculation

Input: 3.3 V Output: 13 V Output current: 200 mA (actually less then 60 mA but with some headroom) Ambient temp: max 70°C Regulator: LMR62421XSDE/NOPB So my question: What is the smallest inductor I ...
58 views

### Calculation of Power consumption of opamp with positive and negative voltage

I used a single power supply for an op-amp, and I could see the current draw on the power supply. It was easy to determine power consumption using P = V * I. How about dual power supply (+-9V); to ...
134 views

After web researches and a first discussion about general comprehension, I am a bit lost with the load frequency calculation: I see a design which uses two 33pF external capacitors (C1 and C2),with a ...
315 views

### Meaning of Input Leakage Current vs Shutdown Current and Quiescent Current

I am looking at an IC load switch that has values for Quiescent Current, Shutdown Current, and Leakage Current. My understanding is that Quiescent Current is current drawn by the IC in the "on&...
271 views

### Relationship between plating thickness, surface area, and ampere-hours

I am reading a PDF titled Electrochemistry for the Electronics Industry. I am having a hard time understanding the relationship between metals and the Ah (ampere-hour) relationship. For the ...
102 views

### How to make sense of the math behind differential opamp

My first question here! So, I'm designing a simple fully differential amplifier. The final target will be to implement a low pass filter (but I'm not there yet). Although all seems perfectly fine in ...
99 views

### Project circuit current consumption calculation

I'd like to calculate how much my project circuit is drawing for estimating the duration of my battery. My circuit consists of a near-real time sensor which is measuring and sensing some data over ...
54 views

### How do I solve this? Can someone give an explanation?

I don't understand how to calculate the timings for trigger and reset. The answers are 394.1ms & 11.3s respectively. But I don't know the explanation behind it.
73 views

### how to calculate C for lm7809?

I need to use a LM7809 to reduce 12-14V to 9V , the device is using 40mA at normal state when I search google for application circuit - I got all kind of valus for Cin , Cout. use this datasheet ...
43 views

### Calculation of the resistors values in a voltage divider

I'm working on a circuit where a 3.3v flash memory, which comunicate with SPI protocol, has to be interfaced to an 8-bit PIC microcontroller working at 5v. For the MISO signal there should not be any ...
I have this circuit. I'm trying to find the $I_{3}, U_{3}, P_{3}$. For the nonlinear element I have this volt-ampere characteristics: $I_{3} = 3U_{3}^2 -U_{3}$. That's what I am doing. Using the ...