# Questions tagged [calculation]

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86 views

### Find resistor combinations with specific values

I have quite a few resistors but occasionally I run into a situation where I need some specific value I don't have. in those cases I just select a a starting point (more or less at random) and then ...
44 views

### What is the laser power and nm required to cut a row of paper with these specifications? [closed]

Here are my specifics. I am looking at quickly cutting a wet-paper-like material approximately 0.2 inches thick. The material stands up on its own and is separated approximately 0.33 inches apart each....
114 views

### IR Blaster Resistor Calculation for IR LED (breaking ohm's law?)

We are trying to build IR Blaster based on schematics provided by Tuya. I believe Tuya based IR blasters sells hundred of thousands per month if not millions. So I am quite sure that their schematics ...
• 55
49 views

### How to calculate the PLL sweep time?

How can I calculate the sweep time of a PLL for a given bandwidth and a frequency span and setted step? Let say: Span 30MHz Bandwidth 30KHz Steps 200KHz Edit: So lets say we want to sweep from a start ...
• 75
43 views

### Achieved SNR is different than the simulation results

I have designed a transimpedance amplifier as follows: Based on the simulation, I should get around 58 dB for SNR @3MHz: But what I achieved in my experimental results is as follows: Supply voltage ...
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34 views

### How to predict the efficiency of a very low speed Railgun Actuator/Lorentz Force Actuator?

Well, I read somewhere that the slower the railgun is, the higher its efficiency, so I started trying to find out what would be the efficiency of a railgun actuator to move a heavy object (3000kg) at ...
• 182
60 views

### How to calculate the time constant for an attenuation of specific frequencies in a Lock-in Amp?

I am new to the signal processing field, so I am studying what I can and trying to figure stuff out, but I have found one piece of information I really cannot find mentioned anywhere, yet seems very ...
88 views

### How to improve mosfet switching timing?

I am a hobbyist and I am not a native so bear with me please. I was looking for a fast mosfet and by looking at some datasheets I noticed that switching time is not a constant parameter like this one: ...
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1 vote
43 views

### Trying to figure out rise/fall times for different load conditions

I have a device that requires a certain rise/fall time for its input clock. It specs a .7ns rise and fall time with a 20% to 80% measurement at a Cin=6pf. I should note that the spec rise/fall time ...
• 217
179 views

### "Inverting op-amp" circuit calculations using the general feedback formula

I managed to derive the "non-inverting op-amp" circuit using equations from the general formula of negative feedback. Unfortunately, I could not calculate the "inverting op-amp" ...
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1 vote
39 views

### How to calculate values for current and voltage limiting resistors in variable power supply?

I have an assignment, where I have to calculate the values for a current limiting resistor (R3) and a voltage limiting resistor (R14) for a variable power supply. The input voltage to the circuit is ...
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108 views

### How to calculate current limiter resistor when voltage regulator is involved?

I'm designing my first PCB and I'm not sure if the diagram I found on a datasheet is complete. For what I have read, there should be a resistor between R1 and the transistor Tr1. I have followed this ...
49 views

### Parallel circuit calculations [closed]

This is definitely a very simple question for those in this community but I’m in a bit of a jam here. I did a lab where we simply measured the current, voltage and resistance on a low voltage trainer. ...
1 vote
132 views

### Fundamentals of electrical circuits. Practice problem 16.13 Network Stability [closed]

I have this question from my Electrical Electronics textbook. After repeated efforts I still can't manage to solve it and the textbook doesn't provide enough information to be able to solve this ...
178 views

### LED circuit: Need to understand how to calculate

I'm facing to following problem: I need to turn on 5 LEDs (2 V, 30 mA) in series from a 12 VDC power supply using a MOSFET (2N7000G in this case). To calculate the resistor this formula was used: 12 V ...
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1 vote
92 views

### Parallel resistors circuit: remove random resistors and from the total resistance know which were removed

This is more of a mathematics question than an electronics one. With this circuit, I want to know the state of the switches above the resistors, without looking at them. The use case is that I have a ...
• 111
229 views

### Base resistor on BC817-40

There are base resistor calculators and multiple questions are answered on the subject of base resistor calculation. However, the BC817-40 I am using from MCC is showing two different gains (HFE1 and ...
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1 vote
106 views

### Differential amplifier, calculation of differential and common gain

Maybe someone can help and knows how to calculate the differential gain and common-mode gain in a differential amplifier. Will the formula for differential gain be Ad=Rc/2Re, i.e. in my case 50/40=1....
82 views

### Voltage regulator circuit calculations (zener diodes, transistors)

The circuit given in the following Figure is a voltage regulator which is used to supply a constant voltage. It has the following properties: Vin = 20V, Rs = 1 kΩ, R1 = 200 Ω, R2 = 800 Ω, R3 = 2 KΩ, ...
90 views

### Bypass Capacitor

This is a very general question, how to calculate the capacitance needed for a bypass capacitor? Is there a rule of thumb because I usually find values like 0.1uF for high-frequency bypass caps.
28 views

### Six LED Strips 24 V with battery - runtime?

I bought six 250 cm long addressable 24 V LED flexible tubes from Sunliteleds.com According to the producer it uses 28.8 W/m 2.5 meters x 28.8 W = 72 W / Strip So if I use a battery with 10.4 Ah at 24 ...
97 views

### LED Matrix Calculation

I am new to electrical engineering and want to build an LED 4x4 cube. The schematic is below. I need to know how much power I need if all LEDs are on at once. The LEDs I use use an average of 2.8V and ...
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51 views

### How can I calculate the right capacitance value if I have voltage, current, watts and power factor?

I have test results. As we can see, there is a lot of information about voltage, current, watts, capacitance, etc. I have tried to calculate the capacitance value (Cap./Ind.) in the picture, but I ...
50 views

### Calculating JFET stats for a constant current source [duplicate]

I need to find a constant current source for a variable LM317 current regulator (schematic below), and I would like to know which JFETs to use. Can somebody let me know how much current I need and ...
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67 views

### Calculation of unity level (0dB) after gained VCA

Basically I'm controlling a VCA (AS2164) with my Arduino through a 10 bit DAC. All is working well. The VCA output is then gained x 3.3 though an op amp, which in my calculator gives a 10dB boost. The ...
106 views

### Can I calculate beta by using the quiescent point and a voltage divider?

How can I calculate beta with only the data in the image? Q is the quiescent point. I've tried with the basics Vcc formulas, but since it doesn't provide any value for Vcc I could not proceed.
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119 views

### What would be the AWG (American Wire Gauge) standard for my wire 1 x 0.75 rm?

I have been trying to figure out my wire gauge standard in AWG format. I bought a coil (100 meters) of wire and the info written on the package is: 1 x 0.75 rm. I understand the 1 in here represents ...
57 views

### How do I calculate the area 1.5cm away from a LED with a 120 degree beam?

I have a SMD2835 IR LED with dimensions of 0.28cm X 0.35cm and beam angle of 120 degrees. How do I calculate the irradiation area if it is e.g 1.5cm away?
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1 vote
162 views

### Crystal capacitor selection equation

So I've recently discovered that when a crystal oscillator says "20pF", it does not mean "use 20pF caps". (Despite that the design I made under that assumption appears to work.) ...
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1 vote
111 views

### Determine derivative time of real PID controller

I need help determining the derivative time of a real PID controller. Above me is an ideal PID controller. In my case I have another resistor (let us say R0) before R1 and Cd serial. How do I now get ...
71 views

### Estimating junction temperature

I made a measurement using thermocouple to measure the case temperature of my TO-220 linear regulator (L7809). I'll be using degrees celsius for all temperature units and degree Celsius/Watt for all ...
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213 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 ...
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1 vote
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### 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 ...
438 views

### Finding frequency response of inductive EMI sensor

I'm building an EMI sensor and trying to understand how it's done with the Elektrosluch. Here's the full schematic but this is the part I'm concerned about: simulate this circuit – Schematic ...
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228 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 ...
869 views

### How to get the velocity with an acceleration sensor (ADXL345)?

I want to calculate the speed with the help of an acceleration sensor, such as a ADXL345. I thought that it should be integrated, but according to the information that I have received, it seems that ...
67 views

### Why is the output of OPAMP coming as 2.239V? [duplicate]

What formula can be used to get this output? I tried using superposition theorem but the output is not coming the same. Considering V1 off and V3 at 3V : V- = 3V (2k/5.32k) = 1.128V Considering V3 off ...
101 views

### Limiting the output voltage of a boost converter

I have a boost converter TPS61288 which can boost the input upto 18v. Adjustment of the output voltage is done via a potentiometer to the feedback of pin of the converter. 18v is dangerous for my ...
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115 views

### 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 ...
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156 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 * ...
469 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 ...
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228 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 ...
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228 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
245 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 ...
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8k 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 ...
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104 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 ...
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1k 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