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Questions tagged [resistance]

A measure of how much a conductor opposes current flowing through it. It can also refer to a part of a circuit, which has a non-negligible resistance value.

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Calculating inner resistance of a linear dipole

I've been stuck on a question for a while now, so I'd really appreciate if you could take a look at this: I'm supposed to calculate the dipole's inner resistance. I've got that E= 15V, R1= 1200 Ohm ...
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93 views

What is the value of the given resistor?

I tried checking with 5 band color code but was unsuccessful. Resistor is blown hence the value cannot be determined using multimeter.
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How to find current through series of potentiometers, and if it is safe for potentiometers? (Arduino)

I have 9 potentiometer with the specs: 10k Ohms and 0.5W I'm using an Arduino Mega, and using it's 5V port output to power these potentiometers in series, and I saw online that the max current this ...
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38 views

measuring resistance on hv transformer

I need to verify the resistance on a HV transformer that receives 208v single phase through terminal 1 and 2, or 240v through terminal 1 and 3 and delivers 4000v through terminal 4. As per the ...
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1answer
75 views

Can a 125mw dual gang pot handle 10w audio output?

I want to build balance control for two audio amplifier circuits, and I want to use dual gang pot. I want to know if I connected it directly to the outputs of the two audio amplifiers circuit then to ...
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36 views

How to evaluate equivalent insulation resistance of two cables?

My guess was that the equivalent insulation resistance of two cables in parallel is same as the equivalent resistance of two resistances in parallel. But instead it is the sum of the two insulation ...
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2answers
94 views

Measuring the resistance of USB car chargers

I have a few USB chargers that are powered through a 12 V car receptacle. I measured their resistance with a multimeter, applying the probes to the contacts of the 12 V input. One of the chargers had ...
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40 views

Voltage and amperage requirements for resistance heating of glass

I am planning to introduce electric heating/boosting in my glass melting furnace. The present temperature of the glass is around 1200 deg C and I need to raise it up to 1300 deg C. I am trying to get ...
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82 views

Can a 3W pot be connected to a 5W LED baton? [closed]

Situation: I got a LED baton and the brightness was higher than required. I added a regular 22k pot in series to it, and achieved lower brightness, but within a few seconds, the pot was burnt. I ...
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180 views

LED Blinking after replace

For clear any mistake, the question is: Why the LED started to blink after being replaced? The goal was to replace the blue leds with red leds, after replacing the leds one of them started to blink, ...
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2answers
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Create a simple resistive heating element on PCB with Altium

I have created a component with a simple pattern using tracks and arcs as shown in the link below. How to Build Custom PCB Heater Elements However, Altium DRC is throwing errors since I have used 2 ...
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2answers
35 views

Powering an IR + RED laser with an Arduino

I am hoping to run a laser diode from an Arduino. The specific one with included data sheets are here: https://industrial.panasonic.com/kr/products/semiconductors/laser/red_infrared/red-and-infrared-...
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Electric heating for glass melting furnace

Some furnaces use electricity for glass melting. Low voltage and high amperage power is passed through the molten glass through 2 molybednum electrodes dipped into the glass. The molten glass acts as ...
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1answer
101 views

How to solder resistance wire?

For the kids of my electronics tinker club, I thought it would be a great experiment to see how the resistance of a wire is proportional to its length. Therefore I made a very simple circuit ...
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2answers
48 views

What should be the output resistance of this source with series diode?

Below shows three sources with open terminals: simulate this circuit – Schematic created using CircuitLab In Figure 1 if we want to calculate the output resistance, according to the linear ...
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3answers
87 views

Basic resistor question for parallel LED circuit

I'm planning on building an LED circuit to place inside a model miniature for wargaming. The circuit would be in parallel as I'd need a really big battery to power up all the LEDs. I wanted to check ...
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2answers
46 views

Am I misunderstanding steady state power disspation calculations?

I am looking at the Littlefuse 5KP series. It says on the datasheet: I am trying to understand how they arrive at \$P_D\$ = 8.0W. Given thermal resistances of 40°C/W or 8.0°C/W, and 100°C ...
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49 views

PC fan speed control

I am making a stir plate out of an old PC fan, variable resistor, and DC power supply from this tutorial. I have two power supply's to choose from, their outputs are: PS1 = 12Vdc, 2A PS2 = 12Vdc, ...
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Logic Circuit Transistor Resistor Values?

Last week, I posted a problem with a logic circuit (Need Help With Transistor Logic Circuit Design), and Analogkid was kind enough to solve it. However, at the time, I didn't realize I still had a ...
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3answers
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How do I determine the range of wire wound adjustable resistor?

I'm looking at buying a 300W tubular adjustable resistor. Like this: https://www.digikey.com/product-detail/en/vishay-dale/RBEA03001R000KFB00/541-10193-ND/9765057 Digikey has four part numbers in ...
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43 views

Path of current and equivalent resistance

In this circuit, the current can flow from node 1 to node 2 through two different paths i.e either thorugh R2 or (R1+R4). Since the current selects the easier path I expect the current to flow from R2 ...
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29 views

Considering power loss in a simple series connection due to cable

A friend and I are struggling on a simple electricity exercise: A heater is connected to a \$U = 230V\$ power network over a copper cable. The cable has a cross-section of \$A = 1.5mm^{2}\$ and a ...
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75 views

Mixing analog audio signals with resistors

I am creating a type of mixer for 2 audio inputs into 1 output so i can use 1 pair of headphones with 2 computers without buying an expensive mixer with a amp Currently i have 1k 1/2W metal resistors ...
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83 views

Which load resistance is connected to generator U2?

I have this op amp and one of the questions says Which load resistance is connected to generator U2? This is my attempt but I can not confirm if it right. No it's not homework, it examples I'm ...
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2answers
74 views

Do rail gun systems require high voltage?

I couldn't justify, as to why most rail-gun examples I found would have high current and high voltage. When the rails & projectile can be designed to have low resistance by varying the volume of ...
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4answers
147 views

Too High Voltage Drop across Transformer's Output

I want to get very high current flow thought secondary winding of transformer on my 3 Ohm load. As I apply high voltage of secondary to the load the voltage across it drops dramatically. Only about 2% ...
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56 views

Difference between horn and power resister?

I have a circuit where my microcontroller is turning off and on a heavy load using a power mosfet (I've also tried it with a mosfet and a relay which yielded the same results). When I use a power ...
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1answer
29 views

Input Resistance and Mid-band Gain of a CE-CE Stage Cascade Amplifier

I am trying to calculate the Input Resistance and Mid-band Gain of a CE-CE stage. Here's what I got so far: I am having some doubts regarding my calculations though. Mainly with the input ...
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1answer
33 views

R series by terminal A in a potentiometer

I have a question to clarify about potentiometers. Maybe the question is something silly or obvious, but I would like clarification because I'm not so sure about it and I need to be so as not to miss ...
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2answers
163 views

Is static negative resistance practically available?

I learned that negative resistance (NR) could be simulated by involving active devices like op-amps and others. I'm interested in the static/absolute NR rather than the differential NR. My question is ...
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3answers
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Measuring a small resistance, ~0.001 ohm

I have a low resistance resistor that I would like to use to measure the current through another circuit, but first I need to accurately determine its resistance. Its data sheet says it is 0.001 ohm +...
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1answer
53 views

How do I calculate total resistance?

As far as I understand, two resistors are connected in parallel if the node at both ends of both resistors are the same. And in series if only one node is the same. But what if between two resistors ...
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1answer
53 views

Resistor's behaviour at high frequencies

Looking at the impedance vs. frequency graph 1) At low-frequencies Z=R and hence it would be a straight line. 2) For mid-frequencies, Z decreases possibly due to capacitance, but I'm not sure ...
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1answer
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Resistance range indicator

I am facing a huge task of checking 1000s (1000s per box and I have nothing less than 20 boxes) of wire wound resistors purchased by my company. I have been assigned to check the resistance value of ...
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2answers
70 views

Is my understanding of current, voltage, and resistance correct?

Im currently a senior in highschool. So I know that voltage is the potential difference per unit charge, or from my understanding the work done to move a unit charge from point a to point b without ...
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139 views

Power absorbed by load resistor

Can someone double-check where's the mistake? The system didn't accept my answer. TASK: Find the maximum power absorbed by the load resistor, knowing that: $$E = 6.6V; R_{1} = 12.1Ω; R_{2} = 14Ω; R_{...
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37 views

What is the parasitic resistance due to an IC package in a mosfet? (or any package)

How much resistance does the package of an IC contribute to the paraistic resitance of a circuit? (most applicable to mosfets)
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1answer
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Series/parallel combination of resistance/capacitance in an RC circuit (wrt LCR meter readings)

I have this equivalent circuit I am working on. I have to find out individual values of all components in it. I can measure resistance, capacitance and impedance of the whole circuit. I am not sure ...
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1answer
65 views

Why the input resistance of a common emitter amplifier is like this?

I am trying to find the input resistance of this BJ common-emitter amplifier: I replace the transistor with the hybrid-pi model It appears clear to me that the input impedance will be \$ R_{in} =...
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2answers
76 views

Conceptual paradox with resistance in loop/node analysis

There are loop/mesh analysis and node analysis corresponding to Kirchhoff’s voltage law (KVL) and Kirchhoff’s current law (KCL), respectively. Let's consider three elements, R,L,C, connected ...
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31 views

Conductivity formula for Metals

Is there any expression for the direct change in conductivity of metals with temperature ? I am aware of change in resistivity with temperature.
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49 views

What is the current through this parallel circuit?

I'm trying to solve the attached circuit for I1 and I2. I think I1 is just 5A but I'm not so sure about I2, I think it might be just 10/5=2A but I'm not sure if the voltage in the top right part is ...
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Problem understanding an exercise regarding impulsions

So, I'm having quite some trouble understanding and solving the following exercise. We're given the following montage We are told that the following square signal (called Vin) is applied Now, we ...
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1answer
45 views

Why is there a minimum input resistance?

I was looking at this multimeter, and it says, Output rate:     0.1 V/A (use with a device having a 1 M-ohm input resistance or higher) Where can I read why this minimum resistance is required? ...
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2answers
203 views

How can I calculate length of wire, given its gauge and resistance?

As the title suggests; I am trying to calculate the length of a wire given its gauge and resistance in ohms per 1000 feet. I also have the amount of voltage drop, which is 1.1 V. ...
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2answers
205 views

Output resistance of MOSFET circuit

I am trying to find the output resistance \$Rout\$ of this circuit consisting of 3 n-type MOSFETs. It is given that all 3 MOSFETs have \$g_m=4 mA/V^2\$ and output resistance \$R_o=100k\Omega\$. ...
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2answers
195 views

How to calculate secondary winding max current output?

I have removed a UPS transformer. It is a Class B Viking transformer. Its primary side has 4 wires coloured black, green, blue and yellow. I found resistance as follows- 1. Black to Green - 17 ohm 2. ...
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122 views

Uses for 49.9Ω resistors? [duplicate]

It seems that both 49.9Ω and 50Ω resistors are a thing: https://www.mouser.co.uk/Passive-Components/Resistors//N-5g9n?P=1z0wnltZ1z0wljo https://www.mouser.co.uk/Passive-Components/Resistors//N-5g9n?P=...
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1answer
77 views

Find potential difference between nodes A and B in circuit below

By KVL and KCL Ix = 4A and Iy=Iz=6A The potential difference between A and B = Va - Vb = 6 +8Ix =38V I don't understand how we calculated the potential difference using KVL and KCL
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3answers
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How can I find out which resistor is short-circuited and can be ignored?

I don't understand how the current flows in the circuit below. How do I deal with the wire between nodes c and a, a and b, g and d. Why is the 5 Ω resistor shorted out? I am having a little trouble ...