It's a measure of how much an 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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18 views

Cermet potentiometer temperature coefficients

I'm engineering a system that is temperature-sensitive, between ~-10-30C. I've moved to using cermet potentiometers because of their sub-200PPM/C temperature coefficients. If I wire such a pot with ...
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0answers
26 views

Toubleshooting PCB circuit - strange Zener diode behaviour

I have two units of a device which I shall call deviceA and deviceB. DeviceB is malfunctioning. Therefore I compared the resistance values of the same components on the boards of both deviceA and ...
0
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2answers
31 views

Losses in wire with varying cross section along its length

Say I have 5 meters of thick wire (10 sqmm), and for the last couple of centimeters, I have to use a piece of 2.5 sqmm wire for mechanical reasons. When sending a large amount of DC (say, 30 A) ...
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0answers
33 views

Change range of output values of potentiometer

I would like to use a fuel gauge in my car that expects 240 Ohms when the tank is empty and 33 Ohms when full. However, my current fuel sending unit reads 168 Ohms when empty and 34 Ohms when full. ...
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3answers
129 views

Why the diode has higher impact on dc characteristics than ac?

Consider this circuit which consists of a DC bias and an AC source connected with a diode and resistor: Source: Boylestad and Nashley book 11th ed. Using superposition theorem the circuit was ...
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1answer
36 views

dropping a signal voltage proportional to signal

Basically i have a car that im installing at aftermarket ecu in, The tps signal is normally a 0-5v signal (varible resistor on a 5v output from the ecu) that the ecu uses for various things, However ...
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1answer
29 views

Does wire gauge significantly impact the charging rate of smartphones?

This article claims that wire gauge in USB cables significantly impacts the charging rate of smartphones: USB cables have a data wire and a charging wire within the cable itself. Most USB ...
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4answers
119 views

What Happens to Unit If We Divide Two Resistance

My question is very basic. I have a resistance circuit in which two resistances of 2 ohms are connected in parallel. I want to find the equivalent resistance. I know the equivalent resistanve will be ...
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2answers
152 views

What is the resistance of a typical PCB?

What is the typical resistance between two points on a "typical" PCB? Let's say the points are 1mm apart and let's assume a normal office environment. I've noticed that resistors come in many values, ...
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1answer
51 views

Testing Amps And Resistance On PC Case Fan

Context: I'm wanting to tinker around with some mini solar panels to power some old PC case fans I have laying around. I know that case fans are generally 12v so I was thinking of running some 3v ...
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1answer
66 views

AC Wire Resistance

I stumbled across some unexpected data points when measuring the AC resistance of magnet wire. I varied the frequency of the AC voltage and measured the corresponding impedance of half a meter of 32 ...
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0answers
26 views

contact resistance

AZ2150 is a power relay that is rated for 40A at 240VAC. It has a contact resistance of <20milliohms initially. After use they say that typically the contact resistance will be between 20-100 ...
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1answer
40 views

additional resistance required to produce a potential drop

A wire of length 100cm is connected to a cell of emf 2V and negligible internal resistance. The resistance of the wire is 3Ω. The additional resistance required to produce a potential drop of 1 ...
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2answers
67 views

What is the best way to configure an electric fireworks igniter

I've seen a bunch of tutorials on creating a fireworks igniter using, a resistor or a piece of copper wire and a 9 - 12 v battery. Basically you the resistance from the small piece of copper or 1 ohm ...
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4answers
99 views

Why do wider cables have lower resistance if parallel resistors in general increase resistance?

So given two resistors both with resistance R, the resistance they would have in parallel would be R*R/(R+R) right? For large R, R^2 increases like a square and 2R increases linearly, so there must ...
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0answers
25 views

Nichrome or Kanthal wire specs for kiln

I plan to build a kiln that can achieve 1000C - 1100C in temperature. I bought a PID controller and SCR voltage regulator to control the temperature. But I want to know if there is a detailed ...
5
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2answers
161 views

Does the Y-Δ transform suffice for every resistor network?

Suppose I have a (finite of course!) network of resistors only. Is it always possible to calculate the equivalent resistance between any two points using only parallel, series, Y-Δ and Δ-Y (wye-delta ...
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3answers
194 views

Why is the impedance in the parallel resonant circuit maximum at resonance?

Why is the impedance in the parallel resonant circuit maximum at the resonant frequency? For example if we have two resistors in parallel the equivalent resistance is less than the values of the ...
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1answer
63 views

What happens if an electric circuit has 99% resistance? [closed]

What happens if an electric circuit has 99% resistance? What if you let electricity come out of a the negative terminal, and only the tiniest bit of electricity comes back through the positive?
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0answers
25 views

What are resistor actually? [duplicate]

I know that resistor resists flow of electrons from one point to other. I can understand the working of capacitor and inductors which are based on properties of magnetic and electric field . But what ...
2
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2answers
95 views

A theoretical question on probe resistances for a voltage measuring device

As seen in the figure above, a current regulator is providing a constant current looping through the series resistor Rshunt. Input impedance of data acquisition device is 10 GigaOhm. Can we say that ...
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2answers
81 views

How to measure resistance

I have a project to build heating element using silver ink. My specification is the heating element must be in range 2 to 2.6ohm I will design the circuit for the heating element, but have a problem ...
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2answers
62 views

Resistors and capacitors calculation for 555 timer circuit

I am new to electronics and I want to try an experiment. I want to use a 555 timer to create an automatic food dispenser for my aquarium (something like opening a small door when the timer has ...
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4answers
552 views

What is the total resistance of a LED array?

First time poster and a hobby EE enthusiast here. I want to turn on a LED array with a transistor switch and I'm having trouble with determining what will the total resistance on my transistor ...
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0answers
29 views

Calculating DC resistance from p.u. impedance

I need to calculate or approximate the DC resistance of a 208.5 km overhead line which has the following information: impedance per unit on 100 MVA base: R = 0.004 X = 0.047 B = 1.049 Is it even ...
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2answers
55 views

Why do we short the input when calculating the output impedance?

I believe the title says everything about the question. My issue has to to do with the following: Consider a two-port given by: $$V_1 = Z_{11}I_1 + Z_{12}I_2$$ $$V_2 = Z_{21}I_1 + Z_{22}I_2$$ Cleary ...
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4answers
54 views

Why does this circuit give different values for different methods

Is there a rule that I am missing? I need to find the resistance of this circuit: I seem to get different values depending on which way I take the resistors. Is there any rule I am missing when ...
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1answer
58 views

Finding Equivalent Resistance

The question asks to find the equivalent resistance of such a network of resistors. simulate this circuit – Schematic created using CircuitLab I have managed to simplify it down to the ...
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3answers
2k views

Where did these Ohms come from?

I am new to electronics and am tyring to figure out something that is a bit disturbing to me. I am trying to figure out the amount of resistance I need to put in series before an LED, and the equation ...
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2answers
54 views

How does one determine the voltage of a node?

This sounds like a very straightforward question, and probably has an obvious answer. I've read a section in a physics book on electricity, I've read a textbook on DC and this simple concept seems to ...
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1answer
65 views

How do I calculate voltage on a multi-powered DC circuit where all ends go to ground?

I'm writing software that will calculate the correct voltage on each component, given the state that the DC system is currently in (ex. what power sources are on, what relays are open, fuses popped, ...
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3answers
86 views

how to calculate time for timer relay

In the below circuit of Timer Relay, how I can calculate the time for C1 to be fully charged? please don't use regulator, transistor or any other device I just want to use Resistance and want to ...
0
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2answers
34 views

Resistance calculation with specific load

I saw this and it is completely different from my question Resistance calculation My question is below. I know that Ohms law is E=IR but I don't know how to use this in a real circuit. if I have 12 ...
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5answers
353 views

Measuring a huge resistance on low voltage

I was thinking on this theoretical experiment for a while, but nothing useful came into my mind. We have a "resistor" (rather a material like plastic) with a resistance expected to be very high, say ...
2
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2answers
65 views

How to find the power delivered to the load?

I'm trying to solve a homework problem to find the power delivered to the 10Ω load. So far I found the total resistance, which is 12Ω. And I think I have the right formula to work out the power, ...
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1answer
43 views

Checking damaged resistance

I have a battery charger on which a resistor is damaged and I don't know how much resistance was that. Is there any way to check damaged resistor's value? And also please let know that if a resistor ...
1
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2answers
48 views

Voltage Divider, increasing resistor value for solar tracker

I am working on a solar tracking device based on arduino and I am using LDR's (Light Dependent Resistors) as voltage dividers. The wiring is similar to this: The problem I am facing is that the ...
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2answers
86 views

Working out current, voltage and resistance in a Bridge circuit?

This community is so helpful, my thanks go out to any comment I got with helpful advice. Here's another homework problem. I've tried working most of it out, but I have a feeling that I'll have to ...
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4answers
174 views

How would you solve this resistive network?

simulate this circuit – Schematic created using CircuitLab I'm not really sure how to solve this. I can't see any series or parallel connections. I need to find the Total resistance, V1 ...
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4answers
106 views

What is equivalent Resistor different Resistors put them in series or in parallel if they have a different wattage and different resistance?

What is equivalent Resistor of two this different Resistor put them in series or in parallel if they have a different wattage and different resistance? In practice somtimes we have a resistor with ...
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1answer
50 views

Controlling an electric water heater

I'm trying to control the temperature of water heated electrically. On devices sold commercially I see that temperature is not being controlled, and the heating elements are either turned on or off ...
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2answers
132 views

16 segment LED sparkfun resistor help

I am quite new to this and am struggling to read through the data sheets of the Sparkfun 16 segment display, datasheet here. I have managed to get all of the LEDs wired up through a LED driver, with ...
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2answers
91 views

The purpose of voltage-dividers in op-amp feedback?

simulate this circuit – Schematic created using CircuitLab So, here we have a typical op-amp with negative feedback. The non-inverting input is at virtual-ground, and if the input is ...
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1answer
44 views

What is variable resistors? [closed]

What is the role of variable resistors in the electric circuit? Please give an example of electric circuit for variable resistors.
-1
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1answer
101 views

Detect open or closed circuit via USB sensor

I have a relay which I need to detect the state of (similar to this question but no current flow) and would like know what the easiest method would be to detect the state via USB and Raspberry-pi. I ...
0
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2answers
86 views

Why is inductor completely canceling out current?

I used this calculator to determine that my hand-turned inductor has an inductance of approx. .5 uH. simulate this circuit – Schematic created using CircuitLab When I measure this ...
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3answers
153 views

Measuring the inductance of a coil?

I have a hand-wound coil I'm using in an LC Tank circuit. Using my multi-meter, I found out that the coil is drawing .6mA at 9v. Using Ohm's Law... $$R = V/I$$ $$R = 9/.0006$$ $$R = 15kΩ$$ Is there ...
0
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2answers
111 views

Voltage drop through a resistor using Ohm's Law?

I'm having a very hard time comprehending basic Ohm's Law. I was recently watching a video on the operation and use of Operational Amplifiers, and was completely lost because I couldn't understand ...
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4answers
81 views

Calculation of the input resistance of an op amp circuit

After I calculated that $$v_s=v_u\left(\frac{R_1}{R_1+R_2}\right)$$ I have to calculate the resistance seen by the voltage generator \$v_s\$. My book, without any calculation, says it is: ...
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3answers
254 views

Can I use a 5% tolerance resistor instead of a 10% tolerance resistor?

can I use a 5% tolerance resistor instead of a 10% tolerance resistor? It is for an organ from the 60's. All resistors stated in Schematics are 10% 1/2 watt. But I can't find a 6.8k 1/2watt 10% ...