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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42 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 ...
-4
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4answers
90 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
21 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 ...
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1answer
63 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
182 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
59 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
24 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
89 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
72 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
43 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
454 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
27 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
52 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
50 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
53 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
52 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
59 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
77 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 ...
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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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4answers
308 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
64 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 ...
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2answers
45 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
79 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
163 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
77 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
47 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
126 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
79 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 ...
-2
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1answer
43 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.
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1answer
82 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
84 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
126 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 ...
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2answers
101 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
78 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
239 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% ...
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2answers
71 views

wire gauge for solderless lithium batteries in series?

I am making a prototype lithium battery of 2kw / 40 amps. it's 8p14s, and every bank of 8 parallel is joined with copper sheet in solderless contacts. I have bought some 0.1mm thick copper sheet and ...
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3answers
66 views

Is it reasonable for a potentiometer to have a minimum of 1.3Ω?

I purchased a 25Ω linear potentiometer, and found that the minimum resistance is 1.3Ω 0.9Ω. I expected that the minimum would be closer to 0Ω. Is this typical? Should I return the potentiometer as ...
0
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0answers
46 views

How can I add a resistor in parallel to a rheostat while keeping it linear?

I have a 25Ω linear potentiometer wired as a rheostat. I would like a range closer to 5Ω, so I added two 10Ω resistors in parallel. This gives me a range of 0 to 4.16Ω which is just fine, but the ...
1
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3answers
1k views

Powering a device by USB?

I would like to power a device via the 5V USB port on a computer, because I will also be communicating with the computer via the USB data cables. I know that USB ports provide 5V, but from what I've ...
2
votes
1answer
76 views

Maximum Amperage AA Battery

I have a simple question. How many amperes can an AA battery draw? I'm studying electronics and looking at the Ohms law: V=IR and taking as an example a 1.5V AA alkaline battery, and considering the ...
0
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2answers
115 views

Is there a way to measure three discrete resistances simultaneously?

I'm working on a test box for fencing body cords. These cords are always 3 wires, and will plug into a box that I'm still designing. The test box I currently use connects to a multimeter and has a ...
0
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1answer
54 views

Filtering noise off of PWM signal

I am trying to measure the resistance of a nichrome wire that has a PWM (1000Hz and different duty cycles between 0 and 100%) voltage applied to it from a 5.0V regulator. The setup I have in mind ...
0
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2answers
52 views

e12-table - replace resistors

Is this the table of 12 resistor series? 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 http://sv.wikipedia.org/wiki/E12_%28resistorserie%29 And if I have a resistor of let say 1670 ohm - how do I ...
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2answers
147 views

Trouble converting 12VDC incandescent to LED: lack of resistance

I'm converting two, independent, incandescent bulbs (OEM 212-2) fixtures to use LEDs for automotive map reading. Each incandescent bulb (12-volt/system) measures 1.5 ohms with a meter; however, there ...
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1answer
68 views

Is there a way to find this resistance? [duplicate]

I have done thevenin analysis on a larger circuit and have gotten the result below. I need to find the value of RL. Would I use thevenin again? But that would give me the same result because I would ...
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2answers
79 views

Grounding a wire using a chunk of metal?

So I've made a complex LED grid and it works but has ghosting in some of the rows. I've given up trying to work out the reason why, but have noticed that when I touch the SCLK wire, or connect the ...
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1answer
71 views

Voltage used up by a transistor and shift registers

i am on a project 8x8x8 LED cube and I am stuck on the value of register i should use. Talking about single layer I am using 2N5296 transistor for common cathode and 8 shift registers for controlling ...
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0answers
40 views

fuse metal alloy with high springiness?

Is there a fuse alloy that would have the same springiness as this except with a little wire that comes out and that plugs into something, so that it could be machined and pressed from one single ...