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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3answers
52 views

How to measure the resistance of digital potentiometer AD5241 in circuit when power on

I have designed a transimpedance amplifier including a digital potentiometer AD5241. The circuit is showed below. I want to test the AD5241 to make sure it works as designed. simulate this ...
0
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0answers
21 views

Solar charger under rapidly varying conditions/impendance

My solar equipment consists of: Solar panel capable of: 20V Peak / 3.6A Peak Li-Ion Battery pack: 8.7V, 9Ah, (2S3P setup) My solar charger setup consists of: 5A DC-DC BUCK converter (XL4015) ...
4
votes
6answers
180 views

Given a known power supply, what are safe ranges for the volts/amps/ohms of connected components? [duplicate]

I'm new to hardware and am coming from a software background. I have an SoC that will be powered by a supply generating 5V and 1A. I'm trying to figure out what are the safe ranges of volts/amps/ohms ...
0
votes
6answers
269 views

Why are resistor values constant in the face of changing voltage and current?

Small question, I see that resistors are labeled in certain increments (e.g 5, 10 50 Ohms), although a resistor outside of a circuit is completely without voltage and therefore current. Does this just ...
0
votes
3answers
103 views

Why doesn't linear resistance scale proportionally with the square of length?

I have an in depth question about basic proportionality of resistance. Why doesn't it scale with the square of length? I ask this because what is causing the potential difference on two leads is ...
0
votes
0answers
51 views

Inducing Eddy current in wet clothes

Is it possible to induce eddy current in wet clothes and dry them using the resistance heat generated? I don't want to connect any wires to the clothes.
1
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1answer
84 views

Understanding a power source's internal resistance?

I have a mechanical system that requires a certain amount of electrical power. Now, when I calculated everything I did not include the internal resistance. For example: I calculated that the ...
0
votes
2answers
80 views

Why can I put a resistor at either lead of this LED and still see its effects? [duplicate]

Just to add a little bit of context to the question, I am using an Arduino Uno and a breadboard. I have a 5V power source running to the positive (longer) lead of an LED (rated at about 2v and 20mA). ...
0
votes
6answers
77 views

How do I figure out the exact voltage and current needed for a part?

Whenever I look for parts in my local electronics store, I come across parts(e.g a speaker), that have just a power rating stated(e.g 2W). While I know how to calculate power,voltage, resistance etc, ...
0
votes
1answer
52 views

Proper resistor for simple circuit

I have a potentially stupid question, but I have no idea how to handle the problem. I want to use 9V battery with a diode that requires 5V. So I need a resistor. How do I find the resistance if (as ...
0
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2answers
46 views

Finding load resistance to achieve max power transfer

1) So, to find Thenevin equivalent resistance, R-Th, I disconnect R_L and disable the voltage source by shorting it out. ...
-1
votes
3answers
76 views

Conductivity of plastic, wood and leakage current of laptops

Back around 2010, there were incidents where the surface of laptops have conducted 20-100V and have electrically shocked users. There is no doubt most of the newer laptops still conduct a continuous ...
2
votes
2answers
85 views

Using audio amplifier speaker output to drive an electromagnet

My first time here as a poster so forgive me if I make a misstep... I am building a coil (22swg enameled copper wire, about 500 ft), some 4in inner diameter of the bobbin, 1" wide, will have ~ 450 ...
1
vote
2answers
81 views

Use of inductors vs resistors

Why would we place an inductor in series with a lamp, rather than just a resistor? I'm sort of thinking it has something to do with being able to control voltage to the lamp, without effecting ...
0
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2answers
43 views

Non-parallel, non-sequential circuit

This is the circuit: I've simulated it and got a current of 30.76mA at the voltage source (5V). With this I've calculated the total resistance to be 162.5 Ohm. Each resistors is 100 Ohms big. But ...
0
votes
1answer
43 views

Two-port network: find fundamental parameters

What is the easiest method to find the ABCD parameters? I tried replacing the middle part of the circuit (R2,L,C) with an equivalent impedance and then finding U2 depending on U1, but it is very ...
0
votes
1answer
204 views

How to calculate the resistance of a complicated circuit?

I learned in high school the basic rules of how to compute resistance between two points, given a network of resistors. You try to rearrange the circuit so into parallel parts and series parts, then ...
5
votes
1answer
120 views

Kelvin “4 Wire” Resistance PCB Design Questions

I am designing a PCB that will utilize 4 wire measurement for 40 or so test points. A little background here - day to day I troubleshoot PCB's to component level, I'm an electronics technician and ...
4
votes
2answers
132 views

Resistance measurement voltage - multimeters

What voltage/current is applied by modern multimeters to determine resistance?
7
votes
3answers
576 views

Resistance, and learning for beginners

I am building an electrified "fence" of sorts to keep slugs out of my raised garden beds. The "fence" consists of two 18ga galvanized steel wires, stapled to wood and connected to a 9V battery. The ...
1
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3answers
115 views

Unbalanced pi- attenuator - Problem with simulation

I've been trying to simulate the asymmetric pi-attenuator example on this page with different source and load impedances: http://www.electronics-tutorials.ws/attenuators/pi-pad-attenuator.html I ...
12
votes
3answers
1k views

Will doubling thinner wire in lieu of thicker wire work?

I've been needing a jumper cable for a while and have plenty of 10 AWG copper wire lying around. From what I've read, 6 AWG wire is recommended for jumper cables. I want to make a 7 foot cable. So, ...
1
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3answers
121 views

Calculate voltage, current and resistance in a complex mixed circuit

How can I calculate voltage and current on each resistor (especially R5) in this circuit? What is its overall resistance? I have no idea how to do this.
1
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3answers
54 views

Controlling power?

From Ohm's law, we can control the voltage and current of a circuit by changing its resistance? Say we have a power source of 10kW, we can increase V by increasing R, and we can reduce V by reducing ...
0
votes
4answers
126 views

How can I minimize the variance in voltage drop across transistors - or eliminate transistors from this design?

I have a fairly simple circuit that I'm using with an arduino to measure the impedance on a very low-resistance circuit. The user plugs in a device at A and B and the arduino can compute the ...
6
votes
1answer
549 views

What does “OC” mean?

My Bluegiga WT-32 manual ("Stereo CODEC ADC characteristics" table) says: Allowed Load --> Resistive, min.:16(8)Ω , max.: OC What does OC mean in this case?
0
votes
0answers
55 views

Minimum AC voltage that causes nerve damage?

What is the minimum AC(50-60Hz) voltage that can do harm/nerve damage? I know that a few hundred volts (even 100?) has been documented to cause nerve damage that resembles a crush injury. I also know ...
0
votes
2answers
76 views

What is the strain gauge resistance variation of a 3-wire loadcell?

A 3-wire loadcell have two strain gages with a no load resistance of R. When a load is applied, the resistance of one strain gauge will change to R+dR and the other will change to R-dR (because one ...
2
votes
2answers
118 views

Why do you need a thicker wire when wire length increases?

Question: So far I've found that the thickness of the wire influences the resistance. A thicker wire has less resistance. Also, the length of a wire has a linear correlation with the resistance. 2x ...
-1
votes
2answers
71 views

If resistance is very high?

$$ V = IR $$ If there is a conductor with very low resistance, moving in a magnetic field, will it induce low EMF = IR? And a high current? Im confused at that point... Lets assume a conductor ...
0
votes
4answers
137 views

How does a potentiometer work?

A lot of places where I've read explanations about potentiometers either go into so much detail or they're so superficial that I don't understand the actual concept behind it. How would you easily ...
1
vote
1answer
65 views

Minimum electrical resistivity of contact material for human protection from lightning

The context of the question is camping and sleeping outdoors in the unprotected elements. If you’re sleeping in a tent close to the ground, and lightning directly strikes your tent or the vicinity ...
0
votes
1answer
39 views

Is the Delay in Strain Data Due to Capacitance?

I have designed a sensor board which gives a strain o/p based on wheatstone bridge principle(change in stress is measured through change in resistance). But the starting value is not at zero level,it ...
4
votes
6answers
1k views

Over 10,000 amps?

Is it possible to have a 5 meter wire that has 10,000 amps or more current flowing? I assume this can be done with a step-down transformer and the voltage could be 2V and lower... I assume that most ...
2
votes
3answers
222 views

Input resistance of a transistor circuit

I have a question from the razavi's microelectronics book: I'm puzzled because in the solution provided, the first line states that: "We know that the input resistance Rin = R1||R2||\$r_π\$." ...
3
votes
1answer
107 views

Use water as a conductor for a circuit powered by 1.5v battery

I've tried to create this quite simple circuit. V1: 1.5 v (AA battery) LAMP1: 1.5 v, 0.2 a (E10 incandescent light bulb) "Salt water": 10 ml regular water + 1 g salt When I connect the wires ...
-3
votes
1answer
63 views

Circuit design for variable number of leds [closed]

I am very new to this field and turned onto it by adruino and raspberry pi. So for my next project I am looking to create, I wanna have 6 leds (20mA 3v) in a line. Now depending on my output from ...
2
votes
2answers
54 views

Can I use a higher ohm resistance relay?

I'd like to build the circuit detailed here, which calls for a 12V DC 260Ω resistance relay: Looking at some relays, what consequence would using a 400Ω relay have? Would I be able to use one ...
1
vote
1answer
57 views

Impedance measurements of Nano-Materials using Hioki 3532-50 LCR HiTESTER [closed]

I have been using Hioki 3532-50 LCR HiTESTER (manual) to measure the impedance, Parallel capacitance and phase angel of nano-materials at different temperatures from ambient to 1150 °C. Lately I have ...
5
votes
6answers
881 views

What is the function of the resistor in the below circuit?

What is the function of the resistor R13 in this circuit?
0
votes
2answers
97 views

At what resistance do I not see a voltage drop across a resistor?

If I have a circuit like this and measure the voltage drop across the resistor I get a value, regardless of what resistor I use: However, if I stick a piece of wood in there instead of the resistor ...
0
votes
3answers
92 views

Why are the Resistance/Resistivity Equations Formulated as they are?

The equation for temperature dependence on resistivity: $$ \rho(dT) = \rho(0)(1+\alpha dT) $$ where \$dT\$ is change in temperature from some reference and \$rho\$ is resistivity. This leads to ...
1
vote
1answer
47 views

Interfacing GPIO pins between a uC and RS-485 tranceiver

uC: EM357 datasheet RS-485 IC: sp3078e datasheet Two input pins on the sp3078e need to go high at the same time when I'm sending bytes. I'm using a single output pin on the EM357 to drive both of ...
0
votes
3answers
95 views

Resistance calculation [duplicate]

Are these resistors in parallel? A question is asked to find the equivalent resistance between X1 and X2; to my knowledge, these resistors are like parallel connections. But the choices are given ...
1
vote
2answers
131 views

Find total resistance of this circuit

I want to find the total resistance between A and B. This is a HOTS mcq, which has the following options: A: 45\$\Omega\$ B: 15\$\Omega\$ C: 5\$\Omega\$ D: 22.5\$\Omega\$ A book says that the ...
0
votes
2answers
115 views

Can I use a diode to block current?

I am building a circuit from a 4.2 volt battery and I cannot use resistors to lower the current, and I cannot calculate the load resistance but I want to protect the switch from over current, and ...
-1
votes
1answer
104 views

How to choose the right transistor for a circuit and its associated resistor? [closed]

Please bear with me. It's easier asking you guys opinion than to Google. Especially choosing the right resistor when working with Arduino boards and transistors for relays.
2
votes
5answers
2k views

Is Ohm's Law violating itself?

Consider the following circuit... simulate this circuit – Schematic created using CircuitLab Now suppose the resistor has infinite resistance. Then obviously the current through the ...
2
votes
2answers
102 views

Reducing voltage for solid state relay

I have a solid state relay which wants a 1.25-2.5V "activation" input, but my output from the micro controller is 5V. Is it possible to use a zener diode for this? Or do I need a buck converter? I ...
4
votes
7answers
264 views

Resistance of a semiconductor diode

When we calculate the dynamic resistance \$r=(\frac{dv}{dI})\$, for any n-p junction, how is it different from the normal resistance \$R=\frac VI\$? Does the equation for the voltage drop (The fermi ...