Questions tagged [resistors]

A resistor obeys Ohm's law (\$\small V=I\cdot R\$); the current through it is equal to the voltage across it divided by the resistance (equivalently \$I=\frac{V}{R}\$).

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Calculating Currents and Power in a Circuit with Multiple Resistors and a Voltage Source

I'm currently working on a project that involves a circuit with a single voltage source and multiple resistors, and I've hit a snag with my calculations. I could use some guidance from anyone who's ...
bittscoterie's user avatar
1 vote
1 answer
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How supply an outdoor string light with 10 LED bulbs 0.8W?

I currently have a outdoor string light with 10 LED bulbs 0.8W powered by a 3.7V lithium battery and recharged by a solar panel (5.5V 295mA). Over time the battery discharges and no longer works. I've ...
Thom's user avatar
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Power Electronics Exercise [closed]

Can someone help me solve the following exercise? In English, parts a) and b) ask: a) What is the value of "R" when we have a value of 10A as the effective current? b) What is the average ...
William's user avatar
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1 answer
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How to calculate total resistance and identify which resistors are in series?

How to calculate the total resistance and identify which resistors are in series? I'm really lost with this one. How do I properly read this?
MikeD's user avatar
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4 answers
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How to calculate LED voltage and current based on resistor value and source voltage?

I'm talking about a simple circuit - source, resistor and LED in series. I've seen many examples of how to calculate the resistor value based on source voltage and the desired current and voltage of ...
Catalin Florea's user avatar
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CJMCU-3652 resistor dimensioning

I bought a CJMCU-3652. It is based upon the LT3652 from Linear Technologies. In the datasheet on page 15 there is a description on how to calculate the resistors to properly charge whatever battery ...
Cowboy_Patrick's user avatar
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0 answers
32 views

help identifying [closed]

I'm trying to identify & replace this resistor. Its out of a skar 2000.1 amplifier.
Tony Grantham's user avatar
2 votes
2 answers
496 views

What is meant by operation mode of a resistor?

The datasheet refers to different operating modes for the resistor with the below note- What does it really mean? Note: The presented operation modes do not refer to different types of resistors, but ...
Divya K.S's user avatar
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5 votes
6 answers
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How can current phase shift be 90 degrees behind voltage just "inside the capacitor" on an RC series circuit but be in phase in the resistor?

Imagine an AC source in series with an RC circuit. In this video, the instructor claims current will be 90 degrees behind voltage inside the capacitor but not inside the resistor or the whole circuit. ...
Duck's user avatar
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Rheostat with parallel resistor, how to make the taper more linear?

I'm using a 10k potentiometer wired as a rheostat in parallel with a 470 ohm resistor, because I need a (roughly) 500 ohm variable resistance in a circuit. The type of potentiometer I'm using is not ...
one_three_three_seven's user avatar
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2 answers
126 views

Why are the two resistors in parallel? They are next to each other, so they should be in series, right? [closed]

Why are the two resistors in parallel? They are next to each other, so they should be in series, right?
LucyRoseM's user avatar
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How to lengthen the short pulse of a turn signal?

I am trying to upgrade my motorcycle with LED turn signals. The issue is with the particular light I am using and I believe I can solve it with a simple circuit addition. Please excuse any incorrect ...
VashTheStampede's user avatar
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2 answers
60 views

Understanding how to read current direction when it is opposite to voltage direction [closed]

I need to completely understand how to find the value of each resistor in this circuit. I understand that with R1: i1 and V1 flow in the same direction and Ohm's Law can be directly applied but could ...
9_daytona's user avatar
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2 answers
78 views

Ammeter Shunt Change

I’m attempting to retrofit an external shunt style ammeter into the charge circuit in my car but am far from an electrical engineer, so I figured this would be the best place to ask. The ammeter I’m ...
Charger512's user avatar
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2 answers
64 views

Are measurements of battery voltage enough to test its state of health?

What I mean is that I might have 3.5 battery voltage, and I rarely use it. Note: If I measure the voltage it shows 3.5, but is not the internal resistance changed decreasing the current? If that is ...
Ali's user avatar
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What is the equivalent resistance between A and B?

I was solving this problem: As it appears, this is a collection of resistors put on the sides of trapezoidal pyramid. I have solved this problem and my answer is \$ \frac{12R}{35}\Omega\$, but the ...
Jack's user avatar
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3 answers
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LED and resistor in series on 24 V: resistor power rating

Can I connect a 1/10W 0603 resistor (4 kΩ) and a 0603 LED (I = 5 mA) to a 24 VDC supply? Will the resistor burn out in this connection?
SY Mak's user avatar
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1 answer
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Victron Charge Controller with Amperage limit

I'm looking into charge controllers that have features to limit the charge rate of a battery. I've got a small battery bank, and only want to charge at say 10Amps max. It looks like many of the ...
2b77bee6-5445-4c77-b1eb-4df3e5's user avatar
0 votes
2 answers
95 views

Voltage and resistors

I put a 100R resistor to the output pin of a Raspberry Pi Pico and the amps went down from around 50mA to 15mA, but when I check voltage it stays the same at 3.3V. Am I doing something wrong when ...
My SK's user avatar
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-2 votes
0 answers
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Diode / resistor networks and output voltage

[![enter image description here][1]][1] ** ALL THE VOLTAGES AT THE BOTTOM THAT ARE CUT OFF ARE -3 V** Using piece-wise model for diode I am using the equation Vd = Vdo + Rd*id and Ohm's law to find Vd ...
user364328's user avatar
8 votes
4 answers
945 views

Impedance matching and termination resistor

I’m a little confused regarding impedance matching with resistors. As far as I know, the impedance of a trace is a part of its characteristics and it can’t be measured with an ohmmeter. For example, ...
mehrad aghaei's user avatar
1 vote
1 answer
72 views

HOW TO FIGURE RESISTOR WATTAGE

I am trying to understand how to figure a resistors wattage based on label.
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2 votes
3 answers
113 views

Art project using SMD LEDs and resistors

I am trying to light a sculpture from the inside with an SMD LED and resistor due to space limitations. I am ready to do some tiny soldering, but can't find the right resistor. The calculator tells me ...
Jerny's user avatar
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1 vote
1 answer
119 views

Are large scale wire wound resistors used?

I have many different large wire wound resistors. Are they still in use? It is 71.0 Ohms, tests at 72.3. Are they obsolete?
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2 votes
2 answers
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Circuit that turns on an LED and turns it off after some time

I want to create a circuit that turns on an LED when a switch is flipped and automatically turns it off after some time. I use a capacitor for the timedelay. Because I want it to be able to be reused ...
Ron Beton's user avatar
-1 votes
2 answers
62 views

Why does the resistor need to be placed before the junction in an RTL NOT Circuit

I am trying to implement a simple inverter using transistors. I am confused why placing the resistor between the junction and the LED will not work, but placing the resistor before the junction does ...
michael_fortunato's user avatar
3 votes
2 answers
192 views

Is this a non inductive resistor? (bands won't match usual tables)

Can someone tell me how to read this resistor value? After reading When your 5 Band Resistor is not a 5 Band Resistor on the DigiKey forum I realized this is a 4-band resistor, and the 5th band is ...
tfm's user avatar
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1 answer
79 views

Resistors in audio circuit [closed]

I have a question regarding an audio circuit that I have. This is the general/simplified schematic: Pretty much what is happening in this circuit is the black is what was previously on the circuit. ...
Syd's user avatar
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0 answers
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Can anyone identify this power resistor?

I'm trying to identify this power resistor.
Mikey's user avatar
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2 votes
1 answer
71 views

What size should I select for the resistor? I have led and SSR and 24VDC source [closed]

Could you please clarify this circuit with me? I have selected 90 ohms. Please let me know if I need to do something differently here. R=(24-30.3)/20mA= 1035ohm and I select 1Kohm I appreciate any ...
AAS's user avatar
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1 answer
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How to determine maximum supply voltage of a circuit

I am working on a small electronic device. I am trying to find the maximum supply voltage I can inject into the circuit before damaging one or multiple components. The circuit (in CEI) is the ...
Munshine's user avatar
2 votes
2 answers
87 views

How big a pull-up resistor is needed to pull up an internally pulled-down GPIO (ESP32-C6)?

I'm feeding a BCD diode matrix of switches with Vcc at 3.3 V and running the BCD outputs into GPIOs on the ESP32-C6. The plan is to set each GPIO input to internal pull-down so I can pull it up ...
KJ7LNW's user avatar
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0 votes
2 answers
62 views

Designing a current sensing op-amp circuit for an AC load

I'm trying to simulate a current sensing op-amp circuit. My AC voltage, 24 VAC, is across a load of 10 Ω. I used a 100 μΩ resistor and measured the voltage across it using an op-amp. Looking at some ...
Bilal's user avatar
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0 votes
2 answers
135 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 ...
SkePsis's user avatar
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12 votes
8 answers
6k views

What are 5 gigaohm resistors used for?

I have a resistor which is 5 gigaohm according to its color bands, but when I measure it, it shows me 1 ohm. I tried to find 5 gigaohm resistors online but couldn’t find anything. Does it really exist?...
wolyure's user avatar
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0 votes
2 answers
90 views

What is it about LEDs and resistors that makes it so order doesn't matter? [duplicate]

For reference: I was trying to figure out why I can put a resistor before or after an LED for it to work. I found an answer here that says: The LED only sees the difference in voltage between its two ...
JVDS1069's user avatar
1 vote
0 answers
85 views

Stuck in a Thévenin's Theorem exercise

I'm practicing applying Thévenin's Theorem, and I'm struggling with computing \$R_{th}\$ in the following circuit: My attempt: after removing voltage and current sources, and combining resistors in ...
Sam's user avatar
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15 votes
20 answers
3k views

Reasons to use combinations of resistors (parallel or in series): Looking for educational examples

I teach physics at high school level, and one of the topics I cover involves instructing students on how to calculate the total resistance of two resistors, whether in parallel, in series or simple ...
Julia's user avatar
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0 answers
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Two reasonings reach the same solution, yet one must be wrong [duplicate]

Another follow-up to this post, regarding this circuit: Above \$V_1\$ applies a rectangular wave of amplitude \$24\ \mathrm{V}\$. For this post I'm only concerned in the case \$V_1 = -24\ \mathrm{V}\$...
Sam's user avatar
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0 votes
2 answers
162 views

Why is the right half of the circuit irrelevant?

A follow-up this post regarding the following circtuit: I continue to struggle to understand why the right half of the circuit is irrelevant when computing the voltage between \$A\$ and \$B\$. One ...
Sam's user avatar
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1 vote
1 answer
81 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 ...
Wer Bn's user avatar
  • 111
1 vote
1 answer
85 views

Identify resistor on Daewoo AVS1339 speaker

I have a Daewoo AVS1339 200 W barrel speaker. It failed the other day and no power is getting to the display. After some testing with a multimeter and visual inspection I found a resistor with scorch ...
Jason's user avatar
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1 vote
2 answers
88 views

How to choose the proper value of resistors for current dividers

Edit: The original version of this question is malformed. There is an edit further down below with an updated explanation of the issue I'm trying to solve. In a simple current divider, I know the ...
Ciro García's user avatar
0 votes
2 answers
140 views

Multimeter won't read resistance

I have an issue with my digital multimeter (Flir DM66). It won't read resistance. I've tried reading dc voltage and continuity, both work fine. But when I try resistance, it shows 0.8 when touching ...
Lovely Noises's user avatar
1 vote
0 answers
45 views

SIMPLIS VPWL & IPWL resistor

I am trying to define RDS(on) to simulate the MOSFET to be used in one of the converter topologies in SIMPLIS. There are two different types of resistor in SIMPLIS defined as below: VPWL: The ...
Mhan's user avatar
  • 105
1 vote
5 answers
173 views

Min and max resistance of this network with potentiometer

As the 20 kΩ pot is adjusted from A to B, any idea what the minimum and maximum Thévenin resistance is between C and D? Any thoughts on some equations?
steveK's user avatar
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0 votes
2 answers
137 views

How to extract voltage and current from this real-life circuit (with resistors)

I recently measured some voltages across two resistors as you can see in the images below. I used a triangle wave as voltage source and measured the voltages across the resistors with an oscilloscope. ...
Leon's user avatar
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0 votes
1 answer
61 views

Resistor test mode in ICT

My ICT machine has 2 resistance measurement modes on the PCB: Mode 1: Constant current mode for each resistance value (Figure 1). In this mode, we apply the formula V = I * R to calculate R. Mode 2: ...
Hoài Nam Nguyễn's user avatar
4 votes
3 answers
305 views

Why is resistor used in RC circuit?

Why is the resistor used in RC circuit? Is resistor used to oppose the current flow in RC circuit?
Geetha Akshaya's user avatar
2 votes
3 answers
893 views

What resistors for a 4 LED Arduino/breadboard project?

I am currently working on a school project for my work-study. The project is super simple: light up 4 LEDs, in various patterns, using a push button to cycle through the modes. I'm using 4 colored ...
Dio B.'s user avatar
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