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Questions tagged [resistors]

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

-2
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0answers
21 views

Chromebook power circuit: Surface mounted diode or resistor? [on hold]

I recently enjoyed finding out a mains power short (was working onsite project) has dislodged 2 surface mounted components from my device's motherboard. Thought it would be interesting to repair ( ...
-1
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0answers
38 views

Resistance and voltage [on hold]

Will this circuit need the resistance? Similarly what will be the prescribed voltage, resistance for these 3 leds of 3 watts.
0
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1answer
31 views

How to find the output voltage of a system with a computing amplifier?

I got a question regarding the following system. The only given value is the input voltage $$U_e = 8V.$$ Now the task is to find the output voltage $$U_a.$$ My question now is how do I find this ...
0
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1answer
27 views

What is the purpose of higher-resistance resistors in Astable Multivibrator circuit?

The astable multivibrator circuit has two higher-resistance resistors (47k on the pic). What are they there for? Wouldn't it work without? And what is exactly their function? I spent a lot of time ...
0
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3answers
133 views

Make an LED (20 LEDs) circuit battery efficient

I want to wire up a miniature wargaming figurine to have 20 LEDs. As I've poked around options my concern is the battery life and how often the battery would need to be replaced. Since each gaming ...
0
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3answers
80 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 ...
2
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1answer
120 views

Why is my led not on?

Hello I’m just a beginner and I made a simple circuit with a resistor and a capacitor with a led in between. As I understand the capacitor just accumulates the energy but why is my led not going on? ...
0
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1answer
29 views

Relay or SSR for electrical heating from tado smart thermostat?

I have a Tado smart thermostat system to switch my electrical underfloor heating. It offers a simple NO or NC switch. This is rated at up to 6A. (Aside: Tado is not a good company. They provide no ...
0
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1answer
41 views

Controllable power source (current) with one transistor and one resistor

I have this circuit: It should be a controllable powers source for current. Is that right? 1) What's the name of this circuit? 2) What does the resistor and how can I calculate it? Thank you!
0
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3answers
25 views

Making a parallel connection = increasing the total current?

Considering the scheme below simulate this circuit – Schematic created using CircuitLab Am, I understand correct, in real life, if I will step-by-step add the parallel resistors, the total ...
0
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1answer
46 views

Determine resistor's value

Can you help me identify this resistor please? Is it 1.91 ohms resistor? In such case where would I find such resistor to replace this burned one?
0
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1answer
45 views

What does “resistor as a reference” means?

I have a book with some projects examples that use Arduino, one of the projects use piezo to detect vibrations. The book says the following: When plugged into 5V, the sensor (piezo) can detect ...
4
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3answers
679 views

How do I figure which LED I need?

I need to replace two LED diodes on a TP4056 board (bottom right corner on the picture). The board is going to be in a box and I want to move diodes to the small holes in the box. There are two ...
0
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1answer
40 views

Calculating SMD resistor temperature rise

I am interested in knowing the actual power dissipation of an SMD resistor at a 70C ambient temperature. I am looking at a 10kOhm 2512 1Watt resitor RMCF2512JT10K0. from the electrical specifications ...
0
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3answers
87 views

Voltage in RC circuit with unknown frequency

We were given the task of finding the voltage drop across R1 of the circuit below with the following alternatives: 5.8V 4.8V 4.0V 10.0V All given information is contained within the image, i.e. no ...
1
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1answer
103 views

Why Current draw in DC variable power supply is not sizable?

I have done a DC variable power supply, and checked it using multimeter the output voltage ranges from 1.3v to 19v, but the problem is when I added a DC load(small DC motor) it was not working, why? ...
0
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0answers
44 views

Find voltage across load resistor

Here the zener voltage of the zener diode is 3.3V and base to emitter voltage drop is 0.7V. What is the voltage across the load resistor and how to find it?
0
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3answers
51 views

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 ...
1
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3answers
116 views

Do the resistors affect every component of the circuit?

I've noticed something strange in the circuits schemes I saw in a book. Let's say that there is an LED and it's anode is connected to a 5V power source, and it's cathode is connected to ground. ...
0
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4answers
62 views

about formula in temperature of resistor

I have 10 watt resistor. I am using resistor with ac current. I need mathematical formula for learning temperature of resistor in t time. temperature of resistor depends P=V^2/R and time. Such as ...
0
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1answer
117 views

Why is there no resistor in a christmas LED string light?

I bought a bunch of different LED string lights for Haloween and Christmas. All of them are arranged as 2 sets in parallel. They are either 50 or 100 LEDs. I noticed that most of them have a molded ...
0
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1answer
61 views

How can I find the short circuit current across a and b?

In order to find R thevenin, I need to find Isc across a and b since there's a dependent source. Based on my calculations, Vth=500/3V. I've spent countless hours thinking about Isc,please help.
0
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0answers
26 views

What is the effect of the signals in output terminal?

I'm using superposition to solve this problem. I already know that for U1 the output is Ua1=-R/R. Unfortunately I'm not sure what is the output for U2 and U3.
0
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1answer
36 views

Voltage in a Y-Δ transform

I'm looking for a way to solve the following circuit Without the voltage sources on the circuit, I would be using a simple Y-Δ transform. But I'm not sure how I should proceed with them on. Which ...
0
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1answer
43 views

Realizing 2 Resistors are in series in an RC circuit

I understand that when the switch is open, the capacitor acts like an open circuit & therefore the current in the capacitor branch would be equal to 0. When I solved the circuit using nodal ...
0
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2answers
108 views

Why do we need a chain of resistors to increase the voltage? [closed]

I did a workshop on SMT today and we made this board attached. However, what I don’t understand completely is the logic: why do we need 3 resistors to increase the voltage (on the boost part)? What do ...
0
votes
1answer
117 views

Why does my LM393N (dual comparator) ignore its inputs completely when used with an LED?

I have made the following circuit: Viusalisation (not working): https://i.stack.imgur.com/tDA85.png Circuit (working): simulate this circuit – Schematic created using CircuitLab Left to ...
0
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0answers
45 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 ...
1
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1answer
40 views

Accuracy of the some components' values

I have some questions about the accuracy of some electric components, especially for SMD components. We can reveal that each SMD resistor has 1% or 5% or 0.5% of accuracy. I wonder if the accuracy ...
0
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0answers
43 views

RLC circuit with intial conditions

The circuit I have is given by the following schematic: simulate this circuit – Schematic created using CircuitLab I know a few things: The current in the circuit at \$t=0\$ equals \$\text{I}...
1
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3answers
120 views

What is this connection of resistors? Parallel or serial?

How i can simplify this electric circuit?
1
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1answer
51 views

led chaser with non-mechanical shut-off option

I've seen thousands of standard led chaser circuits online but I haven't seen one in which I can shut off all LED's in a non-mechanical way. I'm wiring one pin of my chaser up to a microcontroller so ...
0
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0answers
36 views

What kind of resistor could I replace a 0.18 ohm 3 pin cement resistor?

I have an audio amplifier that I would like to replace a cement resistor that has gone bad that is supposed to be 0.18 ohm 5W with 3 pins. Could I use a 0.22 ohm resistor as an alternative or will ...
0
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0answers
30 views

LED current rating

I have an unknown LED, I think it was previously run off of ~14vDC. I want to repower it - I have a 5vDC 3A power supply. I dont know the LED rating so I've rigged it up to a simple series circuit. ...
0
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2answers
72 views

Choosing a resistor for connecting a bipolar transistor

I need to run some LEDs using Arduino. The total current consumption is about 190 mA. For these purposes, I found a bipolar transistor PMBT2369 (Nexperia). Transistor characteristics: - Maximum ...
6
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2answers
650 views

LED- Resistor, does the position matter? [duplicate]

I was reading the MAKE AVR programming. One of the chapters suggests to solder resistor to the cathode side of an LED. But in our uni labs it's said to connect the resistor "before" the LED; that is ...
0
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0answers
28 views

RLC series circuit with initial current

I'm trying to solve, for the voltage across the capacitor in the following circuit: simulate this circuit – Schematic created using CircuitLab The initial current in this circuit is equal to \$...
0
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1answer
71 views

Why not use the same size resistors for each stage in a Kevin-Varley divider?

I was thinking of building myself a Kevin-Varley divider as described for example in this article about a mini metrology lab in the March 1996 issue of Electronis Now by Conrad R. Hoffman. The normal ...
0
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4answers
98 views

Safe Led resistor path [closed]

I know that Leds in parallel with one resistor is bad. I was wondering if this is still considered bad to do since all power is run through 1 resistor then split and run through other resistors ...
0
votes
1answer
58 views

Tactile touch button design using pull up resistor

As you can see on my github https://github.com/mancio/Volante-The-Gamepad I'm designing a gamepad with analog axes and digital touch buttons using pull-up resistors My pull-up resistor switch works ...
0
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0answers
40 views

What is the difference between voltage across battery and voltage across a resistor?

simulate this circuit – Schematic created using CircuitLab I am doing an experiment for a lab and I am confused as to what they are asking. They ask to measure the voltage across the battery, ...
0
votes
1answer
32 views

RC Integrator mean value

i am trying to understand the behaviour of an RC integrator for \$f>>1/RC\$, i.e. in the integration domain. I know that at the capacitor i have \$V = \int V_{in}/RC dt\$; experimentally i find ...
0
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0answers
50 views

Calculating value of a current limiting resistor in a constant current circuit?

I am using 12 leds in series with 3.0-3.4 v forward voltage and 400-500mA forward current (these values are from the datasheet). I am using a constant current led driver(24-40v and 580mA). My problem ...
1
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0answers
31 views

Source voltage of circuit with diodes when output voltage is given

Tried solving this using KVL, and solving to get the currents for the different parts of the circuit, however got stuck when trying to compute the source voltage especially that I'm unsure if the ...
0
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2answers
63 views

How to find the current in this circuit?

Please help me find the current flow in A1,A2 and A3. its my First FEE class and I was able to solve this with voltage source but with current source Iam Having trouble. also V1 and V3 are the ...
0
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0answers
45 views

How to Find Resistor for Maximum Power Transfer?

I honestly have no idea what is the best way to find RL for maximum power transfer in this circuit. What I do know, first and foremost, is that the RL resistor can be found as the Thevenin-...
0
votes
1answer
64 views

What resistor do I need?

I have an LED that is rated for 34V at 3A and about 100 watts. I am trying to figure out what power resistor I need with a 36V battery supply. I think I need a 10W 1 Ohm resistor but I am not sure. ...
1
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1answer
73 views

Calculating total resistance between two points (triangle resistor network)

I want to calculate the total resistance between the 2 points: A, B. I've tried using the Delta-Wye method, but I'm not sure how to apply it to my problem since there's 6 resistors and not 3 (usually ...
0
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2answers
33 views

The Relationship of Power and Heat to Length of a Folded Resistor

This question is a follow-up to a previous question of mine (The Relationship of Power and Heat to Length of a Resistor). We make heaters in our lab. They are 1.5 inches long and are made using 0.005-...
0
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2answers
65 views

What is the purpose of the resistor between the Vcc and discharge pins in the astable 555 timer?

In a standard astable configuration of the 555 timer, we have two resistors R1 and R2. The capacitor charges through both resistors but only discharges through R2, consequently, the high interval is ...