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}\$)

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1answer
43 views

LED downlight current (amp) usage

I need advice on how to build a battery powered light setup in my house with what I have. Please be kind as I am a DIY newbie when it comes to off-the-grid solutions. Equipment: 1 x 12volt 36Amp ...
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34 views

I need help finding the power

I need help finding the power of the 1 ohm resistor in this circuit. Could you guys give any tips or even some clues to find it ? I've been trying for a while with Kirchhoff's circuit laws but ...
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how do we find the Norton equivalent circuit current of the both node ,a-b

Determine the Norton equivalent circuit current of the both node ,a-b, of 9 ohms resistors simulate this circuit – Schematic created using CircuitLab Solution: simulate this circuit \$V=RI=(...
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61 views

Why should we modify the voltage source value if the resistor is connected with it directly?

Why should we modify the voltage source value if the resistor is connected with it directly?i mean,there are two different circuit below ,and their corresponding equivalent circuit. As we can see,...
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1answer
35 views

How is voltage split between load resistor and C -> E on transistor?

I am confused by the voltage reading in this simulation as VCE reads as 907V which means almost the entire voltage is dropped over the VCE at the transistor. I assumed that the VCE should be a fixed ...
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4answers
88 views

Why can we see the current source as a open circuit and voltage source as a close circuit?

What is the \$R_L\$ value can maximize the power of \$R_L\$? simulate this circuit – Schematic created using CircuitLab The solution: simulate this circuit \$R_{th}=1+2+1=4\$,so when \$R_{L}=...
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51 views

How do we find where the average voltage resistor load formula came from?

Applying the half wave rectifier. We have in series a source called \$V_{in} \$, a diode and the resistor load. To find the average resistor load we use this formula : \$(V_{max} - 0.7) / \pi \$ I ...
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2answers
68 views

What resistor type is best for use as a heater?

I'm working on a design that requires I heat a bank of 18650 batteries during their operation. The plan is to mount the batteries along with large axial 2W resistors in to a PCB and using small ...
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32 views

Equivalent circuits in case of equipotential nodes

I have the following basic questions about circuit theory. 1) Consider a generic circuit. Suppose that, because of symmetry or other reasons, we conclude that two nodes A and B of it have the same ...
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2answers
41 views

How to get NTC resistor's temperature vs resistor curve?

I have a thermistor MF52203 whose rated resistance is 20k. However, the datasheet seems like not providing the temperature vs resistor curve. Without this curve, how can I get the corresponding ...
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1answer
31 views

How to calculate voltage of these nodes

How exactly does one calculate the voltage of the marked nodes and arrive at the numbers in the picture (1.75 and 1.628)? I fail when trying. :( simulate this circuit – Schematic created using ...
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7answers
11k views

Basic diode question about voltage-drop

We have been begun studying diodes in electronics 1 and I have really basic question that may be really dumb but I cannot find an answer online. If a diode is in series with a resistor and a voltage ...
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109 views

How to calculate Resistor needed in PNP Transistor Circuit

I am trying to calculate the resistor value I need to achieve 35mA in my circuit. Vcc is 5V. Can someone explain the values I need to find in the datasheet as well as formula to use to find the ...
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64 views

Finding value of resistor between two diodes

I'm using an Arduino and I have the following circuit: I couldn't find the symbol for analog signal, so the voltmeter represents a connection to the Arduino's analog input pin. How can I work out ...
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1answer
81 views

Small glass component with three colored stripes:yellow,green,and orange.The center of the component is a small cylinder

Small glass component with a tiny cylindrical structure inside the glass packaging.The colored stripes cover it up.
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47 views

Thermal Noise autocorrelation and time domain analysis

I have some doubts about the termal noise of a real resistor. The equivalent model of a noisy resistor is this one (here the reference): Here there is the model of a noisy resistive network: I ...
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1answer
43 views

Alternative to cartridge heater for 10mm deep hole?

I am designing my own version of a heater block for a 3D printer hot end. I had originally intended to use a 40W cartridge heater but the shortest length available I can find is 20mm and the geometry ...
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1answer
59 views

0603 LED resistor values

I have two LEDs The first one is directly attached to 3V3 and the other one is attacked to the SCK line on AT Mega 328P Here's the datasheet for the led (I am using the same LED) http://www.image....
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60 views

Identifying Value of Burnt 5-Band Resistor [duplicate]

I've been having trouble identifying the value of this resistor (see picture below) as the color codes in position does not make sense. It looks like a 5 band coded resistor. The 3rd band seems to be ...
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8answers
1k views

Why do I need 2 resistors to divide voltage?

I know someone else asked the same question, but I wasn't able to understand it. My question is, why do you need 2 resistors (1 to ground), to divide the voltage? Just 1 resistor would do the same ...
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1answer
71 views

Too High Ohm Load

I have a single 3.0 ohm sub-woofer and a 500W RMS amplifier. The speaker is designed to run as a pair or 1.5 ohm however I do not have the space. Is there any inexpensive solution?
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3answers
41 views

Convention to label components in a circuit

Given an un-labeled schematic like the below, is there a convention on how to label the various components? For example, would the 'top-left' resistor be R1? Would the one to the right of it be R2, ...
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1answer
98 views

Lowering resistance of potentiometer?

I saw a video where a person wired a resistor to the outer pins of a potentiometer to lower the resistance. Does this work? And if it does, can I still use the wiper and an outer pin with it lowered? ...
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solving circuit using mesh equations

Im trying to solve this circuit.I think ive got something wrong because the results are a little different than what i was expecting.Any help would be very much apreciated.Ive got this so far. -20 + ...
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2answers
75 views

Why do series resistors have a single current running through them?

In a circuit such as the following: The current is the same through all the resistors and is: ...
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4answers
100 views

How to model a load as combination of RLC (resistance, inductance capacitance?)

I have a constant voltage DC power source and a load connected accross it. The load consists of various sensors, modems, some small actuators, and something else which I don't know (mostly resistive.)...
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1answer
54 views

Can a USB power source run 4 IR LEDs in series without a resistor?

USB is 5V, and the voltage drop across the 5mm IR LEDs I'm gonna use is around 1.2V, if I connect 4 IR LEDs in series and perhaps more in parallel, do I still need a series resistor? Will cooling ...
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111 views

Resistor without terminals?

I have two terminals which I will measure resistivity between. I will be manually touching the terminal pair to different value resistors. The terminal pair might look something like a 9v battery ...
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1answer
140 views

Simple Transistor Resistor Amplifier Circuit Question

Can Someone Please Help Me On Solving this. I have tried and stuck..In a point that can I apply Kirchhoff's Voltage Law around R2,R4 loop. simulate this circuit – Schematic created using ...
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2answers
103 views

How to solve a LED-resistor parallel with a resistor?

Hi there I am curious as to how you would solve this circuit to know voltage drops and currents. It came about from a previous question I had asked which showed my understanding was not quite what I ...
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2answers
75 views

Confirmation on Diode in parallel with a Resistor

In a circuit with a resistor parallel to a diode/resistor, will the voltage across both resistors be the supply minus the 2v drop of the LED? Meaning you would calculate it still by using resistors ...
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1answer
272 views

What does the arrow going through the battery symbol represent?

I am currently studying Practical Electronics for Inventors, Fourth Edition, by Scherz and Monk. Chapter 2.5 Resistance, Resistivity, and Conductivity presents the following image (without description)...
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45 views

Controlled Temperature Coefficient of chip resistor

I am designing and experimenting with current source circuit using Op amp and transistor. As output current increases, the temperature rises which then makes the output current value to change for ...
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1answer
65 views

Resistor causing problems when in series with LED

I am wanting to dim the light on my computers power light, its just a 5mm LED what i am guessing gets 5v from the motherboard to power it The problem I am having is that when adding a 100R resistor ...
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1answer
29 views

Current going into the positive pole of a battery while discharging a capacitor

Please bear with me if this is a fundamental question. Let's suppose we have an RC circuit, charging a capacitor up to the voltage of a battery of 9V. The capacitor is currently at 9V, we switch the ...
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1answer
50 views

How to determine if installed braking resistor is correctly sized

I have a braking resistor attached to a system with a large rotational inertia. Everything works fine in terms of startup, rundown and normal operation. I would, however, like to investigate whether I ...
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46 views

Diffrence between cr0603 and r0603

I am shopping for parts on mouser and was wondering if someone knew the difference between cr0603 and r0603 concerning smd resistors. You see this one has code CR0603 https://www.mouser.ca/...
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48 views

Help regarding Ac current limiting using resistor

I've 12v(Vrms) 1A AC transformer. I need to regulate it to 1to 4ma maximum output without having much voltage drop. Output load is an animal skin which has resistance in it. Can I just use a ...
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2answers
96 views

Why is voltage drop independent of this 4 Ohm resistor?

I have this resistor which is connected to some battery (not very important). I don't understand why the total voltage is equal to the voltage drop over the 3 \$ \Omega \$ and 2 \$ \Omega \$ ...
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66 views

What is the total resistance in this circuit?

simulate this circuit – Schematic created using CircuitLab The parallel bit is easy enough but that 150k ohm keeps bending me over. If you could tell me how you got the answer it would help my ...
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1answer
65 views

JFET circuit solving

I want to find out the value of R2, R3, R4, R5. How can I solve it? anyone can help me? For JFET1 VGS=0v, VDS = 15v. For JFET2 VGS=1v, VDS = 18v.
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Why does LED dim when adding second LED in parallel with a single resistor

If I have a led hooked up to a 12v DC supply with a single resistor it runs nicely as you would expect. If I add a second LED in parallel the brightness drops, slightly, the brightness on both is (to ...
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1answer
33 views

Figure out the Resistance Value With Known Device Specs

I'm learning electronics and trying to find the right resistor value for my device: a Eachine Rotg01 Receiver. The specs ...
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2answers
114 views

LEDs in series without resistor

Say I have an ideal situation (good quality functioning power source and components) - 12V source and 3V (each) LEDs. Can I wire these 5 LEDs in series to the 12V source without a series resistor and ...
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2answers
35 views

Position of the voltage source with parallel resistors

In the following circuit I want to calculate the current flowing through the voltage source (node A) simulate this circuit – Schematic created using CircuitLab If I use the KCL I get \$I_A = ...
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2answers
94 views

Power resistor dealing with quick high current surge

I am currently working on a circuit to deal with the high inrush current of high value capacitors. I'm calling this a 'capacitor adder' as the rest of the circuit (output load) is already powered ...
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43 views

Why does a circuit with only reactive components have infinite Q factor?

So I came across the statement in my textbook. So I have been trying to understand why this is the case, however I just have not been able to understand
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1answer
41 views

Fairy lights dimming over time

I have had this cheap set of fairy lights for a few years. Powered by 3xAA batteries. Recently when they are turned on they start bright as they always were then proceed to get dimmer and dimmer ...
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2answers
74 views

How to design two circuits with Instrumentation Amplifier to produce the same output?

I want to measure the current in a 5V circuit. The current is between 50uA and 2.5mA. The current is from a NTC and it changes slowly (10Hz measurement is fast enough). Here is the typical ...
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2answers
156 views

Using resistors in a simple Led circuit

I'm using an 18650 (4.2v unknown mah) to power 14 leds (2v 20ma) in parallel with a 100ohm 1w resistor on each led. Everything has been running fine for 12 hours now with no problem. My understanding ...

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