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}\$).
4,585 questions
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Confused with calculating Kirchoff Voltage Law [closed]
I'm a beginner student and am having some trouble understanding Kirchoff's Voltage Law and how to use it to calculate voltages across components. I'm stuck on the question shown in this post, and have ...
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Finding the current between two branches of resistors
The task is to find the current between P and Q if there was a wire connecting them. In another similar question there's just an ammeter between them and you're supposed to find how much current it ...
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What is meaning of forms in "they are even used as coil forms for inductors?"
From the resistor introduction in The Art of Electronics third edition:
Resistors are truly ubiquitous. There are almost as many
types as there are applications. Resistors are used in amplifiers
as ...
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What Victoreen is in "Victoreen high-resistance types"?
Figure 1.2. A selection of common resistor types. Top row, left to right (wirewound ceramic power resistors): 20W vitreous enamel with
leads, 20W with mounting studs, 30W vitreous enamel, 5W and 20W ...
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Do I need resistors in my circuit?
A little backstory. This is my first time creating a PCB with SMD high power LEDs. Or rather, first time to create anything on a PCB. One of my old LED Lights used for reef aquariums was not working ...
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Calculation of amplifying stages on bipolar transistors
please help me. i don`t understand how to do it
To develop a circuit diagram of an AC amplifier on a bipolar
transistor and calculate the values of the nominal elements of the developed
transistor ...
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Resistor purpose in following circuit
I would like to understand Why is there a small 20 ohm resistor next to the transformer? What is its purpose?
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Finding capacitor voltage in this seemingly simple rectifier circuit
I've been experimenting with a simple rectifier circuit and wanted to share some observations. Without R1, the circuit functions as the well-known half-wave rectifier, where the capacitor quickly ...
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Converting ATX PSU to bench power supply
I'm posting this question just out of curiosity and also I know that you guys are expert in this electrical stuff building projects. I used to watch electrical circuits building videos in youtube in ...
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Standard SMD chip resistor with higher power in the same package
I'm used to choosing SMD resistance package size according to the power they will need to dissipate (+ a margin). i.e: 0603: 0.1W, 0805: 0.125W, 1206: 0.25W, 1210: 0.5W, like you can find here.
But ...
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Thévenin's theorem exercise with two voltage sources
I have the following exercise:
I need to use thevenin's theorem to get the equivalent voltage source and resistor
I have redrawn it in LTSpice for better understanding:
I knew how to get the ...
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Polarize and monitor a large resistor like device
goal
My goal is to design a board monitoring the resistance of a device which is basically a resistor (5-500 MΩ) in parallel with a capacitor (10-100 pF).
The device must be polarized (ie. the board I'...
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Metal Strip current sense Resistor layout
I am using a current sense resistor in my design. I have a question regarding which end of the resistor to be used for connecting to sense amplifier. The footprint and the connection diagram is given ...
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Which RS485 topology is this and will this work?
I have a basic awareness of RS485 protocol but this is the first time I am working with so many devices on the bus which requires a specific placement so here it goes.
Will the following connection ...
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Inference of analog neural network in LTspice
I am attempting to replicate the XOR model described in the paper "Training End-to-End Analog Neural Networks with Equilibrium Propagation" using LTspice. Specifically, I am using the ...
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Best way to design a PCB for frequent component switching?
I'm getting a PCB made with an OpAmp circuit on it that will need some tuning. We aren't sure what resistance and capacitance values we'll need to use for the integrator circuit. These will need to be ...
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How to choose a relay? [closed]
I'm having trouble sourcing a 12V 20/30A SPDT relay (or similar) with flyback resistance that has BOTH a diode and resistor. I need to protect my ECM on a vehicle as the ECM is directly providing the ...
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Makerbase TMC2226 stepper driver board: are current sense resistors underrated power-dissipation-wise?
I am looking at the schematics for Makerbase TMC2226 stepper driver board:
The schematic shows 1/8W 0.11 ohm current sense resistors.
The datasheet for TMC2226 IC says:
8 Selecting Sense Resistors
.....
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Electromagnet with ESP32 and MOSFET
I got this circuit that should drive electromagnet from ESP32 using 1RLZ44N MOSFET. I do think I got it correct but would appreciate feedback. I am a little bit uncertain on the placement of the 10 kΩ ...
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Resistor Values for an LT1170 voltage regulator
I am trying to create a schematic for an LT1170 to make a stable power supply at 13.5V. This is in order to regulate an unregulated wall wart PSU for a older device. The original supply is a ...
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What is this symbol? Looks like a resistor with a solid line below and joining the 2 ends
First timer at attempting board level repair...
I am attempting to fix a motherboard that got damaged by a failed hard drive. There was a dead short between GND and 5v.
I found a burn component that ...
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How to find out the value of +40 years old resistor?
Can anyone tell me the value of this resistor? Now, it is fried so it is not possible to read or measure it. The picture I show here is before the incident. Looks like orange-red-silver-gold which ...
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Explain the circuit inside a rechargeable hair trimmer
I have a small, normal hair trimmer:
This is the circuit inside it:
Some information:
The batteries are two rechargeable Ni-Cd 1.2V batteries.
D1 has 0.7V forward voltage.
LED (marked with "...
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Purpose of big size resistor in pcb
I dismantled a toaster and tried to figure out the purpose of every component.
The heater elements of the toaster forms a voltage divider that gives around 20VAC to the PCB. Then a diode and a cap ...
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Selection of the type of resistors and capacitors
I’m currently working on an ArtNet Node project using a Teensy 4.1 and aiming to build a 3 Universe ArtNet Node with Ethernet connectivity.
Since I will be building the circuit on a breadboard I do ...
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What size resistor do I need to limit current to 50A from a battery? [closed]
I am trying to limit the current flow from a 12 V 275 Ah battery to 50 A.
What size resistor do I need?
I need to limit the current to no more than 50 A to a lithium-ion battery spot welder.
The ...
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Transistor constant current LED photocoupler
I have this shown circuit below and I'd like to have 5 mA constant current on the LED (Vf = 1.2 - 1.4 V), Vcc = 5 V, NPN 2N2222. Some circuit use the Zener diode and other use just a regular diode. ...
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Figuring out how to do Voltage Divider
Here in the Ac analysis section of the CC amplifier we're getting the Gain (Av)
We used voltage divider method for Vb/Vs; I was confused as to why when getting Vb(voltage at base node ) why we didn't ...
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Can anyone help identify this resistor?
To my eyes the stripes look like gold-gold-black, but that doesn't make any sense. Any help would be appreciated.
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I can't identify the component if it's a resistor or axial inductor
I have an adapter (12v 2A) which is broken. i just face that component(indicated by the arrow) and didn't know if it's an axial inductor or a resistor.
I can't find the same colors in any color codes ...
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When current is passed through a wire, does it heat up uniformly, or is there a temperature differential?
When a current is passed through a wire (or a very long resistor), does the wire heat up uniformly? Or does it get hottest at one end and then get hotter down its length, following the flow of the ...
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Using constant current driver and/or resistor for LED
I want to mount some high powered XHP LEDs to a PCB in parallel. If I'm using constant current drivers that are separate from the PCB to drive current into it at the rated voltage of the LEDs, would ...
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Need help with identifying the resistor or probably the problem with the ultrasonic cleaner [closed]
My father was trying to use an ultrasonic cleaner and the fuse blew. I changed the fuse, tried it again and it blew again. Probably something off with the circuit. Then i noticed a resistor is kinda ...
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Do 0-ohm resistors have applications other than as jumpers?
I have a question regarding the use of 0-ohm resistors in electronic circuits. While I know they are commonly used as jumpers to connect different parts of a circuit, I’m curious if there are other ...
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Why isolation resistor on a serial port between MCU and transceiver?
Circuit I've inherited:
Mostly a run of the mill RS485 transceiver. On the right the bus, on the left an STM32.
The 10R are probably some attempt to limit the fault current when the TVS is not enough?...
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Need to figure out the resistor requirements in this parallel circuit
Here's the conundrum, I
need to find out what resistors to use in this circuit,
As I don't know enough about electronics to confidently understand and any help would be greatly appreciated.
The ...
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How to dim push button led switch?
I bought an audio amplifier which has this LED push-button to power it on & off:
The LED is too bright, it's a bit annoying, so I wanted to dim it, but I have no clue how to do that. Would it be ...
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Does this (combined switch/variable resistor) component exist?
I'm looking for a component like this - similar to a potentiometer, but with a gap in the middle of the resistive element. With the wiper on the far left, red is directly connected to green. As the ...
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AC-DC converter resistor identification [duplicate]
This PCB is from the power supply of a standing fan.
The resistor acts like a fuse, having two gold bands in the middle. How can I read it and what is the replacement for it?
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Quadrature encoder interface without capacitor
I have connected Digilent PmodENC board with a rotary shaft encoder to myRIO MXP DIO pin. MyRIO has an internal 40 kOhm pull-up resistor.
On PmodENC board each encoder output has 2 resistors with ...
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What are the functions for the components in this expression pedal port circuit?
This is the design that the Roland A49 MIDI controller uses:
Here is the design I would use if I hadn't seen Roland's design:
What is the function of the extra components?
My thoughts:
The 1k ...
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Will this work to ground a cheap soldering iron?
I have a cheap 220V AC soldering iron with no ground. I am in UK where mains plugs have three pin and where the middle pin is the ground pin. Hence for soldering with sensitive components it may ...
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How does the size of a resistor affect its power usage?
I'm trying to buy an electric stove and am a bit confused. There are two options: 500W and 1000W. They are very basic: just a circuit with a switch (controlled by a thermostat which is adjusted by the ...
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Threshold percentage for power ratings of resistors?
So my textbook says always to use a higher power rating resistor than what the max power that resistor is expected to dissipate, which totally makes sense so the resistor doesn't blow. For example, if ...
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Is there a way to get more than a 0.5 V spread in a 5 V circuit with only a 100 ohm variable resistor?
The FSR I want to use in a circuit only has a usable range between 2-300 ohms, used in a voltage divider circuit with another 200 ohm resistor I get between 2.5 - 3 V out (0.5 V spread). I would like ...
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Diode-Connected load
What does it mean by a small-signal resistor? What is meant by Diode-Connected load in MOSFET? Does it mean that MOSFET act like a diode connected with a load? Then why it is called as small signal ...
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Using one momentary switch for multiple IC's at different pull-up voltage levels
I am modifying a car stereo to add bluetooth support, as part of this I would like to piggy-back onto the existing front panel momentary switches to control the bluetooth module (play/pause, next, ...
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I'm having trouble identifying this resistor
This is from an air compressor circuit board. I can't find it using a resistor calculator online:
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Help understanding resistor filtering out audio output [closed]
In the attached circuit, I have a 1 kHz sine wave input into the traces marked RA-L and RA-L, and then a 1 kHz square wave of similar amplitude input at the blue points after the capacitor and ...
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