# 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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67 views

### Why don’t external boards need a resistor?

I’ve been trying to learn how to use my MPU6050 chip. According to all of the tutorials/diagrams I’ve seen (one pictured below,) I don’t need to put a resistor in front of the MPU6050. Why is that? ...
33 views

### Amplifying sinusoidal signals

How can you use Proteus to design and simulate a circuit for amplifying a sinusoidal signal with an amplitude of 2V? Using Arduino uno and op amp
61 views

### 12 VDC to 6 VDC to power a radio [duplicate]

I have a Grundig radio that requires 6 V and 500 mA negative center pin. It is very sensitive to noisy wall warts, so I want to power it from my very noise-free ham radio 12 V power supply. Can I use ...
314 views

### LEDs lowering my voltage

I'm getting to electronics and I have ran into a big issue. When I connect LEDS to my breadboard in parallel my voltage drops. I read in the past about series decreasing voltage and parallel ...
228 views

### Question about capacitor and resistor in "power on reset circuit"

What I am reading has this circuit: It also has this description: In analog power on reset implementation, the time and voltage threshold factors are characteristic of an analog circuit. The time ...
83 views

### What would be the loop equation for circuit including resistor, diode, light emitting diode?

I am new to electronics. What would be the loop equation for the following circuit? How would I find the current through the LED and the silicon diode in the circuit? Any help would be appreciated.
1 vote
468 views

### Find potential difference between nodes A and B in circuit below

By KVL and KCL Ix = 4A and Iy=Iz=6A The potential difference between A and B = Va - Vb = 6 +8Ix =38V I don't understand how we calculated the potential difference using KVL and KCL
288 views

### Line level to microphone level to record

I have a digital piano with an earphone output where I can connect a simple earphone (like in the picture below.) It works fine. I would like to connect this earphone output to my smartphone jack (...
1 vote
464 views

### Why does my resistor start smoking when current runs through my circuit?

This is my circuit: simulate this circuit – Schematic created using CircuitLab However, when I wire it up, R2 starts smoking - why does this happen? [Edited to remove incorrect wire]
1 vote
63 views

### Analysis of circuit with dependent voltage source with no apparent solution

This is an exercise from Irwin's book, 9th edition. simulate this circuit – Schematic created using CircuitLab Although the book calls for the use of nodal analysis, I decided to do it by mesh ...
652 views

### Finding replacements for these "big grey" resistors in a circuit

I have a resistor that I need to replace that looks like this (4 color band resistor that is significantly bigger than the others) : If I can read the colours correctly (brown / black / gold / gold) ...
6k views

### Why is a 220 Ω resistor for this LED suggested if Ohm's law seems to say much less is required?

I am a beginner in electronics, so have mercy on me lol. I have been interested in this particular switch with a built in LED here https://www.adafruit.com/product/1476. According to the website, the ...
44 views

### Situation with controlled source in Mesh Analysis. Situations without solution?

I was analyzing the circuit below, and by using Mesh Analysis (this I am currently practicing), I obtained that the voltage at the $6k\Omega$ resistor (R6) is $9V$. I was able to work this out and ...
19 views

### Will a resistor used for an indicator LED in latching pushbutton negatively impact APA102 LED performance in same circuit?

Just to give a little more context to the picture below, I currently have designed a PCB that I will solder/reflow with APA102 2020 LEDs which will work in conjunction with mechanical switches also on ...
1 vote
65 views

### High-voltage resistors versus anti-surge resistors

I am making a voltage divider with four 1M 1206 thick-film resistors and a single 2.7k resistor. The input to this voltage divider will be mains line and neutral. I want to measure the voltage at line ...
353 views

### Using 74HC154 with LEDS current resistor

I am using a 74HC154 to control 10 LEDs in a design. Since only one LED will be on at a time I wanted to use one resistor rather than a resistor per LED. Is there any difference between the two ...
338 views

### How do I wire a Shure WL 185 to to iPhone or iPad?

I have this old but very nice mic. Old days I recorded audio to the camera or recorder. Nowadays I record to iPhone so I do not have extra recording device and cameras are action cameras usually ...
163 views

### Transient analysis of a step RL circuit

In the above problem for t>0 the inductor can be modelled as a short circuit and therefore the current flowing through it is -4/8 or -0.5 A, as no current flows through the 4 ohm resistor. But to ...
435 views

### Any difference in parallel and row resistor circuit?

My goal is to create a 1.5 ohm resistor. I have 2 ohm and 1 ohm ones on hand. My idea was either to create two 3 ohm resistors to connect them in parallel or connect them in row. See picture below for ...
81 views

### Dual potentiometer the solution?

I'm working on retrofitting '14 Lincoln MKS 14 way power heated/cooled seats into a 2002 4Runner. I have all motors & lumbar wired. Had a Eureka moment on the TED and got it working! 3 position on/...
270 views

### Is it possible to have phase shift with only passive (resistor, cap, inductor) components?

I know that this can be done somewhat because voltage will lag current on a capacitor etc. But I want to see if it is possible to take an AC signal and output the same signal but with some chosen ...
27 views

### Implementation of a 24 hour variable resistive load fluctuation

I am implementing a DC microgrid with a variable resistive load variation of 24-hours, based on a load profile. I have implemented it in MATLAB through a variable resistor and a 1-D block to provide ...
112 views

### General statement about arbitrary two-port resistor networks

Suppose I have a resistor mesh that is acting as a two-port network. I'm feeding in $V_\text{IN}(t)$ and I'm reading out $V_\text{OUT}(t)$. Here's an example of a potential circuit: Is it true ...
1 vote
3k views

### Current limiting resistor on peltier element

I have a 12v/22A DC switching power supply and 9 peltier elements rated for 12v/6A. I would like to limit current to 2A per peltier element. I don't know how to calculate the impedance (in ohms) ...
2k views

### What's the use of the 100 kΩ resistors in this schematic?

I saw a schematic for measuring AC voltage on a 3-phase mains supply (R/Y/B are the 3 phases and N is the neutral) I understand that the 1 MΩ and 2.7 kΩ resistors are for stepping down the voltage (...
54 views

### How to choose component values for a JFET common-source amplifier?

I am trying to design a simple common source jfet amplifier using a J109 transistor. I'm using the J109 datasheet and equations from the book Electronic Devices by Thomas L. Floyd. The issue is that I ...
1 vote
344 views

### Disconnecting a resistor out of parallel with a switch

I'm modifying an existing circuit. In order to perform this modification, I need to tap a resistor in the circuit and put another in parallel. By connecting this resistor in parallel (changing the ...
604 views

### Drive in movie speaker via bluetooth and mini amp

I need some technical help that I believe a site like this could answer. I bought some drive-in movie speakers which I restored by cleaning up and replacing the old 4" drivers.The 2 drivers are 4&...
1 vote
926 views

### Find the transfer function of the circuit if current I is the measured output

So there's this problem I am trying to solve: Consider a series RL circuit corrected to a DC voltage source and an on-off switch. Assume R = 2 ohms, and L = 1H, and applied voltage V = 10 volts. ...
42 views

### Equivalent resistance in simple Current Circuit

I have the following circuit (below). In order to calculate the current I1 as a function of the resistors and the voltage of the circuit, I'm doing the following: ...
142 views

### LED resistor basic wiring [closed]

I am looking for a single BRIGHT LED light. I'm using: 1 red 5mm LED AC adapter of 5V 2.5 amps 1 ohm resistor It works, but doesn't seem very bright. Am I correct or completely wrong? What is the ...
56 views

### CAN Bus termination resistor in only 2 device connection

A termination resistor in CAN ( .. or other differential pair communication like RS485 ) is necessary to absorb reflection. The value is related to wire length, electrical frequency, baud rate. It ...
5k views

### Replacing resistors with equivalent resistor

This is somewhat a homework assignment, but please bear with me. Given the following schematic, I want to know the overall resistance when measured from node A to node B. simulate this circuit –...
62 views

### First-order RC circuit

I have a first-order RC circuit without source and capacitors initially charged to +5 V and -4 V as shown in the figure. Initially charge sharing takes place between capacitors and v(a) = v(b) = 0.5 V....
7k views

### What resistance/load do battery testers (AA or AAA) use in ohms?

I am trying to find out what size resistors an AA or AAA battery tester would use? I have tried searching but am unable to find an answer. I mean testing alkaline and NiMH 1.5 V and 1.2 V batteries, ...
453 views

### Order of an RC circuit

The circuit contains two independent state variables but the output of the circuit simulated in LT spice shows a first-order response. Where am I wrong?
47 views

### Resistor Power Rating and Pulses

I'm really confused with resistor power rating and pulses. I'm trying to determine the power rating of a resistor that will receive pulses of potentially 40 volts for 15 milliseconds. During this ...
125 views

### Why does voltage decrease as resistor increases?

As you can see in the images below, when I increase the resistor value from 200 Ω to 2 kΩ, the voltage at the node Vd suddenly decreases. Why is this so?
1 vote
92 views

### Understanding pull-up/down resistors for a GPIO pin

I'm a total beginner, trying to find my way through basic electronics... I went over some written material and YouTube courses, but there is something I don't think I get right. Consider my case - I ...
270 views

### What component should I use? H-bridge? Relay?

I am working on a senior design project that involves regulating the noise from headphones to make sure no damage to the ear is done. I have all parts working except the part necessary to switch the ...
224 views

### Reducing speed of motor in cheap record player

I bought a cheap record player, and it is spinning too fast. It is using a 12V 1Ainput with what I believe is a cheap Chinese 12V motor for turning the belt. There is a pitch control on the turntable, ...
1 vote
94 views

### Changing LED from blue to yellow (car ambient lighting) - what is the purpose of the resistors?

I've got what looks like a fairly simple circuit I've pulled from a car door card. It provides variable brightness ambient lighting in blue, which I want to change to yellow for aesthetic reasons. I'm ...
1 vote
948 views

### How do I choose the power rating of resistors in audio power amplifier?

I read a bit about audio power amplifiers and struggle to understand the power rating of the emitter (i.e. current sharing) resistors in power amplifiers. I refer to this project. Schematics and BOM ...
1 vote
127 views

### Three LEDs on consecutively with different time intervals

The title is referring to a youtube video if a 555 and CD4017 led larson scanner but this circuit only allows the LED to be on at the same time interval. Is there a circuit which can help to activate ...
84 views

### Check if bucket has water left

I want to build starter and simple auto self-watering system. I need the pump to take the water from a bucket, which means I need to check the water level on it and alert if too low. I want to do it ...
72 views

### Series/Parallel Resistor Association

My question is very direct. I understand the definitions and formulas involved in the association of resistors in both series and parallel, but when solving the circuit below, I don't quite understand ...
1 vote
858 views

### Differential equation for trivial RL series circuit

I would like to obtain differential equation describing behaviour of this circuit. I'm really new to this and not quite sure how to begin. We can consider situation of knowing values of all parameters ...
78 views

### What value resistor is this? [duplicate]

I'd like to change this resistor from a main board but I'm not sure about its value. It's marked as 0.2R in the datasheet (so 0.2 Ω) but following the color code it should be 22.88 Ω. Am I right or I'...
1 vote