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}\$)

Filter by
Sorted by
Tagged with
0 votes
1 answer
35 views

Power Rating of a HV resistor

I am conducting a project to measure Breakdown Voltage and would like to use a protection resistor, please see below. When breakdown happens I will have something like In this case the Power ...
user avatar
0 votes
1 answer
36 views

Do I need a current limiting resistor with an industrial rail DIN optocoupler?

I'm going to use this industrial opto-coupler: Optocoupleur RS PRO, montage Rail DIN, 6 mA In its specs document they don't mention the need of a current limiting resistor. I always add a current ...
user avatar
  • 245
1 vote
1 answer
78 views

What happens if a ceramic power resistor is heated well past its rating?

What would likely happen if a ceramic power resistor was powered well over its power rating (for test/learning purposes and likely buried inside a bucket of sand)? By "well over", I mean 10 ...
user avatar
0 votes
0 answers
61 views

Activate arc lighter with Arduino

I have a SaberLight plasma arc lighter, and I have taken it apart for a flamethrower project. I would like to use an Arduino Uno to programmatically activate the arc lighter. Using the Arduino Uno, ...
user avatar
15 votes
2 answers
1k views

Which way to read this five band resistor?

Sorry for this basic question. I have a problem determining which way I should read band on the resistor below. I know it's left to right, but which side of it really is "left"? As far as I ...
user avatar
  • 430
-1 votes
1 answer
57 views

Can I use lower wattage resistor if I’m using a high voltage power supply?

I can use a higher gauge wire with the same wattage if I use a higher voltage so the current is lower. Can I do the same with resistors? I have a neon sign transformer that’s 450 watts at 15 kV and 30 ...
user avatar
0 votes
2 answers
59 views

Will a resistor reduce voltage without current flow?

I asked a question where I was trying to figure out how my truck controls the speed of its blower motor. This answer provided the following diagram showing that it uses a set of resistors in series to ...
user avatar
  • 127
1 vote
6 answers
148 views

How to reduce power drawn by a resistor heater?

I am rather new in this field. On 220V AC industrial power supply, a 6 ohm resistor heater (nichrome wire, 0.40 ohm/m, 15 m) will draw about 8067 watt of power. About 2400 W are needed. What are the ...
user avatar
  • 49
1 vote
1 answer
36 views

Finding the "drop in potential" as current moves through a single resistor of a circuit with parallel resistors

I have four different resistors connected in parallel to a \$24.0 \ \text{V}\$ battery with internal resistance of \$0.500 \ \Omega\$. The resistor values are \$10.0 \ \Omega\$,\$15.0 \ \Omega\$, \$30....
user avatar
  • 1,201
1 vote
1 answer
53 views

Using a potentiometer to shift between negative outputs from either -2V and 2V

The question that I am wanting to ask is that I start off with either 5V or -5V which is reduced to -2V or 2V for my output for the potentiometer. My potentiometer has a 5k resistance and I am trying ...
user avatar
3 votes
2 answers
929 views

Why is capacitor discharge time higher when an LED is included?

I'm testing the discharge time of a capacitor. I found that the time is higher when an LED is present. Circuit with a capacitance of 100mF, 10k resistance and 5V voltage. By calculating discharge ...
user avatar
6 votes
1 answer
183 views

XKCD 356 puzzle

I was reading XKCD and saw this comic: Turns out it works, and have been thinking about this for an hour and have gotten nowhere. My first thought was to find the resistance of all paths of length ...
user avatar
1 vote
2 answers
44 views

Finding the voltage available at the terminals of the battery in a circuit with parallel resistors

I have four different resistors connected in parallel to a \$24.0 \ \text{V}\$ battery with internal resistance of \$0.500 \ \Omega\$. The resistor values are \$10.0 \ \Omega\$,\$15.0 \ \Omega\$, \$30....
user avatar
  • 1,201
1 vote
1 answer
70 views

Finding resistance for parallel resistors: how is my reasoning incorrect, and what is the correct reasoning?

I have the following circuit: The voltmeter \$V_1\$ measures the voltage drop across the \$9.00 \ \Omega\$ resistor and has a reading of \$4.50 \ \text{V}\$. The reading on ammeter \$A_1\$ is \$I_1 =...
user avatar
  • 1,201
1 vote
3 answers
121 views

What limits the heating power output of a resistor heater?

I'm a bit confused since people said those resistors would draw more power the lower its resistance is, and one way to reduce its resistance is reduce its length. Will it draw more power the shorter ...
user avatar
  • 49
2 votes
0 answers
61 views

How to wire one switch that can turn on/off two independent switches [closed]

In my car I wired in a Front View Camera (Camera-A) that has it's own toggle switch (S-A) to manually turn it on/off, and has it's video displays on my Head Units Display. I also wired a Backup Camera ...
user avatar
0 votes
0 answers
62 views

What wattage should the resistors or pots be in a car audio voltage divider?

My new radio amplifies the output too much and my car stock amplifier is non-adjustable. The only solution (that I know) besides putting the stock stereo back in, is 4 voltage dividers. I'd like to ...
user avatar
  • 1
0 votes
2 answers
59 views

Should I use a resistor in series when connecting a pin to logic level high?

I'm trying to design a circuit with MAX8934AETI+. I'm confused about how to connect a pin to logic level high. For example, pin 6 in the picture below is meant to be connected to logic level high to ...
user avatar
-2 votes
2 answers
74 views

How to use resistors to lower voltage? [closed]

I want to use a resistor to lower 3V to 1.8V but I'm not sure which one to use. How do I decide which one I should use?
user avatar
0 votes
3 answers
37 views

What is the tradeoff in decreasing the frequency bandwidth when reducing noise of a resistor?

A resistor's Johnson (Inherent) noise can be modelled as an RMS voltage in series with the resistor: $$ e_{rms}\triangleq\sqrt{4kRT\Delta f} $$ where k is Boltzmann's constant, R is resistance, T is ...
user avatar
  • 197
3 votes
3 answers
107 views

Driving a LED with a potentiometer in parallel, electronic basics

Today, in class, we were to analyze this circuit: simulate this circuit – Schematic created using CircuitLab And calculate \$\alpha \in [0, 1]\$ associated with R2 a potentiometer. I'm confused ...
user avatar
  • 37
0 votes
3 answers
101 views

Resistance measured individually vs measured on PCB

I always wanted to ask this question. Suppose I have a 1kohm resistor. I measure its resistance by connection a multimeter to both of its terminals (when it is not connected to any part of a circuit.) ...
user avatar
  • 2,198
3 votes
1 answer
92 views

Which temperature sensitive material would be a good choice for temperature measurement from 4K to 300K?

I am building a thermometer for a cryostat which operates at low temperatures (until 4 kelvin). I would like to know the temperature of some parts in my cryostat during the cooling (so from 300 K to 4 ...
user avatar
2 votes
4 answers
141 views

How can I best reduce the current drawn by a PCB heatbed?

I have a noob question about fairly basic circuit design (I think). I am building an incubator for making Tempeh at home, and want to use an old PCB heatbed I have lying around as the heating element. ...
user avatar
6 votes
2 answers
360 views

Selecting series resistor for a Zener diode

I am currently designing a device that will be powered by eight AA disposable batteries. For reverse polarity protection I am looking to use a P-channel MOSFET in the following configuration: ...
user avatar
  • 61
0 votes
1 answer
113 views

Can the connection of collector and base in these circuits be considered as a diode connected transistor?

I was learning how to design an op amp and I saw something thatis called "diode connected transistor." Like this image: Later I saw a person that was teaching about these circuits, and he ...
user avatar
  • 75
0 votes
2 answers
302 views

How to find the voltage on each of the parallel resistors? [duplicate]

Suppose we have a circuit like this: It is easy to find the voltage on the node shared by the two parallel resistors, we simply have to find their equivalent resistance and use KVL. But the problem ...
user avatar
1 vote
6 answers
152 views

RC time delay circuit to trigger relay

I'm trying to design a circuit that uses a momentary switch/push button to turn on an LED, then it turns off after 1 sec if the switch is held in the ON position longer than that. Below is a diagram ...
user avatar
  • 43
3 votes
2 answers
88 views

Is a current limiting resistor needed for dual opamp supply pins?

Consider the TL072 dual op amp that is supplied with +/- 12V. The datasheet says that the supply current for (each) amplifier is typically 1.4 mA, with maximum of 2.5 mA. If both amplifiers are ...
user avatar
  • 519
0 votes
2 answers
35 views

Power Supply Module Internal Trimmer circuit / Remote Programming Resistor Value?

I am looking to incorporate a 45V supply into a design. These PFE1000-48V supplies have a trimming ability to get +/- 20%, based on +/- 20% variable resistor. I am trying to confirm what this resistor ...
user avatar
  • 5
0 votes
1 answer
62 views

Feedback resistor and capacitor calculation for transimpedance amplifier

I am designing a transimpedance amplifier using LTC6268-10 from Analog Devices. The photodiode that I use is S9055-01 from Hamamatsu and the laser source that I use has a power of 10mW with the ...
user avatar
4 votes
4 answers
607 views

0 current in a circuit using tunnel diode

Suppose we have a diode with negative differential resistance of -40 ohm in the region of 0.3-0.5 V and we put it in parallel with a 40 ohm resistor: simulate this circuit – Schematic created ...
user avatar
-1 votes
1 answer
31 views

Need help lowering 5.5V to 3V for my GPIO input

So I'm new to electronics and sorry for the cursed images of circuits, but I have a background in computer science and trying to make this work. So I took the connection from my Intercom bell and it's ...
user avatar
13 votes
5 answers
2k views

Why do the leads of some resistors have holes?

Why do the leads of some resistors have holes? Is it to: Run a wire through it before soldering? If so, what is the best technique? Run a tiny screw through it for connecting a tiny lug? Provide a ...
user avatar
0 votes
0 answers
30 views

Analog to digital conversion for neural network weights

I am a machine learning researcher, and lately I am getting interested in neural networks trained on analog hardware. However, I have some doubts about their potential, probably because I am missing ...
user avatar
  • 101
1 vote
1 answer
54 views

Are these trim potentiometer measurements expected? [closed]

I am trying to replace a 2-D analog joystick assembly that no longer works, because I dropped it. The assembly looks just like the one pictured in this forum post. My question is about the trim ...
user avatar
6 votes
4 answers
1k views

Tiny inductors and capacitors connected in parallel to a DC motor terminals

Why would you connect tiny resistors and capacitors in parallel to a DC motor as shown in the picture? Why would two of the resistors be connected to the outer shell of the motor? I checked the ...
user avatar
  • 179
3 votes
1 answer
54 views

Calculating optimal resistor values for an ATtiny84A circuit and NPN transistor vs MOSFET

I am starting my first project in electronics and I am having a hard time understanding the information available in the 84A's datasheet (pg. 179, Electrical Characteristics) While drawing the ...
user avatar
1 vote
0 answers
44 views

Can I connect low-power resistors to achieve a high-power resistive load?

I've designed an 80 W 400 V PFC boost converter and I want to test it with resistive load. but I couldn't find a low-cost high power (20 to 80 watts) resistor in the range of 2k to 10k ohm. Is there ...
user avatar
  • 457
4 votes
3 answers
331 views

Voltage Based Current Limiting Application

I have a mobile application where I need to pre-charge the capacitors in a Victron 24v MultiPlus with a resistor before closing the circuit switch to its battery bank (24V 200Ah lithium); this ...
user avatar
  • 171
-1 votes
1 answer
58 views

Find time in RC circut with known C and R

In a series RC circuit with a voltage source the Capacitance(15uF) and Resistanse(22.4ohm) is given. The time at which the Voltage across the resistor is same as the voltage across the capacitor is ...
user avatar
9 votes
5 answers
2k views

What is the reason to connect 4 resistors of the same value as 2s2p? (image)

There are 2 parallel branches, each has 2x 10R resistor. It seems to me that the resulting value will be 10R, but I can't wrap my head around why would someone do this if it is not meant to dissipate ...
user avatar
  • 93
1 vote
1 answer
49 views

Level shifting of a 3 state pin

I want to design a simple battery charger using MCP73831/2. This chip has a 3-State state pin according to the table below: I have a 3.3V MCU and I want to connect this pin to a GPIO. The MCU is not ...
user avatar
  • 555
-3 votes
2 answers
54 views

Computing voltages over resistors [closed]

How do you use the combine/redraw method to find the voltages of the different resistors?
user avatar
  • 1
2 votes
1 answer
42 views

PWM Controlled Resistance vs Resistor to minimize heat dissapation

I have a low-ohm resistor (7.5 ohms) connected to a MOSFET used for passive charge balancing. It is generating a lot of heat on my PCB. I can apply a duty cycle to the switching which somewhat combats ...
user avatar
1 vote
4 answers
64 views

Parallel RC Circuit Time Constant

For a general RC circuit that looks like the following: (Sorry for the rough sketch of the circuit, I couldn't find a picture online) What would the time constant or RC equations be? My thinking: The ...
user avatar
1 vote
1 answer
55 views

Load testing using a resistor bank

I have a bespoke 48V down converter that I'm looking to test which should be able to provide a maximum of 500W of power. I'm looking to test the device under various loads - from 50W to 500W. I'm ...
user avatar
1 vote
1 answer
57 views

Dependent voltage source in RL circuit

In this question, V1 is a dependent voltage source. The question asks us to calculate i(t) and ix(t). Assume that \$ i(0)= 10 A \$ for the inductor. I decided to make mesh analysis. Mesh 1: $$0.5\...
user avatar
  • 111
1 vote
1 answer
44 views

Measure Magnetic Field Circuit

I saw a design of a magnetic field meter circuit at here.This circuit looks like it can measure weak magnetic field such as earth's with only using inductor coil to gather magnetic field and without ...
user avatar
0 votes
2 answers
51 views

Using resistor with 110 V LED indicator to make current measurement between 50 - 70 mA

I need your guidance with the V=IR formula. It's probably a simple question but I don't have an electrical background. I am working on making an LED simulator panel for railway signaling interlocking ...
user avatar
  • 3

1
2 3 4 5
77