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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}\$)

4
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2answers
137 views

Calculating Wattage for Resistor in High Frequency Application?

I am making a MOSFET driving circuit. Frequency : 400 kHz [50% duty cycle] Gate voltage: 12 V Total gate charge : 210 nC as per datasheet IRFP460 Rise time: 100 ns [Q=I*t] Current: 2.1 A Gate ...
1
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1answer
84 views

Understanding 5V to 1.8V UART level-shifting circuit

Hopefully it's OK to ask very basic electronics questions here. I had a TTL 5V UART cable, however the board I had only accepts 1.8V max. So I found some online schematics that uses resistors and a ...
0
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1answer
54 views

Photodiode - circuit questions

I am a bit confused on a few things regarding photodiodes. Here are two circuits that I am referring to: or   For the second circuit the capacitor is not of importance. Here are my fundamental ...
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0answers
91 views

Is the US Power grid's voltage the theoretical maximum? [on hold]

At this point, most of the people on this site who live in America know that the voltage of common power circuits is around 120 volts. My question relates to the use of voltage dividers in a circuit. ...
0
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1answer
95 views

Is this a 4R9 resistor or somthing else?

After a power-peak due to a broken main electricity cable, me and my neigbours got some broken devices. At our house only my motor cycle trickle chargers were connected. And all 3 got broken :(. ...
1
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1answer
16 views

Switching 3.3V with a Raspberry Pi gpio pin

I recently bought an IR Camera for my Raspberry Pi, something like this: https://www.amazon.com/kuman-Raspberry-Camera-Module-Supports/dp/B01ICLLOZ8/ref=mp_s_a_1_17?crid=M3FSU2COLT5W&keywords=ir+...
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2answers
24 views

12 v dc led lights in parallel

I have a 12 v dc power supply 36 watt 3 amp attempting to run 5 12v dc 4 watt led lights in parallel. at first i tried running 5 hallogen lights but figured they were drawing to much power so switched ...
0
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1answer
48 views

How do I calculate the voltage across a capacitor when the source is a square wave?

I have a series RC circuit with R= 2.2K Ohm and C=100 nF, and the voltage supply is a 2.5V peak square wave. And I'm not sure how to calculate the voltage across the capacitor.
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1answer
89 views

Resistor Value Help

I have two resistors that I'm trying to figure the values of. One is black blue silver gold black Second is black orange silver gold black Can anyone help with these values?
2
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1answer
66 views

Finding the broken cicuit in an Xor Gate

I am new to this particular stack site but I feel that this is the most appropriate place to ask my question. -Background- I've been following an online web course called Nand2Tetris that takes you ...
0
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0answers
77 views

Help identifying a variable resistor's function

I have recently acquired a TC Electronics Tube Pilot guitar effect pedal. While exchanging the vacuum tube in it, I noticed that there was a 22k ohm variable resistor on the board. Can anybody tell ...
0
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2answers
36 views

Full Adder Circuit

This circuit is based around the SN74HC283 4 bit full adder. What purpose does the resistor network serve? Will this circuit work without any resistors, i.e. using raw inputs and outputs? ...
0
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1answer
49 views

Wheatstone Bridge - strain gauge sensor

I'm trying to optimize a Wheatstone bridge with a strain gauge sensor and I'm considering all possible wire resistances. The circuit is shown in the following figure: I don't understand the comment ...
0
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2answers
36 views

Calculating resistor values for a Schmitt Trigger and LDR circuit

I am trying to make a light sensing circuit which has hysteresis. I want an op-amp (LM358) to output logic 1 (12v) when the light level rises above 250 lux, and output logic 0 (0v) when the light ...
2
votes
1answer
91 views

DMM can't measure resistor

I'm new to StackExchange. I am trying to repair a Yamaha digital radio tuner model TX540 made in early 1990s. I don't have a schematic. I have been desoldering components and checking them with a DMM ...
0
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3answers
135 views

Why does a capacitor charge faster when there is a diode connected?

In an series RC circuit why does a capacitor charge faster when there is a diode connected in parallel with the resistor? I tested on an oscilloscope, using a square signal and this is what I got. ...
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1answer
72 views

Kirchhoff's laws circuit, How to calculate unknown resistor?

First time here! I got a question on a test that I cant get my head around. How do I calculate value of R2 ? Is it possible ? Thanks in advance !
1
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1answer
87 views

Direction of current flow in resistor networks

We have a simple resistor network \$g\$ with \$5\$ nodes and \$6\$ edges (resistors) as given below: We assume all resistors have the same resistance (say \$1\$ Ohm, so homogeneously distributed ...
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2answers
95 views

Pulling down resistors [closed]

Please i want to know more about the pull down resistor. For a circuit of about 12v, what value of resistor do i need? Simply put, should a pull down resistor be selected according to the voltage of ...
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0answers
91 views

On Infinite square grid of resistors [closed]

What will be the effect of short circuiting i.e joining the \$(n,n)\$ node with \$(n+1,n+1)\$ one, by a simple wire i.e a wire of no resistance. The grid is made up of two different resistance such ...
0
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1answer
34 views

Why a pure resistive AC circuit absorbs power at all times according to this equation

Here is the equation of average power in a pure resistive AC circuit: "Fundamentals of electric circuits - Alexander Sadiku" How this equation imply that the circuit absorbs power all times, I ...
1
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1answer
74 views

Electronics project

I am building a project for my college work which is used to detect the leakage of gas in house. The schematic diagram is given below. 1: I removed the rectifier part because I am using a battery. ...
1
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3answers
69 views

Chop Saw Inrush Current Limiter?

I have a Dewalt Metal cutting abrasive saw that tends to open a breaker on starting up. It draws 75A on startup tripping the magnetic part of the breaker and opening it. This circuit is only to stop ...
0
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0answers
92 views

What is the purpose of a capacitor in an ideal op amp schematics?

I'm trying to understand the purpose of the capacitor C which is in parallel with the resistor R3. Current sources IB are indicative of the current offset which was the part of the lecture we had ...
0
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2answers
78 views

Cause of blowing resistors

Around 10 years ago we bought 3 dimmers for lighting at a venue. In the last year all three showed the same problem: one or multiple resistors of the dimming circuit (6 channels per dimmer, therefore ...
20
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2answers
3k views

What's the purpose of these copper coils with resistors inside them in A Yamaha RX-V396RDS amplifier?

This is an bit of an overly specific question, but I'm curious about the purpose of these coils inside a Yamaha RX-V396RDS amplifier and wondered if anyone could explain what they're for. They appear ...
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3answers
140 views

Resistor network - how do I reduce this?

How do I find the value of this resistor network. Is the 10 ohm resistor in parallel with the 20 ohm resistor? Is the 16 ohm resistor in parallel with the 5 and 20 ohm resistors in series? I can't ...
1
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1answer
41 views

Calculating resistors for an optocoupler controlling a pmos

I want to use a pmos (SI7157DP-T1-GE3, datasheet) as switch - controlled by an optocoupler (TLP291(V4GBTP,SE, datasheet) which is controlled by a teensy 3.6 (3V3 output voltage). Now I'm calculating ...
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0answers
17 views

enc28j60 ordere wrong resistors

i prototype a small board with ENC28j60. Instead of 49.9 resistors I have ordered by mistake 47R ones, What do you think? will it work? It is only 10M ethernet
0
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1answer
77 views

Fan speed control with resistor

Electrician from Australia here. Just having an issue with a heater fan in a bathroom for a client. According to the diagram I have posted, I can wire a second fan up to this and it should all work. ...
0
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0answers
37 views

How to calculate R for an AC load on a 3-ph system

I'm trying to calculate the resistors in an AC dummy load for a 3-ph system. A simplified schematic can be found below. The idea is to switch (with regular AC 1-ph contactors) some resistors on each ...
0
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0answers
73 views

Trapezoidal Rule of Complex RLC Circuit using MATLAB

I am having difficulty trying to figure out how to solve this circuit using the trapezoidal rule. I know how to do so in a first and second order RLC circuit however this particular circuit is giving ...
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3answers
110 views

Battery indicator Circuit

Many of battery indicator circuits are designed using 2 or more leds like in the image above but how to design a simple battery indicator circuit using only RGB LED and transistor for 12v battery ...
0
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1answer
33 views

Limit variable resistance upper bound?

I have a variable resistance, 1K to 1M. As it varies due to external factors, I want to be able to pick a X value in between 1K and 1M so that once it reaches X even if the resistance increases the ...
2
votes
2answers
2k views

Current across a wire with zero potential difference

If there was a circuit connected with a \$50 \,\Omega\$ resistor and a \$5 \, \rm V\$ battery and we measured the voltage across two points of the wire that have no resistor or battery, does it mean ...
0
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0answers
38 views

How to find the effective resistance across the points A and B here?

I had to draw the circuit and take a picture of it as I am not very educated with circuit drawing software. The circuit consists of 5 resistors with their respective resistances written beside them. ...
0
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0answers
31 views

What resistance would I need?

I'm kinda new to PCB design, but here we go: I've created a simple sub-pump water level monitor and it uses a constant 5V from a MOSFET. In the end, it's all monitored by a raspberry pi and I know if ...
0
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2answers
45 views

Small utility heaters

I have found myself needing small heaters, in the 5-10 watt range for various applications in diy projects, preferably powered from 120VAC. The exact wattage is not important, and doesn't have to have ...
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votes
2answers
69 views

XOR gate from resistors

What I want to achieve is a simple circuit that pretty much implements an XOR gate using resistors (not transistors). Is it possible? Edit per request: I am studying possible ways to implement an XOR ...
2
votes
1answer
83 views

Thin film / metal film resistor

I have read various questions and posts, but still I am not sure whether when talking about resistors, thin film means the same as metal film or not. I read the statement that "most of the metal film ...
5
votes
2answers
1k views

Can I use a single resistor for multiple LED with different +ve sources? [duplicate]

In the photo below I would like to use a single resistor after the LEDs, instead of having individual resistors before the LEDs. Is this problematic? Will it work?
0
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3answers
45 views

Resistor in series needed with LED string?

I have an adjustable 24VDC power supply. I have 1W LEDs that I was planning on stringing 7 or 8 in series to get approximately 24V across all of them together. They are rated 3.3-3.8V each. Do I need ...
1
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1answer
69 views

How do I model a resistor array in SPICE?

I am currently building a library of SPICE simulation models that is going to include resistor arrays. These arrays exhibits both absolute tolerances and relative tolerances. Usually, the relative ...
0
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1answer
67 views

Connect 5V straight to resistor straight to ground

I'm very new to electrical engineering in general and picked up an Arduino recently. I have a couple questions: What will happen if I short 5V/3.3V/Digital pin output directly to ground? Will it ...
3
votes
1answer
93 views

Resistors parallel with motor?

A pcb we've been asked to look at has two 15k 1W resistors in parallel with a 15A AC motor. Silly as it sounds, we're a little stumped why they're there. It's probably bloomin' obvious, but we can't ...
0
votes
1answer
47 views

3.3v led and 220v water pump

I have relay connected to raspberry pi that switches the water pump on and off. I would like to add a toggle switch before the relay with a led. When the switch is turned on the led lights up and then ...
0
votes
1answer
81 views

How to set fixed bias on transistor 2N2222 for certain specifications?

I'd like to ask how to set fixed bias for this transistor.. It doesn't seem to be working. If anyone know how to calculate it, please tell me. I wanna adjust two resistor values so that Uce = 5,44V, ...
4
votes
3answers
1k views

Does ATtiny RESET pin need a resistor?

I need to make sure that my ATtiny does not reset unexpectedly. To do that, I am planning on connecting the RESET pin directly to VCC. However, I have heard some places that you need a 10k resistor ...
1
vote
1answer
46 views

Zero-R Resistor on XTAL pins

Looking at the schematics of the STM32F4-Discovery board page 28, whose screenshot is attached below.. there is a Zero Ohms resistor 'R25' which is shown in the circuit with the Crystal. And there is ...
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votes
3answers
75 views

Watts & ohms of resistor [closed]

I want to connect 24 led 3.2v in series with a power supply of 230v dc. Which resistor should I use. Also pls mention watts of the resistor which I can use