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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}\$)

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1answer
32 views

Check for 12V with Arduino (Two resistors and a diode)

I need to read the presence of 12V on one of the lines of the board. I want to read using Arduino UNO. I found the following scheme: Is this scheme correct?
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2answers
31 views

Derivation of time constant for single source, single capacitor RC circuit

Take a circuit comprised of resistors, a single capacitor, and a single step response voltage source. Then: Every single voltage and current in the circuit, except at the voltage source, will have a *...
11
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2answers
1k views

Help With Resistor Type? [on hold]

Im having a hard time finding the spects for this piece I know is a metal film resistor, according to the colors its a 470? is this correct, does anybody know where can I purchase a ton of this?
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2answers
65 views

Conceptual paradox with resistance in loop/node analysis

There are loop/mesh analysis and node analysis corresponding to Kirchhoff’s voltage law (KVL) and Kirchhoff’s current law (KCL), respectively. Let's consider three elements, R,L,C, connected ...
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1answer
43 views

Time Constant of a Complex RC Circuit

I'm trying to model a diode as two capacitances, a conductance, and a series resistance, as shown here: In order to generate an expression for the capacitance I'm equating 1/w3db to the time constant ...
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1answer
43 views

Effect of changing current sense resistor value in amplifier circuit

I am trying to implement a current output amplifier circuit shown below. Current is measured across sense resistor Rs to adjust input voltage Vin. Gain: G = -Iout/Vin = R2/(Gain-of-IA1*R1*RS) The ...
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1answer
58 views

Resistor between GND and + 5V in Arduino

I design a board based on ATMEGA328P (as in Arduino UNO). Now I am busy creating a power line. My controller will be installed on the electrical panel, so I need to provide a reliable, noise-resistant ...
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0answers
46 views

Trouble identifying component

I have a cracked what looks like a surface resistor and it only has a 2 digit number code. I can only find identification tables for either 3 digits or 2 digits with a multiplier letter. Can ...
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3answers
160 views

How can I create voltmeter with Zener diodes?

simulate this circuit – Schematic created using CircuitLab 5 LEDS One LED is to remain always on when current is passed through. One LED will turn on when voltage is between 50 to 90 volts. ...
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1answer
45 views

Buffer with TL084CN and resistors

simulate this circuit – Schematic created using CircuitLab There are two buffers made with the TL084CN, which is part of the conditioning of an LTS25-P transformer. Currently, I have put a ...
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0answers
38 views

Confusion between resistors and their names [duplicate]

How are these components different from each other 1.Variable resistor 2.Rheostat 3. Potentiometer
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2answers
139 views

What is wrong with this voltage shifter?

I need to do voltage shifting (3.3V Papilio FPGA <--> 5V RAM chip). Most of the pins are output 3.3V -> input 5V, and 3.3V qualifies as "high" to a 5V device, so I can connect them directly. The ...
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1answer
41 views

Admittance of the impedance of R and C in series?

I have a resistor \$R=150\$ and a capacitance \$C=\frac{1}{750\omega}\$ in series: \$ Z=R-jX=R-j\frac{1}{\omega C}=150-j750 \$ If I take the admittance I have \$Y=\frac{1}{Z}=\frac{1}{R-jX}=\frac{...
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1answer
85 views

Identifying a resistor with a weird band combination

I am currently in the process of trying to repair a power supply that has had one of its DC rails fail. A resistor in the PSU has exploded and I am trying to find what value it is. Band 1: White Band ...
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0answers
30 views

High current low voltage MOSFET help

I am wondering if I have a 75 amp @7.4v source, obviously it's gonna be hard to find a switch with a 12 mm thread to handle that power, so I would obviously need some kind of MOSFET. My question is, ...
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0answers
51 views

Ideal diode IV characteristics

If I know that the Ideal Diode only allows current to flow once V > 0, how would I go about implementing the two resistors into the IV graph? How do I analyse the circuit as a whole IV graph?
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2answers
61 views

How to measure 2.5 volts out of 5 volts and serial resistors?

I have a circuit that's being run from a 5v and is essentially a series of resistors. I want to be able to "tap" it to get 2.5v - 3v out of it, which I think would be straightforward, but I want to do ...
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1answer
54 views

Converting pre-lit Christmas tree with incandescent mini-lights to use LEDs

This might be a dumb question, but has anyone been able to successfully convert a built-in incandescent mini-light string to use LEDs? I have a few of these pre-lit burgundy-colored tinsel Christmas ...
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2answers
59 views

Voltage across capacitor in charging RC circuit with constant current source

simulate this circuit – Schematic created using CircuitLab I couldn't really figure out how to get the switch that I wanted but this is functionally the same. Before the switch flips, there's ...
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2answers
58 views

Equivalent circuits with one or multiple resistors

I am designing a circuit but I am facing a repetitive design that require too many resistors. The problem comes down to answering if the next two circuits are equivalent in terms of voltage drops: ...
5
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1answer
609 views

Do SMD resistors have to be reflowed black side up, or is black side down okay?

I reflow my own boards in a toaster oven. When I drop my resistors off the paper tape, I always flip them over to black side up before I place them. Should I bother if it doesn't really matter?
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3answers
102 views

How far can a terminating resistor be from the literal end of a CAN bus?

I'm wondering if anyone knows if there is an upper limit for the distance a terminating resistor can be from the literal end of the CAN bus or where the last node is. We have an HMI that is connected ...
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1answer
53 views

LDO Voltage regulator output unexpected Voltage drop

I have a circuit using LD39015 1.2V Low Drop-out voltage regulator. . The value of VCC is 3.3 Volts. The goal is to supply an ADC channel with a constant stable voltage so I can use that to ...
1
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1answer
187 views

Identifying strange burnt resistor color code

I'm trying to figure out the resistance of a burnt resistor in the PCB of a Hoover FD22G 011 (a cordless vacuum cleaner, with rotating brush; should be the same as the Deik ZB1516, which is the actual ...
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1answer
42 views

Interpreting a datasheet of resistor for heat sink

I will have this 47k 50W wire wound resistor which will be across line and neutral which means 230 VAC rms. So the electrical power in theory will be V^2/R = 1.2 Watt. How should one interpret this ...
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1answer
80 views

Help simply the resistor usage in this voltage summer and divider circuit

Can someone help simplify the resistor usage in this circuit? VS is a constant 5v supply. Flex is a variable voltage between 0 and 5v. The resistors above have been brute forced to achieve this ...
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1answer
48 views

stall dc motor 12 volt for long time

hi every one i make water cooling system for dc motor 12 volt how can i make the dc motor hot to test the system ? whan i stall the dc motor the wires get very hot before that effect the motor and i ...
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3answers
108 views

Resistor selection based on power rating

For example, I have a cicuit of single resistor R = 2k, apply with Vdc = 18V. The Power of the resistor is about 162mW. Should I pick a resistor with higher Power rating (Eg 0.25W 0.5W) or lower ...
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2answers
115 views

Uses for 49.9Ω resistors? [duplicate]

It seems that both 49.9Ω and 50Ω resistors are a thing: https://www.mouser.co.uk/Passive-Components/Resistors//N-5g9n?P=1z0wnltZ1z0wljo https://www.mouser.co.uk/Passive-Components/Resistors//N-5g9n?P=...
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2answers
92 views

Why do different resistors of the same power rating burn out / not burn out?

I have a circuit board for a small LED light, which comes with an annoying strobe mode. To disable this I have found that I can wire a resistor from a pin on a chip to ground and the LED will stay in ...
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1answer
65 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
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2answers
61 views

Four-terminal resistor pinout?

Anyone can tell me (or preferably, point me to a source that explicitly shows) the pinout of the 4-pin current-sense resistors? I'm seeing the datasheets for three different models (including Rideon'...
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0answers
40 views

Window maker basic circuit question

I am in a basic electronic laboratory and we are working on an ON/OFF analog switch lab. Here the first subsystem is shown and basically it introduces the idea of a upper and lower limit window with a ...
2
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1answer
67 views

Are resistor networks appropriate for voltage divider?

I need to make 9 voltage dividers in order to connect 9 resistive sensors to the analog inputs of an Arduino board. I was tempted to use a 10K resistor network to individually ground the inputs but ...
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1answer
37 views

Load current computation of complicated resistance network

I'm reading Electronic Principles 6th edition by Malvino. Problem 1.28 describes a network of resistors that I would like to know how to solve mathematically instead of experimentally (as described in ...
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2answers
70 views

Swap between two colors without an additional light?

A Quick Note I'm not sure of a more accurate name for this question. If you can think of a better name, feel free to edit and change the name. Also, I'm not the greatest with technical terminology so ...
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2answers
123 views

Do i need a resistor in this led circuit?

I have made a circuit with two (3v) LEDs in series. Connected to a 5v supply from an adapter with usb. (1.5Amp) I belive in series circuit each led gets around 2.5v which was enough to light them. ...
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2answers
26 views

Thévenin's theorem exercise, resistances

I've some problem identifying the \$R_{th}\$ simulate this circuit – Schematic created using CircuitLab Removing the load and short circuiting the Voltage source we get : simulate this ...
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1answer
71 views

How do I go about solving this and finding the value of v(t)?

I'm very sorry if the solution turns out to be very basic, but I'm a very recent student and my teacher is less than happy to help. edit: sorry for not posting my attempted solutions first. Here is ...
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1answer
33 views

Thevenine equivalent using loops

I'm trying to figure out the Thevenine resistance of this circuit using loops. Perhaps loops is the wrong way to go? I've made the circuit using a breadboard and found out that the answer should be \$...
5
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2answers
865 views

Why are the resistors in an AM modulator necessary?

In preparation for the amateur radio exam, I have been following the preparation course material by DJ4UF. In the section about modulation it presents this diagram of a simplified AM modulator. The ...
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4answers
124 views

Arduino: read different voltage values in a range from -12 to +12V

I would like to trigger different functions in Arduino related to the following voltage values: -12V, 0V, 6V, 9V, 12V (the range is from -12V to +12V). According to the value of the voltage read (-...
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1answer
39 views

Debouncing IC input resistor?

I've recently been working on a breadboard compatible compact debouncing PCB. I found the MAX6816, a debouncing IC - check the spreadsheet here. I made the below simple circuit as per the "Typical ...
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1answer
66 views

How to find these resistance values in microphone phantom power power supply?

In most phantom power supply schematics or documentation (see for example https://en.wikipedia.org/wiki/Phantom_power#Technical_information), I see: 6.81 kΩ when powered by 48V 1.2 kΩ when powered by ...
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3answers
60 views

One resistor in series and two in parallel for LEDs

So I've read that using one resistor to limit current to two or more LED's in parallel is bad practice, so I wondered what about this kind of circuit: Is this also bad practice? Each LED has it's ...
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1answer
49 views

How do I connect an oscilloscope to a power supply or function gen.?

I'm supposed to sketch a circuit for my class but the one thing that has me completely confused is the ground connection. For example: I have a breadboard with a 10V dc power supply and two ...
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1answer
56 views

Resistor values for OpAmp circuit with dc offset applied to inverting pin

$$ \newcommand{\rth}{R_{TH}} \newcommand{\vth}{V_{TH}} \newcommand{\rf}{R_{F}} $$ Asked this in the math stack exchange, who recommended asking here instead. I'm stumped (hence posting here!) with ...
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1answer
59 views

Leds in series with buzzer without resistor

So I'm pretty new at this, so I'm sorry for any dumb questions/statements. I'm trying to build a puzzle box where you activate a circuit with a reed switch using a hidden magnet. Activating this ...
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1answer
24 views

Array Resistor Temperature Coefficient

This resistor array is provided with a +/-200ppm/°C temperature drift. I understand that is the maximal allowed drift. However, does it means, within in single package array, is it likely that all ...
1
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1answer
74 views

Why do these two resistor networks measure differently?

Why do these two resistor networks measure differently? Aren't two 100k resistors in series supposed to be equivalent to a single 200k resistor? These are being simulated with Circuit Wizard.