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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circut.diagram , calculating voltage drop and how many ohms resistors are needed [on hold]

for 5 white, 1/2 watt leds with a power supply of minimum 5 volts ..how many resistors and how many ohms each a resistor would I need .....please draw a circuit diagram with the given details and ...
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2answers
20 views

Cermet potentiometer temperature coefficients

I'm engineering a system that is temperature-sensitive, between ~-10-30C. I've moved to using cermet potentiometers because of their sub-200PPM/C temperature coefficients. If I wire such a pot with ...
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1answer
160 views

AVR switch best practice

After reading a lot of posts (here and on the web), I am a bit confused. All I want to do is to get the best practice of push button connection to AVR. I have 2 "sections" to my question. the first ...
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1answer
50 views

About finding equivalent resistance

The figure below is the schematic of the circuit, I have to admit that this is a homework question which I have stuck for a while. I try to use Wheatstone Bridge theory, but here in this question ...
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1answer
39 views

Negative resistance in Thevenin equivalent using elementary devices?

Is it possible to generate a negative resistance Thevenin equivalent using just resistances, ideal voltage sources, ideal current sources? I need a negative slope straight line I with respect to V. ...
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3answers
78 views

One resistor on two LEDs [duplicate]

This question is a little bit stupid and silly. As I am chemist, I don't remember electricity physics very good. As I remember it shouldn't harm anything, but I need to be sure. LEDs will be ...
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1answer
50 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 ...
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5answers
99 views

Parallel Resistor Calculation — Higher Equivalent Resistance

\$R_1\$ and \$R_2\$ are in parallel. What should be the value of \$R_2\$ if \$R_1 = 100\Omega\$ and their equivalent resistance is \$1\text{k}\Omega\$?
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2answers
76 views

0402 versus 0201 resistor footprints

I am writing a manufacturing specification for our contract manufacturing. So far, the smallest component on our PCB is a 0402 resistor, however, I would like to specify a process that will be ...
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1answer
34 views

Calculate absolute values for resistor bridge to use with op amp lm358

I'm trying to make a simple thermostat using a thermistor and an Op Amp. The relevant part of my circuit diagram is shown below. simulate this circuit – Schematic created using CircuitLab ...
2
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1answer
25 views

semiconductor resistor vs resistor in SPICE modeling Altium

I'm doing some SPICE modeling using altium and would like to apply the temperature coefficients of the passive components for a more accurate simulation. However, as far as I know, in altium the ...
0
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1answer
39 views

How a P-Channel Mosfet works with a pull-up resistor

I have been desperately trying for days to troubleshoot this h-bridge I build so I'm trying to completely understand it first. What I don't understand is how R1 and ...
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2answers
336 views

Quick question about aux cable DIY

I've been planning to make an aux cable for my BMW 3-series, because the original costs 80€... So I've read a couple of DIY and I've found this So I've ordered the cable, capacitors, and the ...
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1answer
35 views

MIKROE-55 - LCD Datasheet [duplicate]

I'm a bit confused by the datasheet of a LCD (MIKROE-55). It says supply voltage is 3.5V (TYP), which results in as Supply current of 16mA. At first I understood this as: "connect K to GND and A to ...
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0answers
39 views

Single Transistor DC TO AC Circut

I have a question that may be rather difficult to ask and format however I will try. Now I am very new to electronics in general but in my spare time I play around with them a little bit. I have ...
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1answer
185 views

How many ohms do you need before you need a resistor?

Okay, I'm rather a bit confused here now. I am trying my first real circuits, for some LED lighting. I tried making a little circuit last night, matching two LEDs in parallel on 4.5v of battery. ...
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3answers
113 views

Unusual resistor symbol: resitor with Z overlaid

I found this symbol in a vendor circuit diagram. What does it mean? It looks like they are trying to convey some sort of limiting. It's a resistor symbol with a line over the top that has both the ...
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0answers
45 views

Powering up LEDs directly (without series resistor) with correct voltage [duplicate]

I am definitely not an expert in electronics, but as far as my understanding goes, one needs to put a resistor in series with an LED because in general the voltage supplied from the source could be ...
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3answers
483 views

what is the meaning of NOP in the schematic diagram?

what is the meaning of NOP in the schematic diagam?
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0answers
40 views

algebraic addition and subtraction within RC and RL

Why isn't it possible to algebraic add the potential drop of R and L within a serial circuit using alternate current? And why is ...
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1answer
89 views

What SMDs are these? [closed]

Just a quick question: Does anyone know what SMD are these? Thanks
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1answer
53 views

A question on precise resistor measurement for current loops

For a current outputting device I’m using a data acquisition board which can only measure voltages. To translate the currents to voltages I use similar to the following shunt resistor: ...
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2answers
165 views

Resistor circuit problem

I am having trouble with a circuit: simulate this circuit – Schematic created using CircuitLab I must calculate the voltage across R1.My answer is to first compute the current running ...
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5answers
908 views

Drop Voltage using Resistor: is it practical?

I should probably say that this a basic question, I don't know much about this stuff, please don't be too hard on me. Ok so I kind of thought it would be fun if I could light up 12V halogen lamps ...
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1answer
24 views

using TSOP4838 in anti-collision line follower

i want to use IR sensors with emitter part ( IR led ) - calibrated with an IC timer to give 38KHZ IR signal - mounted side by side - not face to face like the counter module - to the receiver part ( ...
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1answer
96 views

Need help in building a simple circuit using transistor

I am new to EE. I am trying to figure out a circuit. I need to make use of resistors,a BC547 and a LED. I am using a 9V power supply. Can you recommend a circuit schematic that uses only the ...
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1answer
82 views

How to analyze this circuit with resistors and capacitors?

I have to find out the value of \$V_{o}\$ and \$V_{c}\$ initially and finally of the this circuit when \$S_{1}\$ and \$S_{2}\$ switches are simultaneously closed. Edit: \$V_{c}\$ is across the ...
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1answer
74 views

What resistance/ load do battery testers (AA or AAA) use in Ohms please

Trying to find out what size resistors (Ohms) a AA or AAA battery tester would use? Have tried searching but unable to find an answer I meant testing alkaline and ni-mh 1.5volt and 1.2 volt batteries ...
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2answers
38 views

How to find the equivalent resistance for YY parallel connection

I am trying to find how to break apart a Y-Y connection to find the equivalent resistance. I understand how to find the equivalent resistance for 2 Y circuits in series, but not parallel. I ...
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2answers
85 views

Is there a best practice for resistor placement?

Resistors are color-coded by digit, multiplier, then tolerance, but the book I'm reading (comes with the Arduino starter kit) shows its breadboard diagrams with all the resistor tolerance bands ...
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1answer
60 views

Voltage measurement

With the 100ohm resistor sitting between my 12V power supply and my device it doesn't spin (it's a hard disk). I also tried to measure the voltage drop with a multimeter to no avail. It always shows ...
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2answers
165 views

Does the Y-Δ transform suffice for every resistor network?

Suppose I have a (finite of course!) network of resistors only. Is it always possible to calculate the equivalent resistance between any two points using only parallel, series, Y-Δ and Δ-Y (wye-delta ...
2
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4answers
78 views

Moving two elements from series to parallel

I got a small pizza oven with two elements (top and bottom), they are rated 115V 600W and they are connected in series, as we have 230V in Europe. Everything works fine, but I would like to control ...
3
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1answer
180 views

Achieving (near) exact voltage divider ratio

Often, I'll have a need to create a voltage divider that has a specific resistance ratio, to obtain whatever voltage I need on the output. For example, for a specific project I'm working on (creating ...
0
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3answers
95 views

Will connecting two batteries in parallel increase current drawn in simple led circuit?

I have a resistor diode circuit that I'm powering with a 9V battery. The circuit diagram below is a simplified version of it. The real one has 4 LEDs, 8 resistors. I want to deliver 30mA to the ...
2
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2answers
137 views

How to adjust linear voltage regulator equivalent?

I'm attempting to build a linear voltage supply. (I'm not touching the mains yet.) My first thought was to use an adjustable linear voltage regulator. Unfortunately, I found that linear voltage ...
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1answer
102 views

Led driver circuit 3.3v & 5v

Not long time ago, as i couldn't find a proper Mosfet to drive a high wattage led strip ( 5050,5630), i asked how to create a circuit that allows me to turn on properly the mosfets i already own. ...
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2answers
32 views

Circuit with switch - express the current for different times

Consider the circuit below consisting out of a capacitor C and two identical resistors R. For \$t<0\$ the switch is open and the capacitor is uncharged. At \$t=0\$ switch is shut and the circuit ...
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1answer
41 views

capacitor and resistor combination

I'm currently working on some simple circuits to learn about circuitry, and being a Physics major I have a pretty good grasp of the mathematics and concepts, but I'm a little confused about ...
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2answers
89 views

Using multiple current sense resistors in parallel to handle a high current measurement with cheaper resistors

I am measuring the current going to a motor using current sense resistors; however, in order to get a resistor that can handle the proper power, the price goes up way too much. My question is, can I ...
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3answers
406 views

Current flow through resistor and insufficient source

In a simple circuit consists of a source and resistor, according to Ohm's law, if 10V is applied to a 10 ohm resistor, the current flow through the circuit will be 1A. But what if the source in this ...
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1answer
60 views

What should be the size/package of Bob Smith Termination resistor?

We have run into a layout issue where the size/package of the 75R resistor used for Bob Smith termination on unused Ethernet pins is in question. The current package of this resistor is 1206 and we ...
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2answers
112 views

Resistor network explanation and calculations

First question - What is this resistor network doing? Answered that it's linearizing the thermistor but this isn't what I was looking for. I'm looking for an explanation that describes the ...
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1answer
36 views

Determine supply voltage for led from current limiting resistor

Everyone knows how to calculate the resistance of a current limiting resistor for a LED but is it possible to go the other way? (aka determine the supply voltage from the resistor's value) I ask ...
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2answers
59 views

Load Resistor for high amp low voltage testing

I want to simulate a signal of 15V / 30A through a device. I will use it to ensure that a series of prototypes are capable of switching at this current. $$ P = 15 \times 30 = 450W $$ $$ R = ...
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2answers
52 views

Resistor values for a passive audio mixer?

I'm trying to come up with a schematic for building a passive audio mixer for an aviation headset, but I'm having some questions about resistor values. Figuring out the general circuit is easy ...
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2answers
115 views

Is resistor on LED's necessary after voltage drop?

Let's say we have perfect 5V DC 0.1A power supply. Obviously for one LED we would need a resistor (I'm well aware of Ohm's law), BUT what if we connect bunch of LED's in series. And the current drain ...
0
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1answer
58 views

Driving MOSFET with 555 timer [duplicate]

I am building a plasma speaker using a 555 timer to generate the audio tone. I am driving a mosfet with the output of the 555 timer, which in turn powers a flyback transformer to generate a plasma ...
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4answers
170 views

How to test analog component before mounting?

I have been in a small factory today, they produced 4 kind of PCBs that all are simple analog boards, each month they produce 1000 of them. The problem is that till now, after mounting them almost 10% ...
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1answer
104 views

How do I amplify an input signal to match the peak of another signal

I would like to build building a Voltage Controlled Oscillator (VCO) for audio applications beginning with a relaxation oscillator build from op amps. Adding a potentiometer to the feedback loop ...