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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40 views

Complex power for RL and RC [on hold]

Is this true? Or is this true? Ø and Q are from this equation: When current is lagging the voltage, is this leading or lagging power?
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1answer
50 views

Safe way to wire CMOS ICs together

I have a question about the safety (to the ICs) of wiring the output of one IC directly to the input of another IC. simulate this circuit – Schematic created using CircuitLab For ...
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1answer
48 views

Resistors used in LM386 amplifier

I have found a circuit to bass bump headphone amplifier. In the parts list most of the resistors are 1/8 W, but I have only found 1/4W resistors. Will this effect the functioning of the amplifier? ...
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2answers
62 views

Fast thermal ramp up/ power efficiency [closed]

I want to build a controlled temperature well in an alumminum block, and right now I am in doub as to what heating method choose. I am mostly torn between a high power resistor such as this or ...
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3answers
84 views

Shunt Resistor on output of Voltage Regulator? [closed]

I was looking through a popular circuit on Sparkfun and trying to lower the power consumption of the device. I found that the outputs of their regulators are shunted to ground with a 300-ohm resistor. ...
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3answers
93 views

Inverse Laplace Transform of RLC Circuit

The voltage across the power source equals the summed voltage across the resistor, capacitor, and inductor at any time (t). This is shown in the equation below: ...
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1answer
24 views

Special Source Transformations

I'm not sure if this was asked already, but I could not find it when I searched. We're learning about source transformations, and while reading my textbook I came across this: and in the following ...
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1answer
87 views

BJT base resistor

I read this post: Which resistor for NPN transistor base? But I still cannot understand the base resistor calculation. I need the transistor to be a switch to 5V 200mA relay. The base will get its ...
3
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4answers
252 views

replace fan with resistor

I have always had a huge fascination with electronics, but never the time to devote to learning it beyond a couple of quick tutorials here and there (and the basics you learn in school). So, sorry if ...
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3answers
57 views

Load Resistor across Crystal

What is the purpose of using a 1M Ohm resistor across crystal pins? Please refer to the image for clarity. The crystal serves as the clock source for an USB Hub device(LAN9512). There is nothing ...
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7answers
4k views

How do you arrange six 6-ohm resistors to have a total resistance of 6-ohm?

Is there a mathematical way to know the answer? (or you can do it only by trial and error) Could you prove that it is possible or impossible mathematically?
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1answer
94 views

What is this resistor? [closed]

I am trying to find the value of a blown resistor so that I may replace it. Its from a Circulation Booster V3 circuit board. The marking on the board where the resistor lives is marked L1 It is green ...
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2answers
94 views

How to supply power to a 12V solenoid from China, getting hot

I bought this solenoid from ebay and was wondering how to power it. It says 12 volts as you can also see from the picture, but I tested it with putting a 9V battery straight to its terminals for a ...
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1answer
40 views

Impulse Response of a series RC filter where the output voltage is taken across the Capacitor

I am finding it difficult to understand the steps to derive the impulse response of a series RC filter where the output voltage is taken across the capacitor, the equation to derive is: h(t)= (1/RC) ...
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1answer
122 views

How can I limit the current in a 12v car battery to be safe for my 25a motor driver?

I have a 25amp Sabertooth Motor controller that can be powered by my 12v car battery. I have big 24v wheelchair motors attached to the motor controller. I do not know how much current that the motors ...
0
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3answers
59 views

Inverting Amplifier Not Giving Gain of -2.2

A LM358N op amp is used with R_f = 220k and R_i = 100k, which should give a gain of -2.2 in ...
4
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3answers
317 views

Transistor and Resistors [duplicate]

What is the function of the two resistors arranged in parallel with the transistor? Do they also limit the current to the transistor? The full circuit is this:
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3answers
102 views

Voltage of Voltage Regulator changes when a Potential Divider is added

A Keithley 2400 Source meter is used to provide +7V. Using Fluke 179 Multimeter, the potential across the source meter leads is 7.00V. The source meter is then ...
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5answers
237 views

How to mirror resistor? (use same variable resistance for multiple op-amp gains)

I want to create parallel op-amp circuits/channels and use the value from a single potentiometer to adjust the gains of each uniformly by making each op-amp see a 'copy' of the resistance to set the ...
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1answer
64 views

What is the current before arriving a resistor and after leaving it in the wire?

Suppose we have a very simple circuit, with just a resistor between a wire connected to a power source. What's the actual value of current travelling the wire before and after the resistor? Is it ...
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5answers
1k views

What reasons are there to avoid vertical through-hole resistors?

I'm working on a layout for a PCB and I need to include a handful of pull-up resistors. The board I'm working on will be a proof of concept, and it is likely I will only need one (and order two). That ...
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6answers
822 views

What is the function of the resistor in the below circuit?

What is the function of the resistor R13 in this circuit?
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2answers
94 views

does this design look suitable for a 4-bit adder

I am working on a project that will include a basic 4-bit adder, I have designed a layout is Adobe Illustrator and would like people to check over it to see if it looks like it should work. I am very ...
2
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1answer
75 views

Reversing a Photoresistor

I'm a total newbie at this, but I have a photoresistor set up so that it controls the shorting on an audio circuit. When light is on, it shorts and cuts the sound. When it is dark, it closes and ...
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1answer
110 views

What standard governs the dimensions of SMT chip resistors and capacitors?

I am aware of the JEDEC registered outlines, which define the standard mechanical dimensions and tolerances for a wide variety of solid-state packages. However, these standards do not appear to cover ...
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0answers
41 views

How to measure force on line

Trying to figure out how to measure force on a string which is being pulled. I can't attach it to anything and the force is great enough to cause it to unravel from a spool. Was thinking of ...
3
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2answers
440 views

Control 5V DC motor with Arduino

I'm trying to build a circuit to control a 5V DC motor with Arduino. My issue is that I can't understand the resistance value within this scheme: Which resistor should I use in order to make work ...
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3answers
71 views

Resistance calculation [duplicate]

Are these resistors in parallel? A question is asked to find the equivalent resistance between X1 and X2; to my knowledge, these resistors are like parallel connections. But the choices are given ...
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3answers
75 views

Linear potentiometer for suspension travel

I am working on a project for university measuring the extension of a cars suspension. I have a potentiometer available to me, but have a few questions regarding how to use it. I understand that it ...
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2answers
56 views

Power Resistor TO-263 in Layout (Eagle) [duplicate]

I am using this Power Resistor here and I am trying to put it in my layout. The Problem is I can't find any .lib (TO-263 or D2PK) file in Eagle or at least a similar package. Any Help?
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1answer
98 views

How do you size pull-up/down resistors? [duplicate]

The attached photo is pulled from a Piccolo DSP reference design from TI. They use 57.6k pull-up resistors and 2.2k pull-down resistors to allow configuration of boot pins at startup. I've seen all ...
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2answers
94 views

How to use ordinary voltage regulator from a 40amp source?

My power source is 12v 40amp(car battery). My project needs 12v but only 500 or 1000ma max. My 12v voltage regulator (NTE960) explodes with 40amps, so I must reduce the current (too much current for ...
2
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4answers
152 views

Resistor technologies that guarantee failure mode of OPEN and not short--need docs to prove

From chats with several resistor manufacturers, it seems that there's a consensus that certain resistor technologies at high impedance ~120Kohm or more will always open and never short. Does anyone ...
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2answers
52 views

Grounding a conducting object

Is it possible to trap some electricity in the object even though the object is grounded? For example if we ground a conducting sphere over a resistor, will all electricity leave the sphere once it's ...
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1answer
56 views

Resistors calibration about tolerance [closed]

Would it ever be possible to find a value of resistor that is outside the stated tolerance? kindly help, practically is it possible?
2
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3answers
231 views

What resistors to use to read several buttons with a single analog pin

EDIT: Thanks, all of you helped a lot! Ricardo summed everything up nicely so I'll mark his answer as the best, but all of the answers helped me understand. Thanks again :). I have an Arduino Uno R3 ...
0
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0answers
64 views

How to draw a circuit with resistors for 3 nodes?

I am tasked to draw a circuit of a black box that had 3 plugs, and I was able to build the circuit by measuring resistance values across each set of plugs. The plugs are A, B, C, so I had resistance ...
0
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1answer
50 views

3296 trimpot adjustment

I've got a 3296 trimpot like this one: http://pdf1.alldatasheet.com/datasheet-pdf/view/78495/BOURNS/3296.html I don't know whether clockwise or counter-clockwise increases or decreases the ...
0
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2answers
132 views

Reverse voltage circuit protection using an N-channel MOSFET

I am currently working on a drive for a DC motor and I want to add a reverse voltage protection on my circuit so it doesn't fry in the case of an inverted power supply. I've read many tutorials on ...
1
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1answer
61 views

Thermal Johnson-Nyquist Noise Generator

I have no background in electrical engineering so please bear with me. I want to create a random number generator/displayer using a resistor. My idea is to wire a resistor to an amplifier of some ...
4
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2answers
302 views

Signal LED delay mini-circuit

In making a breakout board for an SMD Bluetooth module, I realized that simply wiring LEDs to your signal lines is insufficient for a decent visual indication, as signal duration is too short to be ...
3
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1answer
162 views

Identifying a resistor with implausible or impossible color bands

How can I find out the value of this burnt-out resistor from a power supply? I've tried a few online resistor calculators and every single of them gives different values ranging from 0.1 ohms to ...
1
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1answer
219 views

How to modify DS1307 RTC to use 3.3V for Raspberry Pi?

I bought DS1307 RTC but it is 5V so it can't be connected to the Pi. I know it can be modified to use 3.3V by removing 2 resistors. This sensor is different than the adafruit kit so I am not sure ...
6
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3answers
195 views

Is the error in a “5%” resistor consistent across measurements?

One of my projects involves a number of voltage dividers... but if I'm worried about precision (which I'm really not, but I want to understand how these things actually work) can I realistically use ...
1
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2answers
154 views

Permanently dimming an incandescent light bulb

I have purchased a nice light bulb with long visible wires/resistors and plugged it in, on the ceiling. It burns too bright without a dimmer and does not look as intended (also the lifespan ...
1
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1answer
86 views

Identify and replace a resistor [closed]

My APC UPS stopped working. I have had it for many years and it was serviced once by APC while in warranty and never opened again. Now since it is not in warranty anymore I opened it and saw two ...
0
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2answers
55 views

Creating a specific volt/current “test load”

Working on a complex power supply, but to test its limits I would like to create a set of test loads of specific voltage/current. There are several devices for creating a set load, but they seem to ...
2
votes
1answer
54 views

Possible uses of a MELF resistor?

I have been doing some net-surfing on Farnell's website and stumbled upon a section called MELF Surface Mount Resistors According to Wikipedia, this package family has a rather funnily ...
6
votes
3answers
94 views

How should I use rotary switches and resistor networks to uniquely relate each possible combination of switch settings to an analog voltage?

I'm designing a switched-mode power supply. I need to give my users the ability to set a voltage setpoint, with a range of approximately 200-800V, and at least 4V of resolution. This needs to be a ...
0
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2answers
52 views

Are there other uses for the value of RMS current besides heating computations?

For most purposes I've personally encountered, RMS current and voltage have been useful only for computing heat losses in a resistor. Do RMS current or voltage have other applications besides ...