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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8 votes
4 answers
10k views

Tolerance of voltage dividers with different values for R1 and R2

If I have two 1k resistors rated at 1% fed by a perfect 10V source then what is the otuput guaranteed to be? 5V ±1% or 5V ±2% or some other value? I can work out this case easily, assume that R1 is ...
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24 votes
3 answers
8k views

Zero ohm resistor tolerance?

This 0Ω resistor has a tolerance of ±1%. Well it would only be +1% at best because you can't have a negative resistance* but still 1% of zero is still zero? Shouldn't it be something like 0\$\...
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12 votes
3 answers
21k views

What do the colors of resistor bodies mean?

I don't mean the colored bands, but the colors of the bodies themselves. They come in brown, blue, green, etc. Is there a standard? For instance, epanorama says: But there are two resistor body ...
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5 votes
6 answers
5k views

Variable resistor

I'm starting with electronics and I don't have a lot of resistors. Every new project I try to do, I have to buy new resistors, but they take a long time to arrive. What's the solution? What variable ...
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5 votes
2 answers
3k views

Using Pullup and Pulldown Resistors

I've been researching pullup and pulldown resistors after seeing them used in many digital circuits and while I understand what their purpose is, I haven't found any resource on how to determine the ...
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  • 2,117
10 votes
6 answers
11k views

Inexpensive solid-state variable resistor

I have an analog audio project I'm playing around with designs for and it will need about 150 solid-state variable resistors. I plan to control these from a micro controller so a digitally controlled ...
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97 votes
29 answers
102k views

What's the best way to store and categorise resistors/capacitors/ICs/etc?

I did a big cleanup of my collection of parts today and I now have a big pile of parts on my desk (the majority of which is resistors). My previous method of finding the resistor value I wanted was to ...
2 votes
2 answers
401 views

Can I adjust varistor range?

I can connect many resistor in parallel or series to get a final resistance I want in case when I have no necessary nominal out of the box. I wonder is there such trick that will allow me to easily ...
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1 vote
1 answer
6k views

Thermistors' colour coding same as the resistors'?

WARNING: 30V was a mistake -- better to keep voltage down 12V as a beginner! I tested it over a very short time. Got the things hot over a long time with much less voltage -- apparently not enough ...
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5 votes
4 answers
18k views

At what current and voltage do typical resistors explode?

I don't have an explosion chamber, so I cannot test critical values. If you explode resistors with too high current-voltage combination, does it damage your equipment, such as multimeter and DC-...
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9 votes
7 answers
5k views

Best shunt resistor for power meter application?

Looking for a shunt resistor for measuring power usage and was wondering if anyone had any experience with these. It should be capable of handling 110V/20A in-home circuit. EDIT: Energy monitors ...
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9 votes
3 answers
989 views

Should I default to pull-up or pull-down resistor with tact switches?

I understand the basic use of a pull-up or pull-down resistor, including the specific case of using it with a tact switch. When both are an option I was wondering whether I should favor one over the ...
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7 votes
7 answers
36k views

What is the purpose of a bias resistor?

Could someone explain what "bias" is. And why do some devices need an external bias resistor?
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92 votes
11 answers
163k views

Is there a correct resistance value for I2C pull-up resistors?

The datasheet of the 24LC256 EEPROM states that: The SDA bus requires a pull-up resistor to VCC (typical 10 kΩ for 100 kHz, 2 kΩ for 400 kHz and 1 MHz). I thought that any resistor with a kΩ value ...
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27 votes
6 answers
23k views

How does an LM7805 voltage regulator work?

How do most voltage regulator ICs work? Are they the same as hooking up a variable resistor and a voltmeter and turning the knob until you get the desired voltage?
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10 votes
5 answers
8k views

Red Green Blue LED

Do you need to use different resistors against each of the colours on an RGB LED?
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8 votes
3 answers
7k views

Why the resistor in this op-amp circuit?

Here's a circuit diagram for a signal response test circuit from the spec sheet for a HA-5195 op amp and looks like a non-inverting amplifier circuit with a gain of 5, plus the 200Ω resistor between ...
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  • 505
25 votes
2 answers
17k views

6 Band Resistors, which way should the bands be read

I've just bought a bag of random resistors from Maplin, and can't work out which way round the six band ones should be read. For instance I have one which is either: Violet Orange Red Brown Brown ...
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