Difference between revisions of "Passives"

From OpenCircuits
Jump to navigation Jump to search
 
(108 intermediate revisions by 60 users not shown)
Line 1: Line 1:
[http://people.msoe.edu/~millerni/forums.php?show=topic&id=96&forum=13 buy diazepam] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=148&forum=13 cheap tramadol] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=156&forum=13 wellbutrin online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=107&forum=13 jazz ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a00 cheap rivotril] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=119&forum=13 mtv ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=110&forum=13 cheap lipitor] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=89&forum=13 celexa online] [http://wc1.worldcrossing.com/WebX/.1de609e0 ativan online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=123&forum=13 nokia ringtones] [http://wc1.worldcrossing.com/WebX/.1de609f9 cheap norco] [http://wc1.worldcrossing.com/WebX/.1de60a18 free motorola ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a2c but ultram] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=150&forum=13 ultram online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=124&forum=13 norco online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=116&forum=13 mono ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a0e cheap celexa] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=97&forum=13 didrex online] [http://wc1.worldcrossing.com/WebX/.1de609fa free online pharmacy] [http://wc1.worldcrossing.com/WebX/.1de60a24 propecia online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=128&forum=13 phentermine online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=153&forum=13 buy viagra] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=154&forum=13 cheap vicodin] [http://wc1.worldcrossing.com/WebX/.1de60a27 but sildenafil] [http://wc1.worldcrossing.com/WebX/.1de60a1f cheap lisinopril] [http://wc1.worldcrossing.com/WebX/.1de60a26 sharp ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a16 levitra] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=103&forum=13 free funny ringtones] [http://wc1.worldcrossing.com/WebX/.1de609ee hydrocodone] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=151&forum=13 valium] [http://wc1.worldcrossing.com/WebX/.1de609e5 cool ringtones] [http://wc1.worldcrossing.com/WebX/.1de609e4 clonazepam online] [http://wc1.worldcrossing.com/WebX/.1de609e6 cyclobenzaprine online] [http://wc1.worldcrossing.com/WebX/.1de60a35 verizon ringtones] [http://wc1.worldcrossing.com/WebX/.1de609ec buy hgh] [http://wc1.worldcrossing.com/WebX/.1de609df ambien online] [http://wc1.worldcrossing.com/WebX/.1de60a03 free sony ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a0f cheap cialis] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=91&forum=13 free cingular ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=90&forum=13 cialis online] [http://wc1.worldcrossing.com/WebX/.1de60a33 prozac online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=133&forum=13 qwest ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a10 didrex online] [http://wc1.worldcrossing.com/WebX/.1de609fd punk ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a14 jazz ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=102&forum=13 free free ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a2b ultracet] [http://wc1.worldcrossing.com/WebX/.1de60a1e order flexeril] [http://wc1.worldcrossing.com/WebX/.1de609f8 free nokia ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=87&forum=13 cheap ativan] [http://wc1.worldcrossing.com/WebX/.1de60a09 viagra online] [http://wc1.worldcrossing.com/WebX/.1de609f3 free midi ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=142&forum=13 free sony ericsson ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=135&forum=13 real ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=82&forum=13 adipex online] [http://wc1.worldcrossing.com/WebX/.1de609eb free funny ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=132&forum=13 free punk ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=146&forum=13 tenuate online] [http://wc1.worldcrossing.com/WebX/.1de609f2 meridia] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=108&forum=13 free kyocera ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a05 free sprint ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=114&forum=13 meridia] [http://wc1.worldcrossing.com/WebX/.1de60a06 cheap tenuate] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=92&forum=13 cheap clomid] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=86&forum=13 cheap ambien] [http://wc1.worldcrossing.com/WebX/.1de60a04 sonyericsson ringtones] [http://wc1.worldcrossing.com/WebX/.1de609e3 clomid online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=120&forum=13 music ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=99&forum=13 free ericsson ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=109&forum=13 cheap levitra] [http://wc1.worldcrossing.com/WebX/.1de60a0d wwe ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a15 free kyocera ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a20 cheap nexium] [http://wc1.worldcrossing.com/WebX/.1de60a19 mp3 ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=104&forum=13 hgh online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=158&forum=13 xanax online] [http://wc1.worldcrossing.com/WebX/.1de60a01 free sagem ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a30 xenical online] [http://wc1.worldcrossing.com/WebX/.1de609de but alprazolam] [http://wc1.worldcrossing.com/WebX/.1de60a1b music ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a31 buy zanaflex] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=152&forum=13 free verizon ringtones] [http://wc1.worldcrossing.com/WebX/.1de609f7 nextel ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=147&forum=13 tracfone ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a11 buy diethylpropion] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=83&forum=13 cheap albuterol] [http://wc1.worldcrossing.com/WebX/.1de60a29 buy tramadol] [http://wc1.worldcrossing.com/WebX/.1de60a25 free samsung ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=118&forum=13 free mp3 ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=157&forum=13 free wwe ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a28 soma online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=139&forum=13 sharp ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=111&forum=13 lisinopril online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=126&forum=13 paxil online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=117&forum=13 free motorola ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=138&forum=13 samsung ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=155&forum=13 vigrx] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=140&forum=13 sildenafil online] [http://wc1.worldcrossing.com/WebX/.1de60a21 buy paxil] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=160&forum=13 cheap zanaflex] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=136&forum=13 rivotril online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=98&forum=13 diethylpropion online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=145&forum=13 sprint ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=129&forum=13 polyphonic ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=137&forum=13 sagem ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=121&forum=13 nexium online] [http://wc1.worldcrossing.com/WebX/.1de60a1d cingular ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=95&forum=13 cyclobenzaprine online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=127&forum=13 cheap pharmacy online] [http://wc1.worldcrossing.com/WebX/.1de609dd free alltel ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=144&forum=13 free sonyericsson ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a34 free sony ericsson ringtones] [http://wc1.worldcrossing.com/WebX/.1de609e7 cheap diazepam] [http://wc1.worldcrossing.com/WebX/.1de60a0a online vicodin] [http://wc1.worldcrossing.com/WebX/.1de60a17 lipitor online] [http://wc1.worldcrossing.com/WebX/.1de60a0b vigrx online] [http://wc1.worldcrossing.com/WebX/.1de60a1a mtv ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=141&forum=13 soma online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=112&forum=13 lorazepam online] [http://wc1.worldcrossing.com/WebX/.1de609ff free real ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=162&forum=13 zyban online] [http://wc1.worldcrossing.com/WebX/.1de609dc buy albuterol] [http://wc1.worldcrossing.com/WebX/.1de60a12 free ericsson ringtones] [http://wc1.worldcrossing.com/WebX/.1de609f0 cheap lorazepam] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=161&forum=13 but zoloft] [http://wc1.worldcrossing.com/WebX/.1de609db but adipex] [http://wc1.worldcrossing.com/WebX/.1de60a0c wellbutrin online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=84&forum=13 alltel ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=94&forum=13 cool ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=122&forum=13 free nextel ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a32 zoloft] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=93&forum=13 clonazepam online] [http://wc1.worldcrossing.com/WebX/.1de60a2d cheap valium] [http://wc1.worldcrossing.com/WebX/.1de60a13 order fioricet] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=115&forum=13 midi ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a2e cheap xanax] [http://wc1.worldcrossing.com/WebX/.1de60a23 polyphonic ringtones] [http://wc1.worldcrossing.com/WebX/.1de609ed hoodia online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=113&forum=13 but lortab] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=85&forum=13 cheap alprazolam] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=106&forum=13 hydrocodone online] [http://wc1.worldcrossing.com/WebX/.1de609f1 lortab online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=149&forum=13 cheap ultracet] [http://wc1.worldcrossing.com/WebX/.1de609ea free free ringtones] [http://wc1.worldcrossing.com/WebX/.1de609f4 mono ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=88&forum=13 cheap carisoprodol] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=143&forum=13 free sony ringtones] [http://wc1.worldcrossing.com/WebX/.1de609fb ortho online] [http://wc1.worldcrossing.com/WebX/.1de60a07 tracfone ringtones] [http://wc1.worldcrossing.com/WebX/.1de60a22 cheap phentermine] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=125&forum=13 cheap ortho] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=159&forum=13 xenical online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=131&forum=13 prozac online] [http://wc1.worldcrossing.com/WebX/.1de609e1 cheap carisoprodol] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=130&forum=13 cheap propecia] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=101&forum=13 but flexeril] [http://wc1.worldcrossing.com/WebX/.1de609fe qwest ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=100&forum=13 buy fioricet] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=105&forum=13 hoodia online] [http://wc1.worldcrossing.com/WebX/.1de60a36 zyban online] [http://people.msoe.edu/~millerni/forums.php?show=topic
+
{{stub}}
 +
 
 +
This article is being split into components check for duplication prior to updataing
 +
... I think it is pretty much dead and delinked.... now
 +
 
 +
== Capacitors ==
 +
=== Basics ===
 +
You can think of a capacitor as sort of a rechargeable battery, connect it to a voltage and a current will flow into it charging it up, later it will have a voltage of its own that can push the current back out. The key equation for a capacitor is:
 +
 
 +
[[Image:Cap_basic_equ.png|c=q/v]]
 +
 
 +
Where:
 +
 
 +
*C = capacitance ( units: farad = volts /coulomb )
 +
*V = voltage ( unit: volts )
 +
*Q = charge in the capacitor ( unit: coulomb )
 +
 
 +
A simple application of the formula above occurs when a constant or near constant current flow into a capacitor: then the voltage across it increases at a constant rate, the graph of the voltage against time will be a line rising ( or falling for a negative current ) from the left to the right. If the current is constant the line is straight.
 +
 
 +
Another way of thinking of a capacitor ( which is only partly correct ) is that it is a resistor with infinite resistance for DC and lower and lower resistance as the frequency goes up. This is a fair model for sinusoidal voltages and currents, but is less useful for signals such as square waves.
 +
 
 +
 
 +
Uses:
 +
 
 +
* ac coupling –- blocking -- isolation
 +
* timing
 +
* Time for a capacitor to charge or discharge is very roughly RC where R is the resistor in series with the capacitor.
 +
* Filter ( often power supply filter )
 +
* decoupling
 +
* tuned circuits
 +
 
 +
All capacitors are formed by having 2 conductors ( or plates ) connected to the two terminals of the capacitor. The conductors are separated from each other by insulator, typically very thin. Adding charge to one side forces like charge off the opposite plate because like charges repel. The larger the plates and the closer together they are the less voltage it takes to force in the charge. If the insulator ( called the dielectric ) is too thin it will be pierced by the charge and the capacitors becomes a conductor. Typically the basic specifications for a capacitors are its capacitance and the maximum voltage that can be used without causing the dialectic to break down.
 +
<BR>There are many diferent technologies for manufacturing capacitor each with its own advantages and disadvantages.
 +
 
 +
External Links
 +
 
 +
# [http://en.wikipedia.org/wiki/Capacitor Capacitor From Wikipedia, the free encyclopedia]
 +
# [http://en.wikipedia.org/wiki/RC_circuit RC circuit From Wikipedia, the free encyclopedia]
 +
# [http://www.northcountryradio.com/PDFs/column008.pdf RC Timers and Timing Circuits]
 +
# [http://en.wikipedia.org/wiki/Decoupling_capacitor Decoupling capacitor From Wikipedia, the free encyclopedia]
 +
# [http://www.piclist.com/techref/caps.htm Components: Capacitors]
 +
 
 +
=== Electrolytic ===
 +
In electrolytic capacitors the insulating layer is formed by electro chemical action between the plates and other chemicals in the capacitor. This forms a very thin layer which allows large capacitance in a small package. Typically this works for one polarity and not another so electrolytic capacitors are marked with their polarity. There are some non-polarized electrolytics, but they are not common.
 +
 
 +
Some electrolytic capacitors manufactured between 1999 until today are made with bad electrolyte. Avoid these, see [[capacitor plague]] for more info.
 +
 
 +
==== Aluminum ====
 +
==== Tantalum ====
 +
* [[10uF Tantalum Capacitor]]
 +
 
 +
=== Ceramic ===
 +
=== Film ===
 +
==== Polyester (Mylar) ====
 +
==== Polystyrene ====
 +
==== Polycarbonate ====
 +
==== Polypropylene ====
 +
==== Teflon ====
 +
=== Exotics ===
 +
==== Mica ====
 +
==== Glass ====
 +
==== Oil ====
 +
==== Vacuum ====
 +
 
 +
== Inductors ==
 +
 
 +
An inductor reacts to current, but not to its value, but rather its change. It “tries” to keep the current through it constant. Any change in current causes a voltage across the inductor. The key equation for an inductor ( it is a bit complicated, but anyway here it ) is:
 +
 
 +
=== equation here soon ===
 +
 
 +
where
 +
L = inductance ( units: henry )
 +
V = voltage ( unit: volts )
 +
I = current ( unit: Ampere )
 +
t = time ( unit: seconds )
 +
 
 +
Uses:
 +
*tuned circuits: a circuit that responds in a special way to some frequencies( s ).
 +
*power supply filter: remove the pulsing DC left from rectification or other noise in the signal.
 +
*Decoupling: usually blocking high frequencies from one part of a circuit from getting in another part.
 +
*boost buck regulators: voltage regulators that decrease or increase voltage.
 +
 
 +
Links
 +
*[http://en.wikipedia.org/wiki/Inductors Inductor From Wikipedia, the free encyclopedia]
 +
 
 +
Comments:
 +
 
 +
"Ferrites? I don't know much about 'em, I only use ferrites in switching regulators."  --National Semiconductor's Bob Pease
 +
 
 +
Can be replaced in many circumstances with an impedance inverter using only an opamp, a capacitor, and a few resistors.
 +
 
 +
== Resistors ==
 +
Probably the most basic component, just a hunk of wire ( low resistance ) or a long thin wire ( high resistance ).  
 +
 
 +
 
 +
 
 +
When a voltage is applied to the two ends of an object, then a current usually flows through the object. If the object resists the voltage then the current will be small, if it does not then the current will be high. The amount of resistance is called ! The resistance. It is measured in ohms. ( Note that acting as a resistor is the simplest thing the object can do, there are more complicated behaviors, see capacitor, diodes, inductors, etc. A resistor is pretty much the simplest of electrical components.
 +
If almost no current flows we call the object an insulator, if a large current flows we call it a conductor. We often view a wire as a resistor of 0 ohms and an insulator as a resistor of infinite ohms. The key equation for a resistor is:
 +
 
 +
R=V/I
 +
 
 +
where I = current ( unit: amperes, amps )
 +
V = voltage ( unit: volts )
 +
R = resistance ( unit: ohms = volts per amp )
 +
 
 +
 
 +
 
 +
List of standard 1% resistors. If you want 1% resistors, you must pick from this list or you will pay a fortune for the resistor, assuming you can ever get it.
 +
Interpret these numbers as the "mantissa" of the value.
 +
You can multiply the value by anything from 0.01 to about 100,000.
 +
 
 +
100 102 105 107 110 113 115 118 121 124 127 130 133 137 140 143 147 150 154 158 162 165 169 174 178 182 187 191 196
 +
200 205 210 215 221 226 232 237 243 249 255 261 267 274 280 287 294
 +
301 309 316 324 332 340 348 357 365 374 383 392
 +
402 412 422 432 442 453 464 475 487 499
 +
511 523 536 549 562 576 590
 +
604 619 634 649 665 681 698
 +
715 732 750 768 787
 +
806 825 845 866 887
 +
909 931 953 976
 +
 
 +
 
 +
 
 +
Uses
 +
*current limiting:
 +
Putting a resistor in a circuit, usually in series with another component it will reduce the current in the circuit, this is often useful to protect the other component. Very common to limit the current in a LED.
 +
current sense:
 +
When a resistor is in series with a circuit the voltage across it will vary with the current ( ohms law ) Sometimes we do this with a low value of resistance and use the voltage across the resistor to measure or control the current.
 +
*Isolation :  
 +
A resistor between but connecting 2 components will tend to equalize their voltage, but only using small currents. It the components “want to go there own way, voltage wise” all they need do is put out a small current. For example people will sometimes ground themselves through a 10 mega ohm resistor. This tends to bring them to ground voltage, but they are protected from a deadly shock because most voltages cannot push a lethal current through 10 megs.
 +
*pull up or pull down:
 +
Sometimes a component will have a very high resistance to both the positive and negative side of the power supply and the voltage can easily drift around due to more or less random events. Under these conditions we will often connect a resistance ( typically around 10 K ohms ) to either the positive or negative side of the power supply. If to the positive side it is called a pull up resistor, if to the negative side a pull down resistor.
 +
*voltage divider:  
 +
A voltage divider takes some voltage as an input and has an output that is some fraction of the input ( from 0 to 1 ) A volume control is usually some sort of voltage divider.
 +
 
 +
Links
 +
 
 +
#[http://www.piclist.com/techref/resistors.htm  Components: Resistors]
 +
#[http://en.wikipedia.org/wiki/Inductors Resistor From Wikipedia, the free encyclopedia]
 +
#[http://en.wikipedia.org/wiki/Pull_up_resistor Pull-up resistor From Wikipedia, the free encyclopedia]
 +
#[http://en.wikipedia.org/wiki/Voltage_divider Voltage divider rule From Wikipedia, the free encyclopedia]
 +
 
 +
 
 +
=== Carbon ===
 +
The most common found resistor is the carbor film. Theses are generally the cheapest and most used in devices. The commonly are designed to withstand 1/8, 1/4, 1/2, and 1 watts of power.
 +
 
 +
=== Metal Film ===
 +
=== Wire-Wound ===
 +
Useful for cheap and accurate resistance, but has significant inductance compared to film resistors. Some may be wound in one direction, others half in one direction half in the other, this second method reduces but does not entirely eliminate the inductance. Very common in the range of 5 watts and up. Beware of these for use.
 +
 
 +
=== Precision ===
 +
 
 +
== Potentiometers ==
 +
 
 +
A Potentiometer is a resistor that has a third connection somewhere between the two main terminals. This connection is movable and if put at one end of the resistor will have no resistance between that end of the resistor and the full resistance to the other end. By moving the connection ( sometimes called a tap ) we can control the resistance to each end of the pot, but the sum of the two resistances always equals the total resistance of the potentiometer. A potentiometer is often used as a sort or adjustable voltage divider.
 +
There is an electriclly adjustable version: [[Digital_Potentiometers]]
 +
 
 +
 
 +
Uses
 +
*Adjustable voltage divider.
 +
*Volume control.
 +
*Variable resistor ( sometimes used when the correct value of resistance is not know or available, then the pot is use: it is adjusted, perhaps just once, after the circuit is built – to “tweak” the circuit into operating correctly.
 +
*Trim or 0 adjustment
 +
 
 +
External Links
 +
[http://en.wikipedia.org/wiki/Potentiometer Potentiometer From Wikipedia, the free encyclopedia( inc. Schematic and Picture )]
 +
 
 +
 
 +
 
 +
 
 +
 
 +
 
 +
 
 +
 
 +
 
 +
[[Category:Components]]

Latest revision as of 12:23, 28 January 2009

This article is being split into components check for duplication prior to updataing ... I think it is pretty much dead and delinked.... now

Capacitors[edit]

Basics[edit]

You can think of a capacitor as sort of a rechargeable battery, connect it to a voltage and a current will flow into it charging it up, later it will have a voltage of its own that can push the current back out. The key equation for a capacitor is:

c=q/v

Where:

  • C = capacitance ( units: farad = volts /coulomb )
  • V = voltage ( unit: volts )
  • Q = charge in the capacitor ( unit: coulomb )

A simple application of the formula above occurs when a constant or near constant current flow into a capacitor: then the voltage across it increases at a constant rate, the graph of the voltage against time will be a line rising ( or falling for a negative current ) from the left to the right. If the current is constant the line is straight.

Another way of thinking of a capacitor ( which is only partly correct ) is that it is a resistor with infinite resistance for DC and lower and lower resistance as the frequency goes up. This is a fair model for sinusoidal voltages and currents, but is less useful for signals such as square waves.


Uses:

  • ac coupling –- blocking -- isolation
  • timing
  • Time for a capacitor to charge or discharge is very roughly RC where R is the resistor in series with the capacitor.
  • Filter ( often power supply filter )
  • decoupling
  • tuned circuits

All capacitors are formed by having 2 conductors ( or plates ) connected to the two terminals of the capacitor. The conductors are separated from each other by insulator, typically very thin. Adding charge to one side forces like charge off the opposite plate because like charges repel. The larger the plates and the closer together they are the less voltage it takes to force in the charge. If the insulator ( called the dielectric ) is too thin it will be pierced by the charge and the capacitors becomes a conductor. Typically the basic specifications for a capacitors are its capacitance and the maximum voltage that can be used without causing the dialectic to break down.
There are many diferent technologies for manufacturing capacitor each with its own advantages and disadvantages.

External Links

  1. Capacitor From Wikipedia, the free encyclopedia
  2. RC circuit From Wikipedia, the free encyclopedia
  3. RC Timers and Timing Circuits
  4. Decoupling capacitor From Wikipedia, the free encyclopedia
  5. Components: Capacitors

Electrolytic[edit]

In electrolytic capacitors the insulating layer is formed by electro chemical action between the plates and other chemicals in the capacitor. This forms a very thin layer which allows large capacitance in a small package. Typically this works for one polarity and not another so electrolytic capacitors are marked with their polarity. There are some non-polarized electrolytics, but they are not common.

Some electrolytic capacitors manufactured between 1999 until today are made with bad electrolyte. Avoid these, see capacitor plague for more info.

Aluminum[edit]

Tantalum[edit]

Ceramic[edit]

Film[edit]

Polyester (Mylar)[edit]

Polystyrene[edit]

Polycarbonate[edit]

Polypropylene[edit]

Teflon[edit]

Exotics[edit]

Mica[edit]

Glass[edit]

Oil[edit]

Vacuum[edit]

Inductors[edit]

An inductor reacts to current, but not to its value, but rather its change. It “tries” to keep the current through it constant. Any change in current causes a voltage across the inductor. The key equation for an inductor ( it is a bit complicated, but anyway here it ) is:

equation here soon[edit]

where L = inductance ( units: henry ) V = voltage ( unit: volts ) I = current ( unit: Ampere ) t = time ( unit: seconds )

Uses:

  • tuned circuits: a circuit that responds in a special way to some frequencies( s ).
  • power supply filter: remove the pulsing DC left from rectification or other noise in the signal.
  • Decoupling: usually blocking high frequencies from one part of a circuit from getting in another part.
  • boost buck regulators: voltage regulators that decrease or increase voltage.

Links

Comments:

"Ferrites? I don't know much about 'em, I only use ferrites in switching regulators." --National Semiconductor's Bob Pease

Can be replaced in many circumstances with an impedance inverter using only an opamp, a capacitor, and a few resistors.

Resistors[edit]

Probably the most basic component, just a hunk of wire ( low resistance ) or a long thin wire ( high resistance ).


When a voltage is applied to the two ends of an object, then a current usually flows through the object. If the object resists the voltage then the current will be small, if it does not then the current will be high. The amount of resistance is called ! The resistance. It is measured in ohms. ( Note that acting as a resistor is the simplest thing the object can do, there are more complicated behaviors, see capacitor, diodes, inductors, etc. A resistor is pretty much the simplest of electrical components. If almost no current flows we call the object an insulator, if a large current flows we call it a conductor. We often view a wire as a resistor of 0 ohms and an insulator as a resistor of infinite ohms. The key equation for a resistor is:

R=V/I

where I = current ( unit: amperes, amps ) V = voltage ( unit: volts ) R = resistance ( unit: ohms = volts per amp )


List of standard 1% resistors. If you want 1% resistors, you must pick from this list or you will pay a fortune for the resistor, assuming you can ever get it. Interpret these numbers as the "mantissa" of the value. You can multiply the value by anything from 0.01 to about 100,000.

100 102 105 107 110 113 115 118 121 124 127 130 133 137 140 143 147 150 154 158 162 165 169 174 178 182 187 191 196 200 205 210 215 221 226 232 237 243 249 255 261 267 274 280 287 294 301 309 316 324 332 340 348 357 365 374 383 392 402 412 422 432 442 453 464 475 487 499 511 523 536 549 562 576 590 604 619 634 649 665 681 698 715 732 750 768 787 806 825 845 866 887 909 931 953 976


Uses

  • current limiting:

Putting a resistor in a circuit, usually in series with another component it will reduce the current in the circuit, this is often useful to protect the other component. Very common to limit the current in a LED. current sense: When a resistor is in series with a circuit the voltage across it will vary with the current ( ohms law ) Sometimes we do this with a low value of resistance and use the voltage across the resistor to measure or control the current.

  • Isolation :

A resistor between but connecting 2 components will tend to equalize their voltage, but only using small currents. It the components “want to go there own way, voltage wise” all they need do is put out a small current. For example people will sometimes ground themselves through a 10 mega ohm resistor. This tends to bring them to ground voltage, but they are protected from a deadly shock because most voltages cannot push a lethal current through 10 megs.

  • pull up or pull down:

Sometimes a component will have a very high resistance to both the positive and negative side of the power supply and the voltage can easily drift around due to more or less random events. Under these conditions we will often connect a resistance ( typically around 10 K ohms ) to either the positive or negative side of the power supply. If to the positive side it is called a pull up resistor, if to the negative side a pull down resistor.

  • voltage divider:

A voltage divider takes some voltage as an input and has an output that is some fraction of the input ( from 0 to 1 ) A volume control is usually some sort of voltage divider.

Links

  1. Components: Resistors
  2. Resistor From Wikipedia, the free encyclopedia
  3. Pull-up resistor From Wikipedia, the free encyclopedia
  4. Voltage divider rule From Wikipedia, the free encyclopedia


Carbon[edit]

The most common found resistor is the carbor film. Theses are generally the cheapest and most used in devices. The commonly are designed to withstand 1/8, 1/4, 1/2, and 1 watts of power.

Metal Film[edit]

Wire-Wound[edit]

Useful for cheap and accurate resistance, but has significant inductance compared to film resistors. Some may be wound in one direction, others half in one direction half in the other, this second method reduces but does not entirely eliminate the inductance. Very common in the range of 5 watts and up. Beware of these for use.

Precision[edit]

Potentiometers[edit]

A Potentiometer is a resistor that has a third connection somewhere between the two main terminals. This connection is movable and if put at one end of the resistor will have no resistance between that end of the resistor and the full resistance to the other end. By moving the connection ( sometimes called a tap ) we can control the resistance to each end of the pot, but the sum of the two resistances always equals the total resistance of the potentiometer. A potentiometer is often used as a sort or adjustable voltage divider. There is an electriclly adjustable version: Digital_Potentiometers


Uses

  • Adjustable voltage divider.
  • Volume control.
  • Variable resistor ( sometimes used when the correct value of resistance is not know or available, then the pot is use: it is adjusted, perhaps just once, after the circuit is built – to “tweak” the circuit into operating correctly.
  • Trim or 0 adjustment

External Links Potentiometer From Wikipedia, the free encyclopedia( inc. Schematic and Picture )