*** Electronics FAQ ***

FLECOM

Modder(ator) & [H]ardest Folder Evar
Staff member
Joined
Jun 27, 2001
Messages
15,637
This FAQ is a work in progress, please check out the Case Modding FAQ in the main Cases / Case Modding section for more stuff...

If you have any suggestions/additions please PM me

thanks
-Frank aka FLECOM
 

FLECOM

Modder(ator) & [H]ardest Folder Evar
Staff member
Joined
Jun 27, 2001
Messages
15,637
Electronics Vendors
Commercial Sellers
Jameco http://www.jameco.com/
Digikey http://www.digikey.com/
Mouser http://www.mouser.com/
Newark http://www.newark.com/
Electronix http://www.electronix.com/
Parts Express http://www.partsexpress.com/

Electronics Surplus Vendors (less selection, better prices)
BG Micro http://www.bgmicro.com/
All Electronics http://www.allelectronics.com/
Hosfelt http://www.hosfelt.com/
MPJA http://www.mpja.com/
American Science and Surplus http://www.sciplus.com/
Electronic Goldmine http://www.goldmine-elec.com/
Herbach & Rademan http://www.herbach.com/

LCD FAQS

Laptop LCD FAQ <~ Everything you'r probably going to ask about Laptop LCD's
Text LCD FAQ <~ Everything you'r probably going to ask about Serial & Parallel Text LCD's
Video LCD FAQ <~ Everything you'r probably going to ask about Video (Color) LCD's
LCD Scavenging FAQ <~ Everything you'r probably going to ask about taking LCD's out of stuff you already have
Everything Else FAQ <~ All sorts of stuff from DIY Projectors to inverting your LCD with polarizer to adding input buttons

LEDs: Basics - resistors to use
To find the value of the resistor to use with your led, use this formula:
Resistance(Ohms) = (Supply Voltage - Forward V of LED)/ Current (A)

You should be able to find these values easily, usually on the back of the package or on the website you got them from. Current for LEDs is measured in mA. you will need to move the decimal over 3 places to get to Amps.

Example - 20mA = .02A

So to run a 3.5V blue led from 5V at 20mA (0.02Amps)...
resistance = (5V - 3.5V) / 0.02A = 75ohms
If you cant find a resistor of the exact result (which you usually wont) try to find the closest one, try to go with a little more resistance, than less, to prevent damage to the resistor or LED

If you still dont get it (or are lazy ;)) use Linear's handy-dandy web calculator
http://www.bit-tech.net/article/68/

LEDs: Basics - Polarity - postive/negative

The longer lead is the + side. If the leads are the same size look carefully at the lens, you will see a division, the small divided side is the positive lead and the large divided side is the negative lead. You can always do trial and error, if one wiring doesn't work, than reverse it, the most damage you could do is burn out the LED but thats very unlikely.

LEDs: Basics - Parallel, Serial


Parallel LEDs are wired the same as a single ones with many resistor/LED curcuits connected across a single powersupply rail. Although you can use one resistor for multiple LED's it is generally strongly recommended that each LED should have it's own resistor to prevent one LED consuming more power than it should and to prevent overloading the resistor.

Series LEDs are two or more leds sharing one resistor. To calculate the resistor the "LED voltage" get the sum of all the led's voltages in the circuit. So for two of our 3.5V blue LEDs the voltage is now 3.5V + 3.5V = 7V. Obvously the 5V supply won't work for this one. So if you wanted to do this you would need to connect your circuit to the +12V rail of your PSU and calculate the supply voltage as 12 instead of 5

LEDs: DIY LED Fans
http://www.bit-tech.net/article/73/
http://www.themodfathers.jolt.co.uk/?page=&action=show&id=6131

LEDs: HDD "Activity" meter
http://www.bit-tech.net/article/83/

LEDs: Keyboard LEDs
http://www.virtual-hideout.net/guides/keyboard_led/index.shtml
http://www.themodfathers.jolt.co.uk/?page=&action=show&id=6128

LEDs: Knight Rider mod
http://www.bit-tech.net/article/82/1 < DIY
http://www.twistedmods.com/modules.php?name=Sections&op=viewarticle&artid=191 < Front of antec/chieftec case, premade kit

LEDs: LED Meter
http://casemods.pointofnoreturn.org/cpumeter/ < good howto to make an LED Meter
http://www.twistedmods.com/modules.php?name=Sections&op=viewarticle&artid=184 < using your led meter with winamp
*Note that connecting LEDs directly to your parallel port can seriously damage it! I very much recommend you use Uller's design with a 74HCT373 chip, its inexpensive and is sold at radioshack

LEDs: NIC LED Mods
Great for router pcs!
http://www.virtual-hideout.net/guides/nic_leds_mod/index.shtml

LEDs: Replacing LED in Optical Drives
http://www.twistedmods.com/modules.php?name=Sections&op=viewarticle&artid=124
http://www.virtual-hideout.net/guides/cdfdd_led_mod/index.shtml
http://www.themodfathers.jolt.co.uk/?page=&action=show&id=6118

LEDs: Replacing LED in Optical Mice
http://www.twistedmods.com/modules.php?name=Sections&op=viewarticle&artid=37

LEDs: replacing Power & hard drive LEDs on the front of your case
Well, first you need to determine if it is a 5mm LED or a 3mm LED. Pick up some suitable replacements - any LED's rated from 2v - 5v forward voltage will probably work. A lot of people will tell you you need resistors but it's really not necessary. Chances are the original LED's were only 2v LED's and if you replace with 5v, it'll probably work fine but just a fraction less bright....
These LED's are usually held in place more times than not by little plastic clips. Just spread the clips and remove the LED. The LED will usually have two wires attached... One is usually black or white - this would be ground. The other is usually colored, like red or green - this would be positive. At this point you can just snip the old LED off or better, split open the black shrink wrap with an exacto knife and desolder it. Next take the new LED and determine the positive and negative on it. The positive usually is the longer pin, but not always. The negative is the shorter pin and if you can see inside the LED, the larger dish is connected to the negative pin. Check this thread for an illustration. A battery of some sort, (a couple of flashlight batteries taped together in series is fine), is helpful in this situation. You can pretest the LED to verify the positive and negative by connecting the pins to a couple of wires and tapping the wires on the ends of the battery.
Then just cut the pins to fit, solder the correct wires to the pins, shrink wrap it, - slip the shrink wrap on before soldering (or use electrical tape tightly wrapped) and snap it back in the clips...

To summarize: Figure out how yours are plugged in, take em out, put in new ones the same direction. You can always do trial and error, if one wiring doesn't work, than reverse it, the most damage you could do is burn out the LED but thats very unlikely.

If you want more info, check out this writeup:
http://www.virtual-hideout.net/guides/case_leds/index.shtml

LEDs: Strobes
http://www.bit-tech.net/article/80/
 

thaltek

Limp Gawd
Joined
Sep 15, 2009
Messages
206
i would like to see the math part expanded a bit for those of us whom are newbies at electronics......

===============================================================================================================================

ELECTRICITY: the behavior of electrons which can be static or dynamic in nature.

-VOLTAGE: Without getting technical static electricity is a difference in the number of electrons in a given system, the difference is measured in units of Volts, (V).

-CURRENT: the dynamic flow of electrons through a circuit measured in Amps,(A). An easy way for beginners to think about current is water flowing through pipes.

-RESISTANCE: something that inhibits the flow of current, commonly measured in Ohms,(&#937;).

-WATTAGE: the amount of work done in a given time frame, commonly measured in Watts,(W).

-CAPACITANCE: the temporary storage of charge, commonly measured in Farads, (F).

-INDUCTANCE: simalar to a resistor in setup but instead uses an electromagnetic field to dampen frequencies, commonly measured in henrys, (H).

===========================================================================================================

Basic conversions
these are the equivalent values to the base unit.... this system also applies to capacitors and inductors.

1&#937;=100c&#937;=1000m&#937;=1000000&#956;&#937;=1000000000n&#937;=1000000000000p&#937;

1G&#937;=1000000000&#937;
1M&#937;=1000000&#937;
1k&#937;=1000&#937;

I have seen several ways in which you will find various components labeled....

slang label / exact value / proper label

4k3&#937; 4300&#937; 4.3k&#937;

4700k&#937; 4700000&#937; 4.7M&#937;

~please do not make a fool of yourself and post a resistance value in slang..... -_- this will be on the test later......

====================================================================================================

Ok, lets look at the formulas and how to manipulate them.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Power formula:

P=(work/time)=V*I

where:
P=Watts, W
V=Voltage
I=Current, A

~example~
lets use a standard 60W light bulb and we know the voltage is 120V. What is the current?
To solve for the current we rearrange the the equation so &#8220;I&#8221; is by itself.

I=P/V=60W/120V=0.5A
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Ohms Law:

V=R*I

where:
V=Voltage
I=Current, A
R= Resistance, (&#937;)

~example~
Using the same lightbulb from the previous example, we know it is running at 120V and 0.5A. What is the resistance? In order to solve for the resistance we rearrange the equation so that &#8220;R&#8221; is by itself.

R=V/I=120V/0.5A=240&#937;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-Voltage drop formula:

R=&#916;V/I

where:
R=Resistance, (&#937;)
&#916;V = change in voltage, (available voltage- needed voltage)
I=Current, A

~example~
you have an led rated at 5V @ 25mA and plan to use an 8V source. What size resistor is needed?

First convert mA to A &#8230;.. 1A=1000mA..... so 25mA=0.025A

R=&#916;V/I=(8V-5V)/0.025A=120&#937;

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
resistors come in several different wattage ratings 1/8W, 1/4W, 1/2W, 1W and higher.... because of this you will need a resistor with an appropriate wattage, for this we will use the power formula. I will use the values determined in the previous example.

P=V*I=5V*0.025A=0.125W or 1/8W

I highly suggest that you use a safety factor and go with a 1/4W resistor. Why? Well if you use a 1/8W resistor it will start to heat up over time the thermal stresses eventually lead to the failure of the resistor....
================================================================================================================================

RESISTORS

resistors inhibit the flow of electrons in a system hence they resist current....
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
for this first problem lets consider the following: you need a very specific resistor that is not commercially available such as 1350470&#937;. Well fear not there is a way to get this resistance!

Resistors in series: R=R&#8321;+R&#8322;+R&#8323;+R&#8324;......

alright we know that we can buy the following resistors: 1M&#937;, 350k&#937;, 470&#937;

so all we have to do is link the resistors end to end like seen below.


pic courtesy of wikipedia

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
well lets consider another problem with resistors. Lets consider the following: you have a pile of 10&#937; resistors laying around but you need 5&#937;.

Resistors in parallel: R=1/((1/R&#8321;)+(1/R&#8322;)+(1/R&#8323;)+(1/R&#8324;))

we plug in the numbers and it turns out that only two 10&#937; resistors wired in side by side will give us 5&#937;... set up is as seen in the pic below.


pic courtesy of wikipedia
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
more details can be found at: http://en.wikipedia.org/wiki/Resistor

=================================================================================================================================

CAPACITORS

its easiest to think of them as rechargeable batteries that can &#8220;instantly&#8221; discharge..... they are useful in that they hold a charge and can dampen unwanted frequencies...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

for this first problem lets consider the following: you need a very specific capacitor that is not commercially available such as 1650&#956;F. Well fear not there is a way to get this capacitance! Unlike resistors, capacitors do not allow &#8220;when working&#8221; current to flow across so we are going to switch things up.....

Capacitors in parallel: C=C&#8321;+C&#8322;+C&#8323;+C&#8324;......

alright we know that we can buy the following capacitors: 1600&#956;F, 50&#956;F

so all we have to do is link the resistors end to end like seen below.


pic courtesy of wikipedia

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
well lets consider another problem with capacitors. Lets consider the following: you have a pile of 100&#956;F capacitors laying around but you need 33.3&#956;F.

Capacitors in series: C=1/((1/C&#8321;)+(1/C&#8322;)+(1/C&#8323;)+(1/C&#8324;))

we plug in the numbers and it turns out that only three 100&#956;F capacitors wired end to end... set up is as seen in the pic below.


pic courtesy of wikipedia
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
more detail can be found at: http://en.wikipedia.org/wiki/Capacitor

===================================================================================================

INDUCTORS

for this first problem lets consider the following: you need a very specific inductance that is not commercially available such as 1350470H. Well fear not there is a way to get this inductance!

Inductors in series: L=L&#8321;+L&#8322;+L&#8323;+L&#8324;......

alright we know that we can buy the following resistors: 1MH, 350kH, 470H

so all we have to do is link the inductors end to end like seen below.

http://en.wikipedia.org/wiki/File:Inductors_in_series.svg
pic courtesy of wikipedia

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~
well lets consider another problem with inductors. Lets consider the following: you have a pile of 10H inductors laying around but you need 5H.

Inductors in parallel: L=1/((1/L&#8321;)+(1/L&#8322;)+(1/L&#8323;)+(1/L&#8324;))

we plug in the numbers and it turns out that only two 10H inductors wired in side by side will give us 5H... set up is as seen in the pic below.

http://en.wikipedia.org/wiki/File:Inductors_in_parallel.svg
pic courtesy of wikipedia
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~
more details can be found at: http://en.wikipedia.org/wiki/Inductor
 
Last edited:

rjolin01

[H]ard|Gawd
Joined
Aug 31, 2008
Messages
1,400
so far what does this thread have to do with case modding and such?
 

FLECOM

Modder(ator) & [H]ardest Folder Evar
Staff member
Joined
Jun 27, 2001
Messages
15,637
so far what does this thread have to do with case modding and such?
back in the long long ago people used to (spoiler alert) actually mod their computers themselves... they used primitive tools like drills, soldering irons and rotary tools... it may seem shocking and barbaric, but not that long ago everyones case was beige and no manufacturer would make something silly like a "fan bus", computers in different colors besides beige or lighting for a computer... :rolleyes:

come on seriously?
 

PedroDaGr8

Limp Gawd
Joined
Feb 17, 2004
Messages
489
Haha, I just read this post! I remember people sharing schematics for PWM fan controllers, the joining of the 5V and 12V line to get an 8-9V line for a quieter fan, dryer duct mods to the window to expel heat, etc.

Basically, case modding wasn't about buying a bunch of prefabbed modules and putting them together it was about actually freaking modding your boring ass beige case. Painting it, cutting holes in it for more fans, eventually cutting holes to make windows, etching patterns into the windows, reappropiating things like CCFLs (none were made for computers at that time) to work with a 12V system, etc.
 

Lt. Dan

Limp Gawd
Joined
Dec 25, 2000
Messages
287
Flecom damn man it's been a long time on this board. I just got back to building a rig and was surprised to see you still at
 
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