Macy
South Of Insanity
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September 6th, @09:20PM
| Ideas, Suggestions... UPDATE
and Links.
Since we have a new forum to work with and some of you have already gotten a chance to settle in I thought now would be a good time for suggestions and ideas. Feel free to post any suggestions you may have and also any FAQ info you can think of.
We have a topic started where you can post sites that you can recommend to buy Electronic Parts (thanks Riss!) which will eventually be added to the FAQ and I see that drjim  has kindly posted several sites where you can find printed circuit board fabricators Here, feel free to add to those also.
Suggestions and comments are always welcome and a special thanks goes out to each of you for making this forum possible!
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Jason
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| Re: Ideas, Suggestions...
FAQ entry:
Ohms Law.
Voltage devided by Current times Resistance (E/I X R) Where Voltage is "E"(also "V" can be used), Current is "I", and resistance is "R"
If a circuit is 12V, 2A, then (E/I, or 12/2) the resistance is 6 Ohms.
Conversly, if a circuit is 1A, and 5 Ohms of resistance, then (I X R, or 1 X 5) the Voltage is 5V.
One example of a practical application, is figuring out a current limiting resistor needed for a LED.
Say, you have 12V (A car power system, for instance) and a bright, shiny new Blue LED you want to put in the dash. On the package, the LEDs current is rated at 20mA (0.020A)
So, We have 12V, and need only 0.02A, so E=12, I=.02, E/I, or 12/.02 = 600. Your LED would require a 600 Ohm resistor, to run on 12V. Lower than 600, and the LED will be overdriven, leading to premature failure.
Maybe someone has some good links to online Ohms law, and Watts law calcs?
-Jason
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usa2k
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edit:
October 11th, @08:08PM
|  Re: Ideas, Suggestions.....
Here is a good link to good links 
»www.ifigure.com/engineer/electri···tric.htm
Google is my friend!
Maybe here too »www.101science.com/101_calculati···culators |
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rockotman
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edit:
October 14th, @07:15AM
| reply to Macy
Re: Ideas, Suggestions...
How about some circuit analysis tools.
I use Orcad (for layout and schematic entry) and its bundled analysis package (PSpice) at work quite often.
Orcad has a nifty little demo download (of an earlier release) that lets you run their software to do the layouts and analyses, and the only limitation is in circuit size that you can save and simulate.
I find that the demo version is kind of nifty to have at home, especially when troubleshooting one of those little projects where you just can't quite figure out why something isn't working quite the way you think it should.
I have written training material for use by others where I work, so if anyone wants to download the demo and play around, I will be more than happy to try and answer any questions that you may have regarding how to get the program to do what you want it to do.
I have been using PSpice since the old days (I think I started in 1988) when it was first released by MicroSim and you had to enter the circuit as a netlist in ascii text format. It has come a long way.
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rockotman
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| reply to Macy
And for fun reading regarding circuits or other geeky endeavors, I find Bob Pease to be a great source of humor - that also teaches a lesson.
Bob is a long time analog design guy for National Semi, and writes a monthly article for one of the trade rags. He will always provide a lesson while making you laugh. Some of best articles can be viewed here. Sign up for the on-line verions of Electronic Design if you want to see more of his articles.
p.s. - He hates Spice, and alaysis tools in general. 
But his hatred teaches a valuable lesson. You can't necessarily design the best circuit with them, but you can sure as heck find out what won't work.
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Jason
Dear Penthouse Forum
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| reply to Macy
Resistor Color Codes:
Those color-bands on a resistor are used to determine their value. (Measured in Ohms)
(I will add a couple pics tomorrow)
First: The "Magic Decoder ring"
Color - Value
Black - 0
Brown - 1
Red - 2
Orange - 3
Yellow - 4
Green - 5
Blue - 6
Violet - 7
Gray - 8
White - 9
Gold - 5%
Silver - 10% (more on this later)
Okay. On a resistor, it will typically have 3, or 4 bands. If theres 4, the 4th band should be gold, or silver. This is the resistors "Tolerance" The deviation from its stated value that would be allowed.
For instance, if the resistor is supposed to be 100 ohms, but has a gold (5%) band, it can be up to 5% different in either direction from its sated value. (95 Ohms, to 105 Ohms). A silver band indicates a 10% tolerance, and no band means 20%, (IIRC)
There are other colors of tolerance, but thats outside the scope of this write-up.
Now, with that out of the way, lets figure out how to read a resistor.
With the tolerance band on the right (4th band) starting at the left we have the first band. (First significant value), the second band (Second significant value) and the third band (Multiplier)
With the multiplier, simply add that colors # of zeros to the end of your first, and second significant vales.
Its a bit easier in example.
Lets take a resistor, we'll say its bands are Brown, Red, Yellow and Gold.
Starting at the first band: Brown = 1
The second band: Red = 2
The third band: Yellow = 4
So we have 124. But, remember the 3rd band is the multiplier If its yellow (4) it means to add 4 zeros to the end of the first 2 numbers. So 124, becomes 120,000, or 120K Ohm. With the gold tolerance band (5%) in reality, the resistor can be anywhere from 114,000, to 126,000 ohms (+/- 5%) and still be "within spec"
Lets try one more.
Yellow, Green, Black, Silver.
Yellow = 4
Green = 5
Black = 0
Silver = 10%
Heres a bit of a curve ball. The 0 for the multiplier is just that.. Add, zero zeros to the end of the first 2 numbers.
We end up with a resistor that is 45 Ohms. It can be anywhere from 40.5 to 49.5 ohms, and be in the rated 10% tolerance.
Why a tolerance?
Well, as much of a science as these things are to manufacture, the methods arent perfect. They can make resistors "Dead-On" but theyre quite expensive, and hard to find. Its a *lot* cheaper, and easier to make these (Specifically, Carbon-composition type) resistors with a built-in "fudge factor". Most consumer level resistors are in the 5% tolerance category, and most electronic circuits have no problem with this tolerance.
Ill add some pics tomorrow.
-Jason
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rockotman
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edit:
October 14th, @05:10PM
| reply to Macy
Don't foget the saying to remember the order of the code...
Bad Boys Rob Our Young Girls But Violet Goes Willingly
0 1 2 3 4 5 6 7 8 9
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Jason
Dear Penthouse Forum
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clubs: | LOL.. Yeah, but I was trying to keep it "G" rated
-Jason
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rockotman
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clubs: | Edited for family content.:D |
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usa2k
Please PRAY for Rebekah
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clubs: | Re: Ideas, Suggestions.............
Probably why I never learned that sentence.
I just memorized the numbers/colors -- not that hard.
Still, with SMT (Surface Mount Technology) and resistors that say 2K7 for 2700 ohms, the color bands are more legacy now. |
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Jason
Dear Penthouse Forum
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| Yeah, but experimenter level electronics geeks still play with breadboards and "Big" components..
(Well, At least *I* still do anyway )
-Jason
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rockotman
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| reply to usa2k
said by usa2k :Probably why I never learned that sentence. Once upon-a-was, it was even more politically incorrect.
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drjim
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| reply to rockotman
Re: Ideas, Suggestions...
Pease is a wonderful guy. I've met him a few times at conferences where he spoke. Very entertaining, knowledgeable, and friendly. He's one of us cranky old Geeks that you can't get any Floobydust past!
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kikos77769
join:2005-12-02
44366 | reply to Macy
That is an excellent idea
www.binarydeals.ca (great deals, excellent service) |
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MrFixitCT
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edit:
December 2nd, @06:28PM
| reply to rockotman
said by rockotman :Don't foget the saying to remember the order of the code...
Bad Boys Rob Our Young Girls But Violet Goes Willingly
0 1 2 3 4 5 6 7 8 9
we could add the ending for the tolerance bands:
Get Some Now
Gold (5%) Silver (10%) None (20%)
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The Monkey
I like bananas
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New York, NY | I find the following site to be helpful for resistor values:
»samengstrom.com/elec/resistor/5band.html
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The Monkey |
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The Monkey
I like bananas
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New York, NY | Here's another magazine/site that I like a lot:
»www.makezine.com/
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The Monkey |
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ohms2
@85.195.x.x | reply to Macy
ohms law »www.the12volt.com/ohm/ohmslaw.asp |
|
Splitpair
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| reply to rockotman
said by rockotman :Don't foget the saying to remember the order of the code...
Bad Boys Rob Our Young Girls But Violet Goes Willingly
0 1 2 3 4 5 6 7 8 9
Well since we are on color and about to get us all banned for life how about a change of subject.
Telco color code.
B=blue
O=orange
G=green
Br=brown
S=slate (not grey)
W=white
R=red
Bk=black
Y=yellow
V=violet (not purple)
Tip: Pairs
White 1-5
Red 6-10
Black 11-15
Yellow 16-20
Violet 21-25
Ring: Pairs
Blue First Pair 1,6,11,16,21
Orange Second Pair 2,7,12,17,22
Green Third Pair 3,8,13,18,23
Brown Fourth Pair 4,9,14,19,24
Slate Fifth Pair 5,10,15,20,25
Binders:
B/W 1-25
O/W 26-50
G/W 51-75
Br/W 76-100
And on and on.
FWIW Telco cable is built in 25 pair groups or binders. Any cable over 25 pairs will have binders which are the 25 pairs twisted and then wrapped in a multi-colored colored string (old days) or two colored plastic “binders”.
For example a pair in a 25 pair cable consisting of a black wire with blue stripe mated with a blue wire with a black stripe is pair 11. Now lets go to a cable with over twenty five pairs and lets say the same pair was in a binder/group wrapped with a brown/white string it would be pair 86. Make sense?
Wayne
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rowd
join:2000-09-06
Chicago Heights, IL
| reply to Jason
Go here.....
»hyperphysics.phy-astr.gsu.edu/hb···ame.html
»hyperphysics.phy-astr.gsu.edu/hb···ame.html
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Futhermore Senator |
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