Author Topic: [b]resistors and colors[/b]  (Read 7272 times)

jimbob

[b]resistors and colors[/b]
« on: October 07, 2003, 04:55:20 PM »
I recently bought some resistors from mouser and trying to figure out why the colors are not the same as the ones im used to.. for example...a typical 100 k resist colors are blk-brn- yel..my 100 k resist from mouser are=br-blk-blk-ornge- brn 50ppm.. this mouser one seems to have xtra color lines..are they the same? i needed these to be min 1/4 watt rating... did i accid buy cheapos or something totally wrong?
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

Andy

[b]resistors and colors[/b]
« Reply #1 on: October 07, 2003, 06:14:17 PM »
someone correct me if I'm wrong.  Those are 100 Ohm with a 3% tolerance
Andy

aron

[b]resistors and colors[/b]
« Reply #2 on: October 07, 2003, 09:23:26 PM »
hmmm, I've never seen those.

The Mouser package has the value on it right? What does it say?

What does your meter say?

Mike Burgundy

[b]resistors and colors[/b]
« Reply #3 on: October 08, 2003, 10:15:27 AM »
http://www.leonaudio.com.au/res-code.pdf
More bands than the usual 4 are possible, for high-accuracy resistors (usually one more band)
The tolerance band is usually slightly off-set to identify it.
br-blk-blk-ornge- brn
would be
1/0/0 multiplier 3 tolerance 1
so its a 100 *10^3 = 100k, 1% resistor.

[b]resistors and colors[/b]
« Reply #4 on: October 08, 2003, 11:44:46 AM »
What's the difference between 1/4 watts and 1/2 watts resistances?
wich ones do we use?
thanks

Mike Burgundy

[b]resistors and colors[/b]
« Reply #5 on: October 08, 2003, 12:46:16 PM »
Watts is a measure of power. Power (P) is the product of the voltage (V) over a certain part and the current (I) through it - V*I=P , expressed in Watts.
a 1/2 W can dissipate more power than a 1/4 (twice as much, in fact), meaning it can handle twice the current at the same voltage etc. It does not mean it automatically does this - how much power is dependant on the parts value and the circuit around it, not the parts power rating.
1/4W is fine for practically anything in effects, and has a nice small size. Carbon resistors of the most common size are 1/4W. Metal film resistors (different construction, same function) of the same size usually are 1/2W.

For this project, 1/4W will do so just get what's easiest.

aron

[b]resistors and colors[/b]
« Reply #6 on: October 08, 2003, 07:08:02 PM »
Thanks Mike!

If I am every in doubt, I always meaure with my multimeter before using.

jimbob

[b]resistors and colors[/b]
« Reply #7 on: October 09, 2003, 12:00:43 AM »
Thanks everyone...i figured it out.
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

[b]resistors and colors[/b]
« Reply #8 on: October 09, 2003, 01:11:44 PM »
thanks a lot.
another question, is there a method to draw a good layout? i read that aron prefers to stick to the schematic, but if the circuit grows bigger, you want to use less space. thanks

aron

[b]resistors and colors[/b]
« Reply #9 on: October 09, 2003, 03:50:32 PM »
Read the golden rule in the build pictorial.

As long as you connect the points correctly, the schematic will work.

About the only rules that I abide by are:

Input and output are as far apart as possible.
If at all possible, no output signal wraps back over input signal.
Single point grounds.
Minimal use of jumpers (if any).

Just draw version on a piece of paper until you get a good layout and then copy it into your book.

[b]resistors and colors[/b]
« Reply #10 on: October 10, 2003, 03:07:35 AM »
ok! thanks aron..
i remembered the golden rule, but the four rules you mentioned are really interesting..
what do you mean by single point grouds? i read"connect every ground points together on the board(a sort of ground line i guess) then the line goes to ground."

i'll buy all the stuff tomorrow, and i'll let you know when i have a problem building this.
i still have lots of questions about the enclosure work, but io'll try to have a working board before thinking about the enclosure.

Thanks again Aron!!!

aron

[b]resistors and colors[/b]
« Reply #11 on: October 10, 2003, 02:21:26 PM »
Yes, on my layout see the ground on the bottom and in one place?

All the jacks, everything connects to that point.

Good luck and I will be here to answer your questions if you have any.