| Electronics > Beginners |
| Multimeters and Resistors |
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| Kohlrak:
--- Quote from: Nusa on November 24, 2017, 11:47:53 am ---Many informal color tests on the internet. Here's one: http://enchroma.com/test/instructions/ Here's the manual for the common centech meter: https://manuals.harborfreight.com/manuals/98000-98999/98025.pdf Harbor Freight periodically has free-with-purchase store coupons, so any hobbyist who lives near a Harbor Freight has probably grabbed one or more over time. Including me. --- End quote --- Oh wow. And here i thought the diode was to help people figure out which side was which if the paint came off or something. I found one that looks like a 45kohm according to the meter, but it looks to be 46kohm, but i'm not supposed to even have either. The closest one is supposed to be 47kohm, according to the packaging. It's so tiny i just can't tell if that second band is green, blue, or black. Wait, if i hold the resistor's pins against the needles it registers 45.2, but if i lay it down and test it, i get 46.3. It comes from touching the needle, not the resistor, but if i hold the 2 needles like an idiot asking to shock my heart out of rhythm, too much resistance. Lesson learned, put it down on something. But, why that level of change? And how have i not killed myself being an idiot? Well, at least some lessons are being learned. EDIT: --- Quote ---Deutans are people with deuteranomaly, a type of red-green color blindness in which the green cones do not detect enough green and are too sensitive to yellows, oranges, and reds. As a result, greens, yellows, oranges, reds, and browns may appear similar, especially in low light. It can also be difficult to tell the difference between blues and purples, or pinks and grays. --- End quote --- I noticed certain ones did give me a very hard time. And here i thought that green was supposed to be the easiest color for all humans to reliably distinguish, hence why 16bit coloring has an extra green bit. |
| Vtile:
--- Quote from: IanB on November 24, 2017, 11:32:07 am --- --- Quote from: Kohlrak on November 24, 2017, 11:25:44 am ---So it's not scientific notation, but a direct "see 2 color numbers, with this many zeros after it decided by third band." That makes it easier. So black brown black for 1 ohm. --- End quote --- The third band is a multiplier: x0.1, x1, x10, x100, etc. Therefore 1 ohm is brown black gold (10 x 0.1 = 1). --- End quote --- The easiest method to sort this color coding in someones head (my own opinion) is that you learn that black = 0, brown = 1, Red = 2, Orange = 3 and then learn (...to read from the cheat sheet like pros do) the data represented in each band. ie. Brown-Black-Red-Gold is in plain human language. One - Zero - Two zeros - tolerance +-10% from nominal value, which makes a 1000 ohms nominal and 1k in engineering lingo. Letter k comes from the word kilo, which means thousand (https://en.wikipedia.org/wiki/Metric_prefix). The trap here, is that when you get first resistor in your hands that do have 5 or 6 bands you are totally lost a moment since it does have three value bands and multiplier band, again do like pros do, look from the fact/cheat sheet. In moment of panic and self-doubt use the meter to make a sanity check. If that doesn't help take a hammer. |
| Kohlrak:
--- Quote from: Vtile on November 24, 2017, 12:23:54 pm --- --- Quote from: IanB on November 24, 2017, 11:32:07 am --- --- Quote from: Kohlrak on November 24, 2017, 11:25:44 am ---So it's not scientific notation, but a direct "see 2 color numbers, with this many zeros after it decided by third band." That makes it easier. So black brown black for 1 ohm. --- End quote --- The third band is a multiplier: x0.1, x1, x10, x100, etc. Therefore 1 ohm is brown black gold (10 x 0.1 = 1). --- End quote --- The easiest method to sort this color coding in someones head (my own opinion) is that you learn that black = 0, brown = 1, Red = 2, Orange = 3 and then learn (...to read from the cheat sheet like pros do) the data represented in each band. ie. Brown-Black-Red-Gold is in plain human language. One - Zero - Two zeros - tolerance +-10% from nominal value, which makes a 1000 ohms nominal and 1k in engineering lingo. Letter k comes from the word kilo, which means thousand (https://en.wikipedia.org/wiki/Metric_prefix). The trap here, is that when you get first resistor in your hands that do have 5 or 6 bands you are totally lost a moment since it does have three value bands and multiplier band, again do like pros do, look from the fact/cheat sheet. In moment of panic and self-doubt use the meter to make a sanity check. If that doesn't help take a hammer. --- End quote --- The correlation to colors and 0s was already sinking in just before reading this. So i assume that, too, 5 and 6 band ones work exactly the same way, instead of the 3rd being a decimal or some other unnecessarily convoluted system? |
| Vtile:
--- Quote from: Kohlrak on November 24, 2017, 12:41:27 pm --- --- Quote from: Vtile on November 24, 2017, 12:23:54 pm --- --- Quote from: IanB on November 24, 2017, 11:32:07 am --- --- Quote from: Kohlrak on November 24, 2017, 11:25:44 am ---So it's not scientific notation, but a direct "see 2 color numbers, with this many zeros after it decided by third band." That makes it easier. So black brown black for 1 ohm. --- End quote --- The third band is a multiplier: x0.1, x1, x10, x100, etc. Therefore 1 ohm is brown black gold (10 x 0.1 = 1). --- End quote --- The easiest method to sort this color coding in someones head (my own opinion) is that you learn that black = 0, brown = 1, Red = 2, Orange = 3 and then learn (...to read from the cheat sheet like pros do) the data represented in each band. ie. Brown-Black-Red-Gold is in plain human language. One - Zero - Two zeros - tolerance +-10% from nominal value, which makes a 1000 ohms nominal and 1k in engineering lingo. Letter k comes from the word kilo, which means thousand (https://en.wikipedia.org/wiki/Metric_prefix). The trap here, is that when you get first resistor in your hands that do have 5 or 6 bands you are totally lost a moment since it does have three value bands and multiplier band, again do like pros do, look from the fact/cheat sheet. In moment of panic and self-doubt use the meter to make a sanity check. If that doesn't help take a hammer. --- End quote --- The correlation to colors and 0s was already sinking in just before reading this. So i assume that, too, 5 and 6 band ones work exactly the same way, instead of the 3rd being a decimal or some other unnecessarily convoluted system? --- End quote --- The resistors that do have more than 4 bands are a bit unclear as what each do mean. In resistors 5 to 7 bands the three first bands represent a value and fourth is multiplier. Yes you are in correct path with your thoughts. The next band (5th) is pretty safe to assume to be always the tolerance, but the rest of the bands can generally be pretty wildly anything, however the 6th band is typically a multiplier for the temperature dependency of the resistance (in parts per million = ppm). The inconsistencies of the system comes from the fact that the coding system have its roots somewhere in 1920s or 1930s with only 3 color bands and fixed +-25% tolerance (or something huge from todays perspective). Edit. PS. Also the body / background color do have its own meaning coded to it, but it is chosen freely by manufacturer as far as I know. Although everyone tries to copy each other and keep the system somewhat logical. Edit2. Hopefully I didn't wrote a total gibberish as sometimes happens when thinking with two languages simultaneously. |
| tpowell1830:
From all of the posts, I have determined that you have a situation where you are "caught between a rock and a hard spot", since you are having troubles reading color bands and also having trouble reading your resistances on your meter. I truly have the color band reading problem as well, so I use my meter. With that said, IMHO, I would would op to simply learn how to use the meter and check each resistor for resistance. I have setup a place on my breadboard for checking resistors quickly by touching a couple of bare wires, which I have set apart a nominal distance and I have my meter leads connected via quick grab clips. I don't even bother looking at color codes unless I am stuck some place without my meter, at which time I always seem to figure out the resistance from the color codes if they are 4 band after looking at different angles and varying light (takes forever). I also recommend that you study a book on basic electronics before you hurt yourself. There are plenty of good books and online tutorials available. Your comment about checking the resistance with your meter and being concerned about your heart has given away that you are not learned at all about electricity and electronics. The resistance of your body was causing the different readings while touching the leads. The meter output is such high resistance and low voltage that you would not be harmed by the current. |
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