Multimeters and Resistors

[Kohlrak]

As you'll see from one of the attachments, I have a mess of parts, wonderful "lab" and all kinds of fun stuff with the lab and didn't come with the lab. I've experimented with ATMega 328P-PUs, got some fun things working for it, but would like to try to make things from scratch that I could drive with it. I have a nifty IR LED with an IR sensitive photoresistor ("receiver"), I even have visual spectrum photo-resistors. I have cool parts and doo-dads, but I'd love to learn how to use them. I got 2 books that came with the lab, 1 book that I bought that i managed to get through (focused on digital circuits). I'm not really interested in AC, outside of making something to convert it to DC (actually, i'd rather not make something that i'd plug into the wall and ends up catching the house on fire).

Anyway, the bane of my existence and learning experience is these resistor color codes. I'm not color blind, but half the time i'm looking at these things, I can't tell yellow from red from orange, red from brown from orange, you get it. I've read other places that the paint jobs anymore are horrible, so it might not just be my eyes. I was hoping to try to gain some familiarity with it (or just straight up make a cheat sheet with contrastive resistors just so i can tell the colors apart) by using the resistor modes on my multimeter, but I don't know what the readout should look like. I also find it strange that everything is in terms of 2, but i'm not sure if I should be dividing or multiplying by 2 to figure out what my resistor is. I figure the black plug should be in "COM" but i'm honestly not sure which plug is should be using for which modes, nor do I know what all the modes are. I think the one mode is a diode mode, which seems absolutely pointless.

Honestly, I don't remember if the thing even came with a manual or not, but if it did, it got lost from all the moving of the parts constantly. Supposedly out of my resistor pack from Radio Shack, I have the following.

10 of 10?, 1k?, 10k?, and 100k?.
8 of 47?, 100?, 470?, 2.2k?, 4.7k?, and 1M?.
4 of 150?, 220?, and 15k?.

They're all 5% tolerance, so that's easy to identify.

Each of 5% tolerance.  So, i tried to use that kind of power of deduction that the strips of 10 should be of particular interest to me and be the easiest way to identify what some of the colors are, right? As predictable, either my eyes are really bad, i'm doing this wrong, or the actual number of resistors is not what's printed on the package. Not a big deal for me, as i've bought this stuff a long time ago, but i'd really like to get over this hump.

So, I have a few questions (just to get my foot in the door, mostly):

1. For those of you who've done this longer than me, out of what was advertised, what combination do you feel to be the most efficient (fewest resistors displaying the most colors) that i could tape to a piece of paper to have a physical cheatsheet for dealing with various lighting conditions?

2. What should I set my multimeter to, and what should I expect to see, when looking for the resistors to question 1 (I probably don't need an exhaustive list, if it's alot of work for you)?

3. I noticed that my crystals froze the ATMega 328P-PU (Arduino CPU) when one of the capacitors comes undone (22?F, I think, as they just have "22" written on them). When i disconnected both of them from the crystal (16MHz) it worked again. I can't remember if i plugged it directly to ground or not, implying that the capacitors are not actually needed (i wasn't afraid of frying it or anything, since these chips are so cheap). Why is this?

4. Realistically, what is the problem with doing this?

5. Anything I can do with these to slow them down to 16KHz, or hook them up to something else to use them? I only have 11 ATMega chips, but I have like 50 of those crystals. I was curious if I could make an interrupt timer, buzzer, or something like that out of them, and how I would even go about it (maybe even something sensitive to the photoresistors or the IR detector).

[IanB]

With my resistor pack I wrote the values on the little paper strips they are attached to so I can quickly find  a value I want, and I sorted them into one of those multi-compartment project boxes with all the same numeric values in the same compartment. So all the 10, 100, 1k, 10k, 100k 1M into one compartment, 2.2, 22, 220, 2.2k 22k etc into the next compartment, and so on.

[Brumby]

I could read a resistor colour code from 4 feet away on a carbon film resistor ... but when they introduced the metal film with the blue body, I'm challenged to read some values with my head magnifier at times!!

I'd really like to knee-cap the bozos that came up with that.

[Bashstreet]

I could read a resistor colour code from 4 feet away on a carbon film resistor ... but when they introduced the metal film with the blue body, I'm challenged to read some values with my head magnifier at times!!

I'd really like to knee-cap the bozos that came up with that.

Yes i do not find those blue ones fun at all... Any case i end up always just using my meter to check the values.. 

[Brumby]

I often do, too.

[sleemanj]

1. Forget about colour codes, with typical chinese resistors it's so hard to read.  That's what a multimeter is for.

2. If your multimeter is set to a range which is too low to show the resistor's value it will indicate an overload by printing a "1" in the left most position and nothing else (maybe a decimal point), ie "1   " which is different to "   1".  Your meter is manual ranging, each time you go "up" a range (ie from 200 to 2000) you lose 1 digit of precision, that is, the 0-200 range can measure 0.1 ohm units, the 2000 range can measure 1 ohm units, the 20k range can measure 10 ohm units, the 200k can measure in 100 ohm units, and the 2000k (2M) range can measure in 1k units. For example given a resistance of 123 Ohms, the 200 range will show 123.0, the 2000 range will show 123, the 20k range will show 0.12, the 200k range will show 0.1 and the 2000k range will show 0.  In other words, just buy an autoranging meter :-)

3. The caps may or may not be necessary, and if they are your construction (especially on a breadboard) may well have enough inherent capacitance on it's own.  What will not be so good though as you found is to have it unbalanced.

4. With the caps?  Nothing, it will work (oscillate and therefore the atmega can run) or it won't (in which case nothing will happen).

5. You want to run the ATMega a t 16 KILO Hertz?  16KHz is pretty much silly.  16MHz is a standard speed.  There's no reason you can't run at 16KHz (I think from memory, you'd have to check the datasheet to be sure), but to be a little blunt if you don't know how to use a multimeter, you are trying to run before you can walk here.  Anyway if you wanted to stay within the Arduino environment you would have to create a custom board definition in order to set the AVR frequency in order that timing (millis(), delay() etc) was accurate.

[Kohlrak]

1. Forget about colour codes, with typical chinese resistors it's so hard to read.  That's what a multimeter is for.

Good to know i'm not a looser for having trouble reading them, then.

2. If your multimeter is set to a range which is too low to show the resistor's value it will indicate an overload by printing a "1" in the left most position and nothing else (maybe a decimal point), ie "1   " which is different to "   1".  Your meter is manual ranging, each time you go "up" a range (ie from 200 to 2000) you lose 1 digit of precision, that is, the 0-200 range can measure 0.1 ohm units, the 2000 range can measure 1 ohm units, the 20k range can measure 10 ohm units, the 200k can measure in 100 ohm units, and the 2000k (2M) range can measure in 1k units. For example given a resistance of 123 Ohms, the 200 range will show 123.0, the 2000 range will show 123, the 20k range will show 0.12, the 200k range will show 0.1 and the 2000k range will show 0.  In other words, just buy an autoranging meter :-)

My multi-meter doesn't seem to be that technical (1s are always printed from the right). I'd love to know what i'm supposed to be seeing, but I can never figure out what i'm even playing with to begin with, so i know if i should be dividing the number i see on the screen by 2 or what.

3. The caps may or may not be necessary, and if they are your construction (especially on a breadboard) may well have enough inherent capacitance on it's own.  What will not be so good though as you found is to have it unbalanced.

I read that too much capacitance can slow it down, but i'm not sure how much it actually matters at the end of the day. Are we talking 1Hz for every 100 microfarad, or is it 1MHz for every 1 microfarad?

4. With the caps?  Nothing, it will work (oscillate and therefore the atmega can run) or it won't (in which case nothing will happen).

Good, no frying, then.

5. You want to run the ATMega a t 16 KILO Hertz?  16KHz is pretty much silly.  16MHz is a standard speed.  There's no reason you can't run at 16KHz (I think from memory, you'd have to check the datasheet to be sure),...Anyway if you wanted to stay within the Arduino environment you would have to create a custom board definition in order to set the AVR frequency in order that timing (millis(), delay() etc) was accurate.

I'm thinking more in terms of slowing it down and sticking it on another pin (what if i want to know how much time has passed but don't want to count individual instruction cycles, for example?). To throw it at 16KHz, in particular, would be to stick it on a speaker to make a buzzing noise. I'm trying to figure out what I could do to slow it down to find more applications for it outside of a clock for a microcontroller, since i have way more crystals than microcontrollers.

but to be a little blunt if you don't know how to use a multimeter, you are trying to run before you can walk here. 

I understand most of the stuff from the atomic level to the programming level, and I even know how to use A multimeter, but i don't necessarily know how this one works, but I also don't have a resistor of known value, so i've run into a chicken-or-egg problem. I've wanted to try my hand at some more analogue circuits using direct current, so i could use my chips for things without buying "shield X" from sparkfun or something. I have a bunch of pieces of things sitting there collecting dust, and I wouldn't mind experimenting with ideas that they don't even have shields for. I've even thought of trying to make some sort of radio receiver to try to pick up truly random noise to quickly generate huge xor encryption keys and things like that.

[sleemanj]

In any resistance range, show what your meter shows with the leads not connected to anything.

In any resistance range, show what your meter shows measuring any resistor.

[sleemanj]

ALso in the picture of your multimeter, take note that you have the probes in the incorrect sockets for measuring resistance.

[IanB]

In any resistance range, show what your meter shows with the leads not connected to anything.

In any resistance range, show what your meter shows measuring any resistor.

It's one of those little CEN-TECH meters from Harbor Freight. It has manual ranges 200, 2000, 20k, 200k, 2000k. It shows 1 on the left of the display if it's over range, otherwise it displays the value.

To measure a resistor you start on the 200 range and if the display shows 1 you turn the dial up through the ranges until you see a value. Then you read the value off the display.

[sleemanj]

It's one of those little CEN-TECH meters from Harbor Freight. It has manual ranges 200, 2000, 20k, 200k, 2000k. It shows 1 on the left of the display if it's over range, otherwise it displays the value.

To measure a resistor you start on the 200 range and if the display shows 1 you turn the dial up through the ranges until you see a value. Then you read the value off the display.

Yes I have a similar model in front of me, but the poster said his doesn't work like that ("(1s are always printed from the right)")  So I'm a little confused.

Anyway, to the poster.

Make sure that you understand

  1. To measure resistance you need the probes in the COM and the V/Ohm/mA sockets (the bottom two sockets)
  2. The symbol for resistance is Omega (a curvey n with feet)
  3. the resistance ranges bottom left quarter of the dial are 2000k through 200
  4. the ranges with "k" suffix measure in k, 123.4 means 123.4 kohms
  5. the ranges without a suffix measure in ohms, 123.4 means 123.4 ohms
  6. if it prints just "1" on the left side of the display, that means it's over-range, move the dial one place clockwise to go to the next range

[IanB]

Here's a picture of the meter measuring a 1.8 k resistor (1800 ohms) on the 2000 ohms range:

[IanB]

Yes I have a similar model in front of me, but the poster said his doesn't work like that ("(1s are always printed from the right)")  So I'm a little confused.

I'm pretty sure it does work like that. I think the OP is just in a bit of a muddle.

[Kohlrak]

https://78.media.tumblr.com/569d5f0239d37dc134568fbafd320c8a/tumblr_ojyg1iC6TK1vhaphlo1_r1_500.gif

Here's a picture of the meter measuring a 1.8 k resistor (1800 ohms) on the 2000 ohms range:

What're the odds you'd have the same one? So, basically, i'm reading the thing wrong, that there's no need to take the output and divide by said number or multiply by said number, which was what i was interpreting so far. So, if I see 1 at 200, I should assume it's either out of range, or i'm dealing with 1 ohm, right?

It seems strange to me that it'd have so many modes if the real limitation is the 4 digits. Anyway, it seems at this point my goal is to look for what i think to be brown gray silver gold (I should have one, as i have more than just that one resistor pack), then throw my multimeter to 2000 and make sure it's similar, then see how it reacts when i set it to other ranges.

I do assume that if i set the thing to 20k i'll have to add some zeros. How many, though?

What's hFE?

And what do I do with the, what i'm asusming to be, some sort of transistor testers? There's 4 pin holes for NPN and PNP respectively.

I'm pretty sure it does work like that. I think the OP is just in a bit of a muddle.

Could be that, too. Issue being, it's hard to concisely experiment when you have 2 variables and no controls. Once I go through these resistors with this image I should be able to go at least a little on my own from there. Just need to figure out how it handles resistors outside of the normal display range at this point, then.

As for the other replies, wow, reply rates seem to be much higher here than i'm used to for tech related forums.

[IanB]

Anyway, it seems at this point my goal is to look for what i think to be brown gray silver gold

A 1.8k resistor (1800 ohms) is brown gray red (18 followed by 2 zeros).

So, if I see 1 at 200, I should assume it's either out of range, or i'm dealing with 1 ohm, right?

If out of range the meter shows a 1 on the left and a dot on the right. If you measure a 1 ohm resistor you will see something like 01.3 on the display.

[Nusa]

Since your resistors are conveniently in strips, leave them there until you actually need to use one.
All the resistors in the same strip are the same, so measure one without removing it from the strip, then write its value on the paper strip on both sides. You just saved yourself a lot of future measurements or puzzling over color codes.
Repeat for your other strips of resistors.

It's possible you have a red-green color deficiency mild enough it's never been diagnosed. That is the most common form of color-blindness (a misnomer in most cases, as they still see plenty of color). If so, it just means you see some colors less brightly than some people, which can make reds/browns/oranges hard to identify except in really good light. If other people have no problem reading off the color bands on the same items, then it probably is your eyes.

[Kohlrak]

Since your resistors are conveniently in strips, leave them there until you actually need to use one.
All the resistors in the same strip are the same, so measure one without removing it from the strip, then write its value on the paper strip on both sides. You just saved yourself a lot of future measurements or puzzling over color codes.
Repeat for your other strips of resistors.

Too late for some of them, though I think most of them (the ones with the board) didn't come with strips. If they did, i got excited thinking that reading them from colors would be easy.

It's possible you have a red-green color deficiency mild enough it's never been diagnosed. That is the most common form of color-blindness (a misnomer in most cases, as they still see plenty of color). If so, it just means you see some colors less brightly than some people, which can make reds/browns/oranges hard to identify except in really good light. If other people have no problem reading off the color bands on the same items, then it probably is your eyes.

To be honest, the colors when juxtaposed look different, distinctly, but the lighting and such overall makes it rather difficult to tell which color is supposed to be what, even though they are different enough to know that they're different. So, i'm not sure it's actually the eye thing, but incase it is, do you have any images or ways of testing the mildness as opposed to absolute?

A 1.8k resistor (1800 ohms) is brown gray red (18 followed by 2 zeros).

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. Seems I dont' have the 1.8k, I have a 1.5k, so i'm looking for brown green red gold. Oh wait, some of these have more than 4 bands... 

EDIT: nvm, it's 4 bands, it's just weird glare from the lighting in here.

[IanB]

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.

The third band is a multiplier: x0.1, x1, x10, x100, etc.

Therefore 1 ohm is brown black gold (10 x 0.1 = 1).

[Kohlrak]

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.

The third band is a multiplier: x0.1, x1, x10, x100, etc.

Therefore 1 ohm is brown black gold (10 x 0.1 = 1).

Seems more logical to do black brown black, but hey, my job is to read, not to paint them myself. Got one registered 988, definitely looks brown black red. When i changed to 20k, it registered 1.18, so starting when the mode ends with k, i need to add 3 zeros, right? How would it display the 1M ohm and the 10 ohm that are supposedly in here? I assume I go to 2000k, so would it display as 1 and 10 respectively?

[Nusa]

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.

[Kohlrak]

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.

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:

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.

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]

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.

The third band is a multiplier: x0.1, x1, x10, x100, etc.

Therefore 1 ohm is brown black gold (10 x 0.1 = 1).

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]

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.

The third band is a multiplier: x0.1, x1, x10, x100, etc.

Therefore 1 ohm is brown black gold (10 x 0.1 = 1).

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.

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]

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.

The third band is a multiplier: x0.1, x1, x10, x100, etc.

Therefore 1 ohm is brown black gold (10 x 0.1 = 1).

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.

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?

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.