Topic: Resistor color codes

[miraculon]

I just received a small bench power supply from MPJA (Marlin P Jones) and inside the box was a nice resistor (resister) color code card. Since the color codes seem to be a problem area on building of RED kits, I thought that I would post the information below.

Not sure how to get one other than ordering something, but there was an article explaining the resistor codes and how to read them. I plan on keeping my card at my bench for future reference. I suppose you could print it out and laminate it and get the same result, more or less.



https://www.mpja.com/how-to-read-resisters.asp

Greg H.

[corwyyn]

Nice!  I may just do what you suggested That's the main reason I'm doing my 3D model for images - to make it that much easier for folks to see which components go where, especially the resistors, ceramic capacitors and inductors.

[Einar]

The problem is usually not the colors. Those color Charts are easy to find.

It seems the problems are deciding what colors the bands actually are. I find that a problem in some cases even after handling resistors for >40 years. 1,2,3 and 7 are not always that easy to tell apart. Obviously the producers do not use the same pail of Paint. Some are easy to read, others are not.

The other problem you may face is that the % band is not very well separated from the others. It was easy way back when most were 5% (gold). But now they are 1% and you have a bit more trouble to decide from what direction to read them. Usually Reading from the wrong end will indicate a value not in the E24 series and then you try from the other end.

For anyone stuffing resistors a VOM is well Worth its price. You don't need a NIST calibrated instrument. The cheap ones will do fine. If in any doubt, measure the resistor.

[DanS]

I just received a small bench power supply from MPJA (Marlin P Jones) and inside the box was a nice resistor (resister) color code card. Since the color codes seem to be a problem area on building of RED kits, I thought that I would post the information below.

Not sure how to get one other than ordering something, but there was an article explaining the resistor codes and how to read them. I plan on keeping my card at my bench for future reference. I suppose you could print it out and laminate it and get the same result, more or less.



https://www.mpja.com/how-to-read-resisters.asp

Greg H.

Another chart that helps (me anyway) is the capacitor numbering chart. I have no problem reading caps stamped with values like .2uf etc. but when they put numbers like 254 on it only then I have to look at a chart. The old school I grew up with taught us the resistor color code (bad boys rape our young girls ..) and capacitor values were printed on them or color coded at least.

[wxtech]

The capacitor numbers are easy to interpret.  The right most digit is the number of zeros to add to the first two significant digits.
The 254 would then be written as 250000.  (25 & 4 zeros)  This is the value in picofarad, pf.  Now put the decimal point 6 places to the left for microfarad.  This gives the value of .25 uf.

103 would translate to .01 uf  This value numbering system is also used on high quality resistors with printed numbers.  1004 on a resistor is 1 meg. 1000 = 100 Ohms

On component values, R is the radix point, the decimal point.  1R5 = 1.5

50 years of reading electronic color codes, and the resistance numbers appear instantly.  My poor eye sight makes reading the tiny numbers difficult.  I take several resistors with numbers to the Ophthalmogist to show the tiny numbers that he/she needs to help me read.

[JonathanW]

The problem is usually not the colors. Those color Charts are easy to find.

It seems the problems are deciding what colors the bands actually are. I find that a problem in some cases even after handling resistors for >40 years. 1,2,3 and 7 are not always that easy to tell apart. Obviously the producers do not use the same pail of Paint. Some are easy to read, others are not.

The other problem you may face is that the % band is not very well separated from the others. It was easy way back when most were 5% (gold). But now they are 1% and you have a bit more trouble to decide from what direction to read them. Usually Reading from the wrong end will indicate a value not in the E24 series and then you try from the other end.

For anyone stuffing resistors a VOM is well Worth its price. You don't need a NIST calibrated instrument. The cheap ones will do fine. If in any doubt, measure the resistor.

I agree with this.  I test every resistor (and now capacitor and inductor, with an LCR meter) before using it.  I know the color codes by heart, but testing takes the guesswork out of things (as well as very human mistakes).

That said, the chart is nice