Introduction: Resistor Color Code Guide

Picture of Resistor Color Code Guide

This guide shows an easy illustration on using resistor color codes.  The image is fairly easy to understand up front, but I will provide some explanation.

There are typically between 4 bans and 6 bands on a resistor.  You must be very careful when reading them because after a long day working some colors can start to blend.

The first 2-3 bands represent single digits, there will then be a band representing the multiplier, a space, and then a tolerance band.  On some occasions there will be a temperature coefficient band at the end.

The easiest way to learn to read it is to imagine writing the numbers down on paper

for example, say we have a resistor with the following colored bands : BROWN, GREEN, RED, GOLD

This would represent the following:

BROWN   -   GREEN   -   RED   -   GOLD
       1                    5            X100        +/-5%

so it is simply 15 x 100 +/- 5%

so you would be holding a 1500 ohm resistor with a 5% tolerance (meaning the resistor value can actually be anywhere between 1425 and 1575)

And thats it, pretty simply to pick up, i wouldnt worry about memorizing the colors, You get used to them after a while but i always have a card nearby with the color codes on them too.

Photo credit :


WallyB1955 made it! (author)2016-08-11


I have a shaver I bought back in 1973. It is a very simple design and a classic.

The main and only resistor broke in half and I need to replace it.

The problem is: From the heat and age the color bands are darkened to where I can not make out the color of the bands to determine the resistor rating.

Can you please take a look and see what you think the rating of that one large resistor is so I can then get and replace it (Your best guess would be appreciated).

The company that made the saver is WAHL and the Model number is 7300.

I contacted the company's engineering department but they no longer have the schematics for that model to look up the rating of that resistor, so no help there.

If you can tell exactly what the rating is from the attached picture, then Great! Or again, your best guess would be appreciated!

A look at the diode on the other side may help towards determining the rating of that large resistor. I love the design of this old shaver so restoration is a must for me to do.

The company did have the two carbon brushes from a newer model, sent them to me and I replaced them. The resistor they did not have and it is the last item I need to replace to get this classic back up and running.



BooRan (author)WallyB19552016-08-12

It looks larger, so it's probably at least a 1/2 watt, maybe even a 1 watt resistor. I can make out a darker stripe and a gold stripe, so first value is probably black (0) or brown (1) and its probably a +- 5% tolerance. I can't make out any stripes in the middle so we still need the multiplier number. I can't find any references to a WAHL 7300 online. Are you sure that is the model number? Is there any more information or pictures you can share about it?


WallyB1955 (author)BooRan2016-08-17

I soaked the resister in a combination of CLR / Bleach / Hydrogen Peroxide for a few hours to see if it would clean up enough to see any portion of the inside bands.

Well, per the "four" bands on the resistor what I could identify was: #1-Red, #2-Red, #3, (maybe Blue or Black), #4-Gold

Based on the item, a shaver, 115V coming in, going through one diode, and the voltage held at 35V (based on the patent specs), what is your best guess now as to the rating of that resistor?



WallyB1955 (author)BooRan2016-08-12

Yes, (correction) it is a Model 9700 as shown in the cast molding of the shaver.

It is a very old model and that was why WAHL had no specs on it (that model went back to the 60's) It came in a kit that was noted as kit # 9743

On the inside of the back casing it had a US Patent Pending # 2795967 & 2789347 & 2876538 which on a search of the USPTO did not show the motor.

Did come across this one filed by WAHL in 1970 that sowed the motor:

But it did not show ratings of the resistor. It did note the Diode kept the voltage to 30V

I took a close-up picture of the Resistor and it is attached

Kent JudeB (author)2016-08-02

Thanks for this :D It helps me a lot ...

Mase13 (author)2015-07-03

thank you for explaining that it helped a lot

Dardaro (author)2013-03-02

thanks was still stuck in the 4-band

About This Instructable




Bio: Electrical Engineer, control systems, automation, small electronics, home automation, microcontrollers etc.
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