1
\$\begingroup\$

I have some blown current sense resistor and I don't know how to figure out the value of it. Resistor is blown so I cannot measure it.

Well, I know about standard rules, unfortunately none I know applies to this.
Color bands are quite symmetrically spaced, and the silver band is in the middle.

Colors:
orange (or red?), green, silver, black (thicker), green (thicker)

I assume 1st and 2nd band is for value, 3rd is multiplier, 4th is tolerance and 5th is TCR.

Someone suggested that thicker bands represent tolerance and TCR.
Then it would be 0.35Ω, but black color is not specified for tolerance and green is not specified for TCR.

When I reverse order:
green (thicker), black (thicker), silver, green, orange (or red?)
Then it would be 0.5Ω, ±0.5%, 15ppm

Which one is correct? Or what is the correct procedure and value?

enter image description here

\$\endgroup\$
  • \$\begingroup\$ Can you saw it at the silver band and measure the resistance of the undamaged half? \$\endgroup\$ – Andrew Morton Sep 13 '18 at 17:36
  • \$\begingroup\$ @AndrewMorton Interesting idea. But I did not saw it, but chopped the case (at the blown side) to find the wire. Then I used LCR meter. It shows 0.39Ω. I think this value wont help :( \$\endgroup\$ – Chupacabras Sep 13 '18 at 18:01
  • \$\begingroup\$ Based on the answer saying 0.5, 0.4 is fairly close. \$\endgroup\$ – Passerby Sep 13 '18 at 22:47
  • \$\begingroup\$ @Passerby I measured half of the resistor. Measured resistance doesn't help to identify whether whole resistor is 0.35 ohm (color bands one way) or 0.50 ohm (color bands the other way around). Yes, according to jp-jee's answer it is 0.50 ohm, but it has nothing to do with measured resistance. \$\endgroup\$ – Chupacabras Sep 14 '18 at 5:20
2
\$\begingroup\$

Color code standards are defined in IEC 60062. See also wikipedia: Electronic Color Code

Generally speaking, the first, second [,third] band represent a digit each, followed by a multiplier, tolerance [, temperature coefficient]. Third digit and temperature coefficient are both optional. Given that gold cannot represent a digit (but only multiplier or tolerance), you have:

digit, digit, multiplier, tolerance, temp.coefficient.

Black has no tolerance assigned, which makes it the second digit in your case.

Applying this to your resistor leads to: 5 | 0 | 0.1 | 0.5% | 15ppm/K

Thus, you want a 5 Ohm resistor.

EDIT: It's 0.5 Ohm (multiplier 0.01), given that the middle band is silver (as stated in the question). It looked golden to me, but it's difficult to tell from the picture. However, the above applies to 'silver', where I've referred to 'gold'.

\$\endgroup\$
  • \$\begingroup\$ Are you sure about 0.1 multiplier? Silver is 0.01 \$\endgroup\$ – Chupacabras Sep 13 '18 at 21:19
  • \$\begingroup\$ yes, sure. Silver is 1/100, followed by gold (1/10), black (1), ... you know the rest ;-) \$\endgroup\$ – jp-jee Sep 13 '18 at 21:26
  • 1
    \$\begingroup\$ You have wrong multiplier in your answer then. It should be 0.01 \$\endgroup\$ – Chupacabras Sep 13 '18 at 21:29
  • \$\begingroup\$ Yes, color in the photo looks something between silver and gold. When I look at the resistor with my eyes it definitely is silver, as I mentioned in my question. \$\endgroup\$ – Chupacabras Sep 14 '18 at 5:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.