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Electronics => Beginners => Topic started by: cscott242 on April 15, 2023, 01:09:16 am

Title: Mystery Resistor
Post by: cscott242 on April 15, 2023, 01:09:16 am
Can someone tell me the watts of this resistor?
Thank you in advance if you help me.
I don’t know the voltage.
Brown, Black, Red, Black?
Title: Re: Mystery Resistor
Post by: Jwillis on April 15, 2023, 01:44:30 am
Difficult to say without a point of reference to size. Measure the diameter and length of the body. But going by the wire size it looks like 1/4 watt. 
Title: Re: Mystery Resistor
Post by: barshatriplee on April 15, 2023, 11:23:49 am
The size looks like 1W to me.
Title: Re: Mystery Resistor
Post by: Zero999 on April 15, 2023, 11:31:26 am
Without knowing the size, it's impossible to tell. It appears to be made of a ceramic material. so will be able to tolerate a higher temperature, thus more power, than a carbon or metal film resistor of the same size.
Title: Re: Mystery Resistor
Post by: cscott242 on April 15, 2023, 01:07:24 pm
Thank you very much! Here is a more logical pic.
Title: Re: Mystery Resistor
Post by: Zero999 on April 15, 2023, 02:10:20 pm
Thank you very much! Here is a more logical pic.
Visit an electronic component distributor's website.

Go to the section of the site for through hole resistors.

Select axial and the dimensions of the component, about 12mm in this case.

Look at the results.

Here's an example showing Farnell's website.
https://uk.farnell.com/w/c/passive-components/resistors-fixed-value/through-hole-resistors?resistor-case-package=axial-leaded&product-length=12mm

It's probably either 1W, or 2W, depending on whether it's carbon film, or metal oxide/wire wound. Going by your picture, it's probably not carbon film, so the power rating will be 2W. Note that, if you intend to use it anywhere near 2W, then it will get very hot and should be mounted on stand-offs, so as to avoid burning the PCB.
Title: Re: Mystery Resistor
Post by: cscott242 on April 15, 2023, 04:05:26 pm
Wow. Thank you very much. This is amazing that this site exists and you helped me. Thank you
Title: Re: Mystery Resistor
Post by: Gyro on April 15, 2023, 06:41:33 pm
What was the reason for you removing the resistor? Has it gone open circuit? If so, it might be a fusible resistor, designed to open safely to protect against fire under circuit fault conditions. A little background might be helpful.
Title: Re: Mystery Resistor
Post by: Wallace Gasiewicz on April 15, 2023, 08:50:59 pm
Usually fusible resistors have the last band in the color WHITE
Wire wound resistors have the last color BLACK
The exterior construction also suggests a wire wound.
Title: Re: Mystery Resistor
Post by: Gyro on April 15, 2023, 09:13:31 pm
Sure. It's worth checking though, this is the beginners section and we don't have any context to go on.
Title: Re: Mystery Resistor
Post by: Wallace Gasiewicz on April 15, 2023, 09:59:24 pm
Yea, if the resistor is "open" then perhaps chipping away some of the surface would reveal some wire.