LED Troubles

[Roff]

I'm gonna side with audioguru at this point, it may just have been a tiny spot that was heating. Even if it was only 1/10th the area of the resistor that was getting hot your finger would think the whole thing was. Human perception is a HORRIBLE method of measuring temperature, because it can be easily fooled and it's relative not absolute. I bought an IR non-contact thermometer for these kinds of things, I found out though that such a small target as a resistor doesn't read properly =( Works great on mosfets or larger packages though.

I tried to use my Shady Ol' Rack non-contact thermometer on the resistor I tested. As you said, the target is too small. My upper lip works well, although it is uncalibrated.

 

[Sceadwian]

Just make sure you hover before touching Roff =) If you can feel the heat before contact, it's usually not a good idea to proceed =\ I use my lip too, veerrryy sensitive. Fingers are a bad idea, if it's too hot you've lost heat sensors (and probably skin cells) before you even pull away, too much distance from the sensor to the brain =) Clasic electrical problem. Just in the human body <smirk>

 

[Roff]

Just make sure you hover before touching Roff =) If you can feel the heat before contact, it's usually not a good idea to proceed =\ I use my lip too, veerrryy sensitive. Fingers are a bad idea, if it's too hot you've lost heat sensors (and probably skin cells) before you even pull away, too much distance from the sensor to the brain =) Clasic electrical problem. Just in the human body <smirk>

After having a red "D" burned into my index finger tip by a very hot TO-92, I learned not to test by touching unless it is just a tap (I was about 22 years old - I'm now 68). The lip can detect high heat from several cm. Very handy for seeing if your soldering iron is on.
In this case, I went through several phases of heat testing, ending with the resistor contacting my lip.

EDIT; Off-topic, but have you noticed that when a rubber band is stretched, it emits heat (which isn't surprising), but it absorbs heat when it relaxes. This surprised me when I discovered it with my lip many years ago.

 

[Boncuk]

Maybe to a German in Thailand.

I'm just giving you a bad time.

I had to read his post 2 or 3 times before I was sure he was talking about the resistors.

Hi Ron,

you might want to google for this: "Was kümmert es eine deutsche Eiche, wenn sich ein Wildschwein daran reibt?"

Boncuk

 

[Roff]

Hi Ron,

you might want to google for this: "Was kümmert es eine deutsche Eiche, wenn sich ein Wildschwein daran reibt?"

Boncuk

Did you try what you suggested? The sentence doesn't appear verbatim in any search result.