LED Troubles

Sceadwian said:

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.

Click to expand...

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.

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>

Sceadwian said:

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>

Click to expand...

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.

Roff said:

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.

Click to expand...

Hi Ron,

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

Boncuk

Boncuk said:

Hi Ron,

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

Boncuk

Click to expand...

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