On 5/8/2017 7:24 PM, rickman wrote:
On 5/8/2017 8:19 PM, mike wrote:

If I pass my 12:1 IR temperature probe across the resistor, the highest
reading I
can get is 71F if I stick it as close as possible to the resistor.
You really need the area being sensed to fill the whole field
of view of the sensor. Pretty much useless for today's electronics.

You can restrict the field of view with a straw. I haven't calibrated
this approach, but it should work ok. The sensor element is very small
and is at the base of a black cone which I believe is what establishes
the field of view. As long as you are viewing hot items it shouldn't
matter that the straw is not as black as the cone. Maybe I'll try this
later if I can find my IR thermometer.

Yes, that does work. It won't be accurate temperature, but you can tell
relative temps if they're much hotter than ambient.
Unless your straw is surrounded by a really good IR blocker, the
radiation from the blockage might swamp the changes from the straw.

I once experimented with a PIR sensor attached to a an LED.
I put a straw over the sensor to restrict the field of view.
My expectation was that I could scan an area watching the LED
and have my brain construct a rough image of what I was scanning.
Alas, my brain was not up to the task.
Then, I decided to rotate the assembly to scan a line and correct
for angle and distance and put dots on the screen of my PDA
according to position of the spinner and tilt of the whole
assembly for the Y axis.
Alas, my brain wasn't up to that task either.