Ultrasonic or IR sensor module

Thread Starter

tomcat_meow

Joined Jan 5, 2012
15
I am designing an outdoor vending machine that I need to detect if there is product available for sale in a cell approx 2ft. x 2ft. x 2ft. I'm looking for the best way to detect product . Temperature ratings on this machine could go as low as -40C and as high as 80C depending on where it is located in the world. I have been searching for a cost effective solution of either ultrasonic or IR type sensor module that can operate in this temp range. I need 8 of these sensors per machine hence the cost effectiveness becomes very important. A module that can be coded into an embedded controller is what I'm seeking. Anyone have any experience with these devices?
 

jpanhalt

Joined Jan 18, 2008
11,088
Typical IR receivers are spec'd at down -30°C. That doesn't mean they won't work at -40°C. What examples did you find spec'd to -40°C?
 

Thread Starter

tomcat_meow

Joined Jan 5, 2012
15
I haven't found any spec'd lower than -20 so far. The cheap ones typically used by experimenters with say an Arduino are spec'd at -10 and they do stop right about there.
 

djsfantasi

Joined Apr 11, 2010
7,922
Just a thought. Does your outdoor vending machine have any display lighting?

If so, use a a bulb as a heater to keep the sensors above its minimum operating temperature. Some engineering will be necessary to isolate the bulb and sensor.

Along the same lines, you may be able use a resistor or resistors as a heater. I’ve seen this technique used to stabilize a clock.

Basically, somehow heat the interior. Either locally (to the sensor) or generally (to the interior)
 
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