SparkFun Forums

[mdaniel2x]

Hi,

I want to make a windshield rain detector in order to trigger car wipers, my question is this : http://www.sparkfun.com/products/8753 can be used in order to detect rain?

Thanks in advance.

[esklar81]

mdaniel2x,

That part appears to be a receiver for an infrared remote control. Did you link to someplace other than you intended? If not, how do you envision using such a device to detect rain?

Eric

[stevech]

Hi,

I want to make a windshield rain detector in order to trigger car wipers, my question is this : http://www.sparkfun.com/products/8753 can be used in order to detect rain?

Thanks in advance.

No, that chip is designed to detect the 38 or 40KHz carrier used in most IR remote controls.

My cars have the rain detector. About all I know is that they have an IR emitter and IR diode/amplifier and signal processor. They have some very complex signal processor to analyze the IR reflections and decide if it's due to water. Not an algorithm I'd like to reinvent.

[fll-freak]

Some older cars (pre ultra fancy electronics) simply had two metalized areas on the outside of the window that interlocked like puzzle pieces but did not touch. When a rain drop bridged the gap, a transistor would start to conduct and trigger the wipers. Very simple as long as a juicy bug did not bridge the sensor!

[marcel0lowrie]

Some older cars (pre ultra fancy electronics) simply had two metalized areas on the outside of the window that interlocked like puzzle pieces but did not touch. When a rain drop bridged the gap, a transistor would start to conduct and trigger the wipers. Very simple as long as a juicy bug did not bridge the sensor!

Seems like if they positioned the "sensor" just above a wiper that problem would solve itself quick. Or maybe use multiple "sensor"'s like that to rule out that scenario's likelihood.

I see no reason OP can do something similar. The IR method seems iffy at best, you would have to know what signal to look for.(correct me if im wrong)

[wholder]

See:

http://en.wikipedia.org/wiki/Rain_senso ... ve_Sensors

and

http://en.wikipedia.org/wiki/Total_inte ... reflection

for some details on how "frustrated internal reflection" is used to detect rain. As the article states "The most common modern rain sensors are based on the principle of total internal reflection: an infrared light is beamed at a 45-degree angle into the windshield from the interior — if the glass is wet, less light makes it back to the sensor, and the wipers turn on. Most vehicles with this feature have an "AUTO" position on the stalk.

This is something you may be able to implement with a modulated IR sender/sensor pair, such as is commonly used for remote controls, to avoid issues with interference from external IR sources.

Wayne

[stevech]

Wayne- thanks. I'm in a debate with my car dealer - the dealer replaced my windshield and now the rain sensor doesn't work. Odd, since they delayed install due to incorrectly ordering a windshield without the mask for the sensor. I hope the replacement isn't somehow reflectively incompatible, if you will.