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Homemade Infrared Rangefinder (Similar to Sharp GP2D120

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Here is my instructable on how to construct a pretty simple (for some!) short range infrared rangefinder/range sensor. Infrared rangefinders are very useful in a number of projects. The majority of these come from obstacle detection (in robots) or generally detecting distances! The one shown here is only a simple rangefinder and will only really be able to measure about 6 or 7cm infront of the range finder. Luckily, most objects reflect infrared well enough to produce a reading (including a hand, paper and tin foil). I will be showing you how to use the infrared range finder with an Arduino and ways of linearizing the result.
 
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Step 1: Theory

The theory behind an infrared rangefinder is that pulsed infrared is emitted from an IR led and then reflected back off an object into an IR receiver. As light adheres to the inverse square law which states that as distance from a source is increased, the intensity decreases by the square (Source: http://hyperphysics.phy-astr.gsu.edu/hbase/vision/isql.html). Essentially, the light is emitted by the infrared LED, which then bounces off the object. In the first instance, the LED is the emitter and the reflective object is the observer. Once the light hits the object, it then bounces off and is reflected back to the IR receiver. The object is then acting as the source of light so the inverse square law takes effect twice. This has the problem that the maximum range of the rangefinder is quite short and to increase the range, higher power LED’s would be required.

Another problem that takes affect with light based rangefinders is how it can be affected by ambient light. I fix this in my rangefinder by modulating the emitting LED. Without this modulation, a simple light bulb connected to the mains can affect the result by superimposing 50Hz onto the actual signal.

My rangefinder works through having a  modulated IR source at an ultrasonic frequency, being detected by a IR receiver (IR photodiode) which is then fed into a high pass filter, amplified and peak detected.
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Mic10010 months ago
I finally built your 36KHz version of the NE555 everything is OK thank you
Now I will look for RC5
everything is here smd pictures of test
http://sdrv.ms/QCZ8j1


pyrohaz (author)  Mic1005 months ago

Awesome pcb man! Glad it worked for you :)

This is so great!

motherprune1 month ago

This is so great!

Its fascinating

mousepaper1 month ago

Thats really good

Really good

amazedgreen1 month ago

awesome.

fastbobble1 month ago

Thats wonderful...

gorgeddamp1 month ago


Thats awesome...

Its astounding

illrings1 month ago


Thats fabulous

airbugger2 months ago

Thats fascinating


Its helpful :)

headlymph2 months ago

good

tealrink2 months ago

NICE

grousebandit2 months ago




Thats grand

harechubby2 months ago

good

clapfilk3 months ago

good

cheshirecorn3 months ago

Thats incredible

good

workexaminer3 months ago


Thats spectacular...

HWgeek4 months ago

Very nicely done! Having had to deal with Sharp this looks like a nice way to not have to use their stuff.

Question on Step 3 - probing the IR receiver - the scope trace. What point were you probing and what was your voltage scale on the scope?? I ask, as I am trying my hand at building up this circuit, having some issues with getting it working on the receiving end. The darlington pair doesn't seem to be amplifying the signal. Thanks!

gazumpglue5 months ago

her is the kicad PCB projet in zipped file in my i've remplaced the 4148

diodes by shottky diodes

Mic1005 months ago

thanks to :)

her is the kicad PCB projet in zipped file in my i've remplaced the 4148

diodes by shottky diodes

http://sdrv.ms/1aJznbw

pyrohaz (author)  Mic1005 months ago

Them 3d plots are great! Is that a part of kicad? I'm still used to working with eagle haha

Mic100 pyrohaz5 months ago

yes is part of kicad

pyrohaz (author)  tiecheap5 months ago

Cheers! :)

pyrohaz (author)  gamystuffed5 months ago

Thank you!

pyrohaz (author)  craniumfurbelow5 months ago

Thanks :)

pyrohaz (author)  nativemedia5 months ago

Cheers! :)

vandhika9 months ago
im newbie to electronics and want to learn. this project suites me as it seems easy to be done and i need distance meter that can be logged.

if build this, do i need the oscilloscope? is all component typical so i can use your constant (Normalize_constant, etc)?
pyrohaz (author)  vandhika9 months ago
Hey, you don't need an oscilloscope to do this project at all fortunately though one would definitely help to debug it. With hope, if you follow the build instructions directly, it should fully work! All of the component values will work with the current values.
BunnyRoger10 months ago
Very good Instructable!!!
pyrohaz (author)  BunnyRoger10 months ago
Cheers!
Amanda Culbert10 months ago
Awesome instructable!!
pyrohaz (author)  Amanda Culbert10 months ago
Thank you :D
MAApleton10 months ago
Very cool. Definitely one of my favorites.
pyrohaz (author)  MAApleton10 months ago
Thanks a bunch!
My Diet Area11 months ago
Thats fabulous...
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