View Full Version : Sheilding photo resistors
02-10-2007, 12:49 AM
I am using three photo resistors to make my robot roam towards a light and was wondering
if anyone had an idea what I could to use to shield them from normal room light. I want to
shield them seperate from each other and the normal room light.
02-10-2007, 12:54 AM
Black Heat-shrink tubing comes in several diameters, and is quite an effective light-blocker.
You might have to 'paint' the rear of the photo-resistor with black nail-polish to block light from the rear.
And black electrical tape also can work, though that's much less permanent.
02-10-2007, 12:57 AM
Any kind of metal tubing large enough to insert a photo resistor would do. The length of the tube would determine the "viewing angle". Many hobby stores have short lengths of aluminum tubing that can be easily cut with a fine hacksaw. You need to insulate the edges of the photo resistor with electrical tape, possibly by lining the end of the tube with some. A blob of opaque (black) silicone rubber would hold everything in place and block light from coming in the end of the tube. Obviously test it before you seal it up.
You could use plastic tubing as well, but some plastic tubing that appears opaque is not completely so, particularly to infrared. Check first.
Combinations, like of clear plastic tubing with electrical tape on the outside or black shrink wrap tubing on the outside could also work.
02-10-2007, 01:15 AM
Yeah I was thinking about a piece of plastic tube I had. However the tube is white, so I figured I put some electrical
tape on it.
02-14-2007, 04:08 AM
I had really good luck with black straws from Harvey's Fast Food Joints. Not sure if they exist in the US.
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