MS20 Out of Its case

Canuck

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I have been trying to mount the MS20 board in my gamecamera housing with the fresnal lens mounted directly to the box.  I have mounted it everywhere from 7/8 to 1 1/4 inches from the sensor and at every distance I seem to be loosing most of the sensors sensitivity.  Even at the recommended distance of 1 1/16 inches the sensitivity of the sensor is dropping from 45' to 8-10'.  Anyone have any suggestion on what could be causing this.  If I put the sensor back toghether the sensitivity returns to normal.  I have tried this on the last two units I have modified.

MS20, modified with Jons low power suggestions, fresnal mounted flat, correct side out, 9V supply.
 

Archilochus

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Hi Canuk,
Lens alignment - both horizontal and vertical - is very important too!  Particularly with the MS-20 type Fesnel lenses that have assorted lens segments with varying ranges.  Some Fresnel lenses have little crosses pressed into the plastic along the outer edges that will show the ideal center point of the lens.

Archilochus
 

davered1

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Those MS20 lenses are divided into 28 or so different sections, make sure when you paste the lens in place you position PIR just above the split line in the middle of the lens the little stubby sections look down the long skinny sections look out straight.

In a 1" hole I run the stubby sections about 1/4 way up the rest is filled with the skinny sections. Also pir has to be centered in hole as well
 

Canuck

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Thanks for the suggestions.  By moving the lens up so the stubby sections were 1/4 into the hole I was able to extend the sensor range back to normal.  Never had that problem with the radio shack sensor.  Thanks again...
 

wfontjr

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could we use a clear piece of the fresnal lense, (that is no scoring) to cover up the hole in the case and leave the original fresnal lense mounted in the ms20 head, is the sensor able to see thru two of these lenses? anybody have an idea for a source? anybody try something like this yet?
 

Archilochus

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Hi wfontjr,
That's what I did on a trail-cam with an RS 49-425 that I built for a friend.

http://www.geocities.com/archilochus57/49-425.html

See the link "outside view"

The material is "raw" PolyIR4 from Fresnel Technologies
< http://www.fresneltech.com >

This technique works well in that you have no alignment / spacing problems with the Fresnel lens.
You can also use multiple layers of the material to get a "no electronics" sensitivity adjustment.  The material transmits about 80% of the "good" IR signal - so each layer added will cut down a bit on overall sensitivity.

Archilochus
 

wfontjr

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i vaguely remembered something like this, but i could not recall if it got tried or was successful, thanks for the help, well here goes another order
 

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