help with passive and active IR

[Joe]

Awhile back, I built a passive IR system to take pictures. I built it by the
plans on www.jesseshuntingpage.com in his section on homebrew trail
cameras.

When I use it in a small area, with a solid backdrop it works OK, but if I
try to 'watch' a trail, I am getting a lot of false triggers. Presumably
from air currents, and possibly leaves, grass, and tree limbs moving side
to side in the wind.

I was thinking of using the passive system to turn on another, active
system. I have a laser pointer that I took apart and could modulate, but I
would rather have the light be invisible. The passive system I use now turns
on a relay which trips the camera shutter. I would like it to turn on
another IR LED which would shoot a beam into the target area and if the beam
gets reflected (by something which has moved into the target area), I could
trip the shutter and take the picture.

The problem is, I am not sure how to detect the reflection of the IR beam
(or laser). This is a battery powered device, so I wouldn't want the active
portion of the detector 'on' all the time. I would also like to be able to
use this day or night. Any help is appreciated.

TIA,
Joe

 

[John Popelish]

Joe wrote:

Awhile back, I built a passive IR system to take pictures. I built it by the
plans on www.jesseshuntingpage.com in his section on homebrew trail
cameras.

I'll be darned if I could find any reference to home-brew trail
cameras on this page. Can you give a better url?

When I use it in a small area, with a solid backdrop it works OK, but if I
try to 'watch' a trail, I am getting a lot of false triggers. Presumably
from air currents, and possibly leaves, grass, and tree limbs moving side
to side in the wind.

I was thinking of using the passive system to turn on another, active
system. I have a laser pointer that I took apart and could modulate, but I
would rather have the light be invisible. The passive system I use now turns
on a relay which trips the camera shutter. I would like it to turn on
another IR LED which would shoot a beam into the target area and if the beam
gets reflected (by something which has moved into the target area), I could
trip the shutter and take the picture.

The problem is, I am not sure how to detect the reflection of the IR beam
(or laser). This is a battery powered device, so I wouldn't want the active
portion of the detector 'on' all the time. I would also like to be able to
use this day or night. Any help is appreciated.

Before you discard what you have and start over, it might be possible
to improve what you have. But I can't find it to discuss that.

--
John Popelish

 

[Joe]

"John Popelish" <jpopelish@rica.net> wrote in message
news:3F627F79.32ABE7DF@rica.net...

Joe wrote:

Awhile back, I built a passive IR system to take pictures. I built it by
the
plans on www.jesseshuntingpage.com in his section on homebrew trail
cameras.

I'll be darned if I could find any reference to home-brew trail
cameras on this page. Can you give a better url?

When I use it in a small area, with a solid backdrop it works OK, but if
I
try to 'watch' a trail, I am getting a lot of false triggers. Presumably
from air currents, and possibly leaves, grass, and tree limbs moving
side
to side in the wind.

I was thinking of using the passive system to turn on another, active
system. I have a laser pointer that I took apart and could modulate, but
I
would rather have the light be invisible. The passive system I use now
turns
on a relay which trips the camera shutter. I would like it to turn on
another IR LED which would shoot a beam into the target area and if the
beam
gets reflected (by something which has moved into the target area), I
could
trip the shutter and take the picture.

The problem is, I am not sure how to detect the reflection of the IR
beam
(or laser). This is a battery powered device, so I wouldn't want the
active
portion of the detector 'on' all the time. I would also like to be able
to
use this day or night. Any help is appreciated.

Before you discard what you have and start over, it might be possible
to improve what you have. But I can't find it to discuss that.

--
John Popelish

Hi John,
My apologies, he has changed his page drastically since the last time I
visited it. Here is a url direct to the PIR page.

http://www.jesseshuntingpage.com/regent-ms20.html

I was not planning on discarding the system I have. I just thought that
adding an active sensor to it may decrease the number of false triggers.

Joe

 

John Popelish <jpopelish@rica.net> wrote:

Joe wrote:

Awhile back, I built a passive IR system to take pictures. I built it
by the
plans on www.jesseshuntingpage.com in his section on homebrew trail
cameras.

I'll be darned if I could find any reference to home-brew trail
cameras on this page. Can you give a better url?

When I use it in a small area, with a solid backdrop it works OK, but
if I
try to 'watch' a trail, I am getting a lot of false triggers. Presumably
from air currents, and possibly leaves, grass, and tree limbs moving
side
to side in the wind.

I was thinking of using the passive system to turn on another, active
system. I have a laser pointer that I took apart and could modulate, but
I
would rather have the light be invisible. The passive system I use now
turns
on a relay which trips the camera shutter. I would like it to turn on
another IR LED which would shoot a beam into the target area and if the
beam
gets reflected (by something which has moved into the target area), I
could
trip the shutter and take the picture.

The problem is, I am not sure how to detect the reflection of the IR beam
(or laser). This is a battery powered device, so I wouldn't want the active
portion of the detector 'on' all the time. I would also like to be able
to
use this day or night. Any help is appreciated.

Before you discard what you have and start over, it might be possible
to improve what you have. But I can't find it to discuss that.

--
John Popelish

Hi Joe

The field of view for the IR sensor is about 110 degrees.
If you limit the field of view by putting some black tubing on the front
of the sensor it might reduce the false triggering.

Colin G


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[Colubris]

"Joe" <nuisancewildlife@nospamearthlink.net> wrote in message news:<gPu8b.5145$NM1.3329@newsread2.news.atl.earthlink.net>...

Awhile back, I built a passive IR system to take pictures. I built it by the
plans on www.jesseshuntingpage.com in his section on homebrew trail
cameras.

When I use it in a small area, with a solid backdrop it works OK, but if I
try to 'watch' a trail, I am getting a lot of false triggers. Presumably
from air currents, and possibly leaves, grass, and tree limbs moving side
to side in the wind.
SNIP
TIA,
Joe

Hi Joe,
If you check out the forums and other cam-related pages at that site,
you'll find tons of info about the "falsing" problem and how to reduce
it to reasonable levels.
I've built the Passive/Active system as you describe, and while it's
not difficult, I just about never use it in favor of the regular
passive systems.
BTW - the active sensor in this application does not detect a
reflection from the target, but creates a "beam" which the target
breaks by walking through it.
Sometimes called "break-beam" detectors.

Arch

 

[Joe]

<1042241977@127.0.0.1:7501> wrote in message
news:3f62b97a$1_1@news.Usenet.com...

Hi Joe

The field of view for the IR sensor is about 110 degrees.
If you limit the field of view by putting some black tubing on the front
of the sensor it might reduce the false triggering.

Colin G

Thanks for the info Colin. I have been using tape to reduce the field of
view. I was thinking I would be needing something to 'confirm' that
something was actually in front of the sensor before wasting a photo, hence
the 'dual system' idea. I was surprised by all the new stuff on jesses
site, so I am going to go back and check it out. Maybe he already has
something there.
Thanks again for the info.

Joe


Joe

 

[Joe]

"Colubris" <archilochus57@yahoo.com> wrote in message
news:b42cfb8e.0309130607.45499eef@posting.google.com...

Hi Joe,
If you check out the forums and other cam-related pages at that site,
you'll find tons of info about the "falsing" problem and how to reduce
it to reasonable levels.
I've built the Passive/Active system as you describe, and while it's
not difficult, I just about never use it in favor of the regular
passive systems.
BTW - the active sensor in this application does not detect a
reflection from the target, but creates a "beam" which the target
breaks by walking through it.
Sometimes called "break-beam" detectors.

Arch

Hi Arch,

thanks for the info. I was surprised by some of the new stuff that's out
there now so I will be checking closer to see how to minimize false
triggering.

On the subject of break beam detectors. I thought that to build one you
needed a 'transmitter' at point A and the receiver at point B. After
properly aligning them (ugh!) then when a target breaks the beam, you can
energize a relay, or turn on a transistor. I wanted to stay away from such a
system and try to have the transmitter and receiver in the same box, aimed
at the center of the field of view. Then when the PIR detects something,
turn on the active transmitter for 5 or 10 seconds (to give the target time
to get into the center of the field of view), and when the receiver detects
the reflection, it triggers the camera shutter. I was thinking of (of all
things), how a laser guided munition finds its target. It homes in on the
reflected laser beam that is directed at the target either by the launch
aircraft or by troops on the ground. The target is 'painted' and the
munition just homes in on the reflection. I guess active radar guided
munitions work the same way.

Maybe something like that would be more grief then it is worth. I thought it
would be fun to build and see how it worked anyway.

Thank you again for the info,

Joe

 

[Colubris]

Hi Arch,

thanks for the info. I was surprised by some of the new stuff that's out
there now so I will be checking closer to see how to minimize false
triggering.

On the subject of break beam detectors. I thought that to build one you
needed a 'transmitter' at point A and the receiver at point B. After
properly aligning them (ugh!) then when a target breaks the beam, you can
energize a relay, or turn on a transistor. I wanted to stay away from such a
system and try to have the transmitter and receiver in the same box, aimed
at the center of the field of view. Then when the PIR detects something,
turn on the active transmitter for 5 or 10 seconds (to give the target time
to get into the center of the field of view), and when the receiver detects
the reflection, it triggers the camera shutter. I was thinking of (of all
things), how a laser guided munition finds its target. It homes in on the
reflected laser beam that is directed at the target either by the launch
aircraft or by troops on the ground. The target is 'painted' and the
munition just homes in on the reflection. I guess active radar guided
munitions work the same way.

Maybe something like that would be more grief then it is worth. I thought it
would be fun to build and see how it worked anyway.

Thank you again for the info,

Joe
Hi Joe,

The break-beam detectors work just as you described. You can also use
a reflector at "point B" instead of a receiver. The mirror reflects
the "beam" back at the transmitter unit - which also has the receiver
in it. That way all the electronics are in one case. Sometimes called
a "retro-reflective break-beam detector". The alignment is still a
pain - which is one of the main reasons I don't use the setup anymore.
You also tend to miss a lot, because the active is so precise.

I don't think you could expect to get an active IR signal to reliably
reflect off of a passing animal at a reasonable range with an
affordable home-brewed circuit. Maybe one of the pro's here can come
up with an idea for that.

There's also the possibility of using a microwave or ultrasonic
detector that gets activated by the passive. Achieve the same results
without the drawbacks of the active IR setup.

Arch

 

[Joe]

"Colubris" <archilochus57@yahoo.com> wrote in message
news:b42cfb8e.0309141527.785178ab@posting.google.com...

Hi Joe,
The break-beam detectors work just as you described. You can also use
a reflector at "point B" instead of a receiver. The mirror reflects
the "beam" back at the transmitter unit - which also has the receiver
in it. That way all the electronics are in one case. Sometimes called
a "retro-reflective break-beam detector". The alignment is still a
pain - which is one of the main reasons I don't use the setup anymore.
You also tend to miss a lot, because the active is so precise.

I don't think you could expect to get an active IR signal to reliably
reflect off of a passing animal at a reasonable range with an
affordable home-brewed circuit. Maybe one of the pro's here can come
up with an idea for that.

There's also the possibility of using a microwave or ultrasonic
detector that gets activated by the passive. Achieve the same results
without the drawbacks of the active IR setup.

Arch

Hi Arch,

I didn't think about a reflector for the break beam. Still a pain to align
tho. If IR is not good, what about laser? I have a laser pointer I took
apart and I can pulse it. The problem is that it would be visible, but
possibly more reliable then active IR? I don't really need a 60 ft range for
the PIR . What I do for my regular business is evict or sometimes trap and
remove nuisance wild animals from peoples attics, sheds, crawlspaces, etc. I
use the trailcam setup so I can show a picture to the client of whatever is
causing them the grief if they don't already know what animal it is. It also
comes in handy doing evictions where I have proof that the animal is gone
(by the lack of activity) once I do what I have to in order to make them
move. The ranges I am working at are usually under 30 feet. Most times, the
trailcam is within 20 feet of the den.

I don't know if I want to play around with microwave (I guess that would be
a radar of sorts), but ultrasonic may be ok. I'll do a google search on it
and see what I can find.

Thanks again,
Joe