PIR motion detector circuit

A

AK

Guest
I wanted to try this next, but wanted to know if it looks like it has a good chance of working.

https://circuitdigest.com/electronic-circuits/pir-sensor-based-motion-detector-sensor-circuit

Andy
 
On Sun, 19 May 2019 19:19:33 -0700 (PDT), AK
<scientist77017@gmail.com> wrote:

I wanted to try this next, but wanted to know if it looks like it has a good chance of working.

https://circuitdigest.com/electronic-circuits/pir-sensor-based-motion-detector-sensor-circuit

Andy
Click to expand...

All the work is done for you, total of four parts; "working" should
be a slam-dunk. But will it work without a lot of false positives, is
another question entirely.

If, you can tolerate an occasional false positive it will probably
"work." You just have to try different locations and maybe fiddle
around with a baffle to limit the beam width to the area of interest.

I have something like that. Looks identical, and I've had it for
years to turn on a light in a hallway at night. It works well for
that.
 
On Monday, May 20, 2019 at 6:09:53 AM UTC-5, default wrote:
On Sun, 19 May 2019 19:19:33 -0700 (PDT), AK
scientist77017@gmail.com> wrote:

I wanted to try this next, but wanted to know if it looks like it has a good chance of working.

https://circuitdigest.com/electronic-circuits/pir-sensor-based-motion-detector-sensor-circuit

Andy

All the work is done for you, total of four parts; "working" should
be a slam-dunk. But will it work without a lot of false positives, is
another question entirely.

If, you can tolerate an occasional false positive it will probably
"work." You just have to try different locations and maybe fiddle
around with a baffle to limit the beam width to the area of interest.

I have something like that. Looks identical, and I've had it for
years to turn on a light in a hallway at night. It works well for
that.
Click to expand...

Thanks.

Andy
 
On 5/20/19 7:09 AM, default wrote:
On Sun, 19 May 2019 19:19:33 -0700 (PDT), AK
scientist77017@gmail.com> wrote:

I wanted to try this next, but wanted to know if it looks like it has a good chance of working.

https://circuitdigest.com/electronic-circuits/pir-sensor-based-motion-detector-sensor-circuit

Andy

All the work is done for you, total of four parts; "working" should
be a slam-dunk. But will it work without a lot of false positives, is
another question entirely.

If, you can tolerate an occasional false positive it will probably
"work." You just have to try different locations and maybe fiddle
around with a baffle to limit the beam width to the area of interest.

I have something like that. Looks identical, and I've had it for
years to turn on a light in a hallway at night. It works well for
that.

The problem is mostly with PIRs mounted on the house in the winter.
Click to expand...

Like other thermal detectors, the PIR measures its own temperature, and
not that of the scene. In fact, because of the load resistor across the
pyroelectric element, it actually measures a highpass-filtered (AC)
version of its temperature.

When it's cold outside, the PIR's temperature is higher than ambient
because of thermal conduction from the house via the mounting. A quick
gust of wind will cool the sensor, which looks just the same as the
ambient warming up.

Cranking the sensitivity down a bit helps, as does a more intelligent AC
detection system than just a threshold.

Cheers

Phil Hobbs



--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Mon, 20 May 2019 13:56:49 -0400, Phil Hobbs wrote:

When it's cold outside, the PIR's temperature is higher than ambient
because of thermal conduction from the house via the mounting. A quick
gust of wind will cool the sensor, which looks just the same as the
ambient warming up.
Click to expand...

The problem is trying to use PIRs outside - period.



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.
 
On 5/21/19 1:41 PM, Cursitor Doom wrote:
On Mon, 20 May 2019 13:56:49 -0400, Phil Hobbs wrote:

When it's cold outside, the PIR's temperature is higher than ambient
because of thermal conduction from the house via the mounting. A quick
gust of wind will cool the sensor, which looks just the same as the
ambient warming up.

The problem is trying to use PIRs outside - period.
Click to expand...
Dunno. I've used them outdoors without issues, as long as they're
sheltered from the wind in the winter and the sensitivity isn't cranked
up too high.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net
 
On Tue, 21 May 2019 16:20:26 -0400, Phil Hobbs wrote:

Dunno. I've used them outdoors without issues, as long as they're
sheltered from the wind in the winter and the sensitivity isn't cranked
up too high.
Click to expand...

Perhaps if they were hooded all round they'd become usable. I've never
tried it; might be worth a shot.



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.
 
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