# motion sensor for daylight use

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#### MrDEB

##### Well-Known Member
Is there such a device that is relativity cheap but laser is to dangerous for application intended.
Most sensors use IR which during daylight use is perhaps worthless.
Thinking about IR but using a pulsed signal applied to the IR. This needs to cover a radius of 8-10 feet.
Still researching but any suggestions might steer in right direction.

#### Nigel Goodwin

##### Super Moderator
Is there such a device that is relativity cheap but laser is to dangerous for application intended.
Most sensors use IR which during daylight use is perhaps worthless.
Thinking about IR but using a pulsed signal applied to the IR. This needs to cover a radius of 8-10 feet.
Still researching but any suggestions might steer in right direction.
I suspect you're somewhat confused about PIR (Passive Infra Red) sensors?.

They work perfectly well in the day time, as they simply look for a moving heat source (i.e. a body - or dog, or cat.......).

In fact they work so well in the day that they have to used in conjunction with light sensors, to disable them during the day (as they are usually used for night time lighting).

Another (more expensive) would be microwave radar, as commonly used for automatic doors in shops.

I fail to see why you think a laser would be 'dangerous'?, as only high power ones have the slightest 'danger' about them, and you could easily make a broken beam detector (if that do) using a simple IR LED and detector.

But what are you trying to detect, and where?.

#### Diver300

##### Well-Known Member
PIR sensors are used for burglar alarms. They work fine in daylight, and won't have light sensors to disable them during the day.

#### MrDEB

##### Well-Known Member
Well maybe I am confused about sensors.
I want to detect movement in a vehicle like a child left in a car seat or a pet.

#### Nigel Goodwin

##### Super Moderator
A PIR should do that fine then.

#### MrDEB

##### Well-Known Member
I have several but when I tried them on a deer repelent device I built the sensor never shut the device off. Regardless of movement etc. Worked ok in dark.
Need to investigate further.

#### Nigel Goodwin

##### Super Moderator
I have several but when I tried them on a deer repelent device I built the sensor never shut the device off. Regardless of movement etc. Worked ok in dark.
Need to investigate further.
What kind of PIR was it?, if it was for an outside light, then they have light sensors built-in to stop them working during the day.

A burglar alarm type is probably best, as they don't have light sensors (for obvious reasons )

#### Semaphöre

##### New Member
How about a camera doing background subtraction? You could probably get away with a cheapo microcontroller for the processing since the resolution doesn't have to be very high. A bit more complicated to implement than a PIR sensor, but it's something to think about. I did this once and it worked quite well (I was using a webcam + raspberry PI).

#### Nigel Goodwin

##### Super Moderator
How about a camera doing background subtraction? You could probably get away with a cheapo microcontroller for the processing since the resolution doesn't have to be very high. A bit more complicated to implement than a PIR sensor, but it's something to think about. I did this once and it worked quite well (I was using a webcam + raspberry PI).
Rather over complicated, larger, and MUCH more expensive

Here's one of the first hits off google for PIR's:

As a matter of fact we've just ripped a load out at work and binned them - modern ones for commercial use require dual-operation, both IR and microwave.

#### dr pepper

##### Well-Known Member
My wife has a cheap ornamant that makes a noise (bird song) when you pass near it. It detects motion via a photocell, its probably capacitivelly coupled to a transistor amplifier.

#### tunedwolf

##### Well-Known Member
Well maybe I am confused about sensors.
I want to detect movement in a vehicle like a child left in a car seat or a pet.
Which is all fine and dandy providing they are actually moving around and not sleeping. Wouldn't it just be more sensible to look or, hmm, remember that you left your child in the back seat to begin with?

The better quality commercial vehicle alarms use microwave transmitters with doppler shift detectors internally as it is not interfered with by seating etc. I don't think there are many that still use Ultrasonics on the market and I have never seen any based on IR for movement detection.

#### MrDEB

##### Well-Known Member
That's a concern I am looking at. SLEEPING CHILD.
One thought was a sensor on the car seat but what if the child is big enough to not need a car seat or a pet left in the car.
If on the front seat then the seat belt sensor in the seat but back seats as far as I know do not have seat belt sensors.

#### alec_t

##### Well-Known Member
If you're concerned about exiting the car and forgetting the occupant, then all you need is a length of string with ends attached respectively to you and occupant

#### Nigel Goodwin

##### Super Moderator
That's a concern I am looking at. SLEEPING CHILD.
Perhaps you ought to mention EXACTLY what you're trying to do, a motion sensor obviously wouldn't detect a sleeping child as they aren't in motion.

#### Semaphöre

##### New Member
Rather over complicated, larger, and MUCH more expensive
I probably would have said the same thing, but if you poke around the web you can find some pretty impressive stuff these days for low cost:

-OV7670 camera modules, only $8. -There are Cortex-M3 or M4 development boards out, which give you more than enough RAM to buffer a frame and plenty of CPU power for under$20.
-And best of all, there's example code on the net for interfacing the two together!

So it's not much bigger (if at all), fairly low power, unaffected by daylight, and not particularly expensive. If one was really clever, you might even be able do face detection so you don't need to rely on motion at all.

It is definitely more complicated than just connecting a thing, but I think it's still doable?