A very sensitive, very efficient Motion/Proximity sensor design

Thread Starter

iONic

Joined Nov 16, 2007
1,653
Did you think I was offering a great new design? Unfortunately I am not. But I am hoping that through some brain-storming from all of you we might be able to obtain it.

Suppose you have a circuit that senses nightfall and turns on a single LED. Now suppose that you have it located within view but are not interested in using it full potential(3-4 LED's). What we need is a very frugal way to detect that someone has come close enough to the light to realize that they are now interested in more light! Thus we need a way to detect this and crank up the light until that someone has left the scene.

Since the direction of approach is unknown I was leaning towards a sound activated switch of sorts that stays on as long as the sound intensity is loud enough. Maybe an sensitive mic fed into an ultra-low power logarithmic op-amp/comparator circuit could do the trick, I don't know. Bottom line is that if the operation of this sensing circuitry drawn more power than the extra 2-3 LED's then all is mute.

Any suggestions??
 
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scubasteve_911

Joined Dec 27, 2007
1,203
I'm really sorry, but I am seriously confused about this paragraph.

"Suppose you have circuit that senses nightfall and turns on a single LED. Now suppose that you have it located within view but are not interested in using it full potential(3-4 LED's). What we need is a very frugal way to detect that someone has come close enough to the light to realize that they are now interested in more light! Thus we need a way to detect this and crank up the light until that someone has left the scene."

'within view' - of what?
'very frugal way to detect that someone has come close enough to the light to realize that they are now interested in more light' - who wants more light?

I'd like to think I am of average intelligence and yet I cannot understand the problem. I would like to help if you cleared it up a bit for us.

Steve
 

Wendy

Joined Mar 24, 2008
22,362
Basically a motion / heat sensor so the lights only turn on when someone is around. I think this is a solved issue, you can buy off the shelf.
 

Thread Starter

iONic

Joined Nov 16, 2007
1,653
Basically a motion / heat sensor so the lights only turn on when someone is around. I think this is a solved issue, you can buy off the shelf.
You are saying that there are motion sensors or heat sensors that can detect in a 360 deg. fashion, someone within about 10 feet(3 meters) of the device?

Can you suggest a part!

Remember, it needs to operate with very minimal power so as not to drain the batteries more than if all the lights were on in the first place.
 
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Thread Starter

iONic

Joined Nov 16, 2007
1,653
I'm really sorry, but I am seriously confused about this paragraph.

"Suppose you have a circuit that senses nightfall and turns on a single LED. Now suppose that you have it located within view but are not interested in using it full potential(3-4 LED's). What we need is a very frugal way to detect that someone has come close enough to the light to realize that they are now interested in more light! Thus we need a way to detect this and crank up the light until that someone has left the scene."

'within view' - of what?
'very frugal way to detect that someone has come close enough to the light to realize that they are now interested in more light' - who wants more light?

I'd like to think I am of average intelligence and yet I cannot understand the problem. I would like to help if you cleared it up a bit for us.

Steve
"Suppose you have a circuit that senses nightfall and turns on a single LED. Now suppose that you have it located within view but are not interested in using it full potential(3-4 LED's). What we need is a very frugal way to detect that someone has come close enough to the light to realize that they are now interested in more light! Thus we need a way to detect this and crank up the light until that someone has left the scene."

'within view' - of what? - circuit
'very frugal way to detect that someone has come close enough to the light to realize that they are now interested in more light' - who wants more light? - someone or anyone, or a human being...
 
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beenthere

Joined Apr 20, 2004
15,819
Mats are available that act as electrical switches, providing a closure when stepped on. Using such a mat/s will give the proximity signal with no use of power.

Otherwise, you might consider and share by what means you wish to sense human proximity, and quantify "frugal". If "frugal" is under 400 watts, then no problem. If you mean less than 4 mw, that could be a challenge.

BTW, "frugal" generally applies to monetary cost in the sense of being unwilling to incur such.
 

Thread Starter

iONic

Joined Nov 16, 2007
1,653
Mats are available that act as electrical switches, providing a closure when stepped on. Using such a mat/s will give the proximity signal with no use of power.

Otherwise, you might consider and share by what means you wish to sense human proximity, and quantify "frugal". If "frugal" is under 400 watts, then no problem. If you mean less than 4 mw, that could be a challenge.

BTW, "frugal" generally applies to monetary cost in the sense of being unwilling to incur such.
A mat or mats would not be practical, or cost effective in this application.
Frugal, in the context in which I was referring meant efficient, expending less power than running three additional white LED(3.6V @ 20mA).
 

Wendy

Joined Mar 24, 2008
22,362
I like the RF sensor (thermin) idea. I have also seen motion sensors using IR that can see over 120 degrees, you would need 3 of them for full coverage, but these were comercial products. How much power they consume is anyones guess. I have also seen ultrasonic motion sensors that might fit the bill.

Problem with all of these is I don't see any of them, except maybe the RF sensor, fitting your power requirements.
 

Thread Starter

iONic

Joined Nov 16, 2007
1,653
I like the RF sensor (thermin) idea. I have also seen motion sensors using IR that can see over 120 degrees, you would need 3 of them for full coverage, but these were comercial products. How much power they consume is anyones guess. I have also seen ultrasonic motion sensors that might fit the bill.

Problem with all of these is I don't see any of them, except maybe the RF sensor, fitting your power requirements.
Bill,
I'm not sure exactly what a RF sensor (thermin) is. Perhaps an PIR sensor as Digi Dave suggested might work. I might have exaggerated a bit when I said 360 degrees, 90 or 120 degrees will suffice, i'm sure.

The main issue here would be it's max effective distance for triggering and the power requirements.


Just found a site that describes all sorts of sensors. This should give me an idea for options.

http://www.educypedia.be/electronics/circuitssensors.htm

.
 

Wendy

Joined Mar 24, 2008
22,362
A thermin is 2 RF oscillators tuned to the same freq. One is sealed and insensitive, the other open and very sensitive to outside influence. The two signals beat together, or are recieved on an AM radio. If the sensitive xmtr drifts a tone is heard. This tone could also be used to trigger circuitry.
 

blocco a spirale

Joined Jun 18, 2008
1,546
Ahh, what's the model number of those Sharp infra-red active proximity detectors favoured by small robot builders? I have some somewhere... gp202/212 ? You would need more than 1 to cover 360. Conserve power by only energising the detection circuit at intervals for the minimum time it takes to get a reading.
 

Thread Starter

iONic

Joined Nov 16, 2007
1,653
Ahh, what's the model number of those Sharp infra-red active proximity detectors favoured by small robot builders? I have some somewhere... gp202/212 ? You would need more than 1 to cover 360. Conserve power by only energising the detection circuit at intervals for the minimum time it takes to get a reading.
blocco,
In my case it would be GP2Y0A02YK(6in - 5ft) costing $11.00 at mouser.

http://document.sharpsma.com/files/gp2y0a02yk_e.pdf

But you right about needing more than one.

I may have to use just a switch to go from 1 LED to 3-4 LED's, or a pot to switch 1 to 2 to 3 to 4 LED using a LM3915?

Nice device though, if it's what you were referring to.
 

Thread Starter

iONic

Joined Nov 16, 2007
1,653
The IS417F Proximity Detector looks interesting, but I can not find anywhere in the datasheet where it specifies distance, although it mentions application uses such as printers, faxes... This seems to say that it is far from what I am looking for!
 
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