Hello,

What distance do you want to detect?
A PIR sensor can measure movements.(change of temperature)
A capacitive sensor can measure distance.(change of frequency of an oscillator)

Here are a couple of pages from the EDUCYPEDIA on sensors:
http://www.educypedia.be/electronics/sensors.htm

Sensors: Capacitive sensors Inductive sensors Piezo Displacement sensors Infra red sensors Pressure sensors Temperature sensor types Encoders and resolvers Magnetoresistive sensors Reed switches Thermocouple General overview Miscellaneous Temperature: PT100-RTD Tilt Sensors Hall sensor Optical sensors Temperature sensors Ultrasonic sensors

Bertus

 

Whew boy this is getting intense.
How can I simplify this project?
I'm thinking I may have to settle for something simpler.
Maybe I just get a some motion activated night lights and smash 'em up and modify them for my purposes. My concern is a lot of these sensors are quite large. I need a pretty small guy. 1/4" or smaller. I want the sensor to be hidden.
What I need is for the works to light up and shut off on their own as cheaply and simply as possible. The fade in and fade out is just what I want not what I need and it seems that the fade adds lots of complexity to the project. Which I need to avoid.
New suggestions?

 

I found this.

http://www.mpja.com/prodinfo.asp?number=17923+MI

It could work. I just wonder if the light stays on as long as it detects motion or does it cut out after 10 seconds then come back on.

Or is this something I could easily build?

 

Hello,

The main problem with the shown sensor is that there may be nothing in front of the circled part:

Bertus

 

What do you mean? I am thinking about taking it apart and separating all the LEDs maybe even replacing them. And take the sensor out too and conceal it where I want. So pretty much ditch the case and tear it all apart. I found it on amazon for 7 bucks. I don't think I could build something like that for less.

 

Hello,

The circled part is the motion sensor.
It reacts on very small heat changes.
If you put it behind anything the sensor will not work anymore.

Bertus

 

I know this. But judging by the picture that sensor is about 1/2 inch big which I think I could hide somewhere. Wouldn't any sensor I get need to be uncovered to work? The only type of sensor I can imagine working behind the face plate is the antenna like Theremin switch. Which sounds like it would work for what I want but looks very confusing.

 

Hello,

A theremin switch is what I meant with the capacitive sensor.
A plate behind the sculpture will work.
There are a lot of schematics for those sensors around.
Here is a link to a simple example:

http://www.theremin.us/101/101.html

This is a link from the theremin page:
http://www.thereminworld.com/schematics.asp

Bertus

 

the 2 Items I linked to in my first post on this thread, are available as pre made modules, you just have to wire them up and connect them together to get them to work, the sensor is approx 1/2"x 3/8", can be easily hidden in one of those opaque spots in the sculpture itself, as long as the infrared can shine through it, it will sense a presence....

In the LED control circuit portion, you will have to remove the potentiometer, and replace it with a 2N3904 transistor and a couple of resistors, you should be good to go, if the proper resistors are chosen for the pulldown on the base of the transistor, when the sensor does not sense anyone, the lights could be completely off, and as the person gets closer, the higher the analog output from the sensor, hence causing the LEDs to turn on and brighten up.... and most likely a 4 AA battery pack will still be huge compared to both of those items, so the biggest issue you will have is the battery placement ....

B. Morse

 

wouldn't a A theremin switch require the person to be pretty close to the "antenna" before anything happens?? the IR sensor I linked to can detect a presence up to 5 feet, which ought to get people's attention from a distance.....

Or possibly a "microwave" presence detector they use in automobile alarms, these are normally installed in convertibles to sense when someone intrudes on a certain radius of the opening...

B. Morse

 

Hello,

The sensitivity of a theremin is mainly depended on the size of the detection plate.

A radar detector could penetrate the sculpture (depending on type and frequency) and detect people in front of it.

Bertus

 

Yeah everything I read about the theremin switch says it has to be very close. The infrared switch you linked to looks great but that plus the PCB for the dimmer control puts me at the high end of my budget. Also don't I need to get all the parts for the PWM Dimmer Controller. Or does the kit come with everything you need. It kinda looked like you just get the empty board.
Is it possible for me to just get the infrared switch, wire that to some batteries and LEDs and add the dimmer control down the line if I want to?

 

How long does this have to operate between battery changes?

Is it going to be part of a show that is open for 6 hours a day or so, then you could change the batteries if you had to?

 

They will be eventually part of a show but right now I just need to finish them. Optimally the batteries would last days. That is one reason for the sensor so they only light up when someone is looking at it.

But is my plan feasible? To buy the Sharp Infrared Proximity Sensor and wire that to some batteries and a few LEDs. Will I need anything else? Is that sensor as easy to use as like any switch?

I need to place some orders and get this project started.

 

They will be eventually part of a show but right now I just need to finish them. Optimally the batteries would last days. That is one reason for the sensor so they only light up when someone is looking at it.

But is my plan feasible? To buy the Sharp Infrared Proximity Sensor and wire that to some batteries and a few LEDs. Will I need anything else? Is that sensor as easy to use as like any switch?

I need to place some orders and get this project started.

Here is a quote from the datasheet:

1. Touch-less switch
(Sanitary equipment, Control of illumination, etc. )
2. Sensor for energy saving
(ATM, Copier, Vending machine, Laptop computer,
LCD monitor)
3. Amusement equipment
(Robot, Arcade game machine)

This device outputs the voltage corresponding to the
detection distance. So this sensor can also be used as
a proximity sensor.

So, yes, it can be used as a switch, as long as it is used properly... But one thing to keep in mind, that this sensor is "directional", meaning it will only sense an object in it line of sight, if you are wanting it to detect a presence in a wider range or area, maybe a theramin setup may suit your needs more...

as for the circuit I linked to in my post, I had made a different version of it based on some components you can readily get at Radio Shack if you had to, here is a copy of that circuit I revised..... If you are handy with a soldering iron, maybe you can get some perf board from radio shack too, and just do a point to point soldered circuit by hand





B. Morse

 

A micro controller with an ultrasonic distance detector could activate and change the brightness of an led according to distance.

I think this option would be the easiest and cheapest. You could buy some ready made setups of go to your local auto wreckers (oopppsss sorry...recyclers) and get some reversing sensors out of a few old bumpers. You may also be able to get the rest of the circuitry as well. Ford and GM have already done all the hard work for you. You just need to adapt it. You could even have a second set of sensors for when they get too close to trigger an MP3 player to tell them to back off. Should get a giggle or 2.

 

Oh! What a great idea, parking sensors.
I have been finding electromagnetic parking sensors that have LED displays. More LEDs light up as the object gets closer. How perfect.
It does mention this...The detection range is greater for big conductor, narrower for small nonconductor
So the bigger wire loop the better I guess.
It says it start sensing things around .7 meters which is not bad. If I could get that just over a meter it would be perfect.
Now I gotta find the best price and some 12 volt batteries.

 

Electromagnetic parking sensors, usually are designed to sense a vehicle, not a person.

As for the backup sensors used in vehicles, those are ultrasonic sensors, which could work, but require more circuitry and possibly a microcontroller.

B. Morse

 

Actually there are a number of very inexpensive parking sensors as well as "driveway alert monitors" you'll see from time to time on Goldmine or at Harbor Freight Tools.

 

I think I found the winner.
eBay comes through with a Car Parking Sensor Infrared LED display Distance Kit.
I can just wire more LEDs to it and as people get closer different sets light up. Sounds all good but will infrared detection detect people?

Thank you so much for everyone's suggestions and help.