IR Switch Trigger in Specific Setup

[wfarid]

Hello everyone! I'm an artist and I want to make a lightbox that turns on only when you get near it. I have a shelf which is part of the installation where I will to place all the electronics. I want the lightbox to turn on when you are around 40 cm away from the shelf or closer. As soon as you step away from that distance the lightbox turns off. Thus it can only be activated when someone is near it. I want the system to be really robust and incredibly simple, which is why I am shying away from ardruino. There may potentially be hundreds of people who throughout the piece's time being displayed could trigger it, so reliability, consistency, and ease of repair/part replacement is really important.

Thanks for all your help and happy holidays!

As you can see, my sketchup friend is totally not interested in the artwork, but hopefully you all can help!

 

[hevans1944]

A passive infra-red (PIR) motion sensor driving a timer to set the "ON" time after it is triggered should work. You might even be able to buy one off the shelf. The tricky part is setting the sensitivity and the field of view so passers by who don't stop to view the art won't trigger the light box on. Perhaps add a capacitive proximity sensor to the shelf that enables the light box after the PIR turns it on and then turns the light box off when the person triggering it walks away. Or ditch the PIR sensor and just use the capacitive proximity sensor.

PIR sensors only respond to motion, so you do need either a fixed time on after triggering, or some way to detect when someone walks away from the display. Don't you just hate it when a public toilet with a PIR sensor flushes prematurely?

I am sure others here will chime in with other ideas. If you see something you like, maybe we (the forum) can develop a circuit or solution. Good description of the problem by the way.

 

[dorke]

What ever happened to the art button?
As simple as it gets,or not...

 

[wfarid]

A little background - maybe it'll make things clearer -- I shot these images behind the counter of stores. So I'd like to recreate that environment in a gallery. Just like there is an exchange at the counter, I want there to be an exchange between the viewer and the image - hence it only turns on when someone is in front it.

I'd like to avoid any timers, and just have it be really responsive.

Thanks for all the input!

 

[AnalogKid]

ebay has plenty of low-cost PIR and ultrasonic people detectors that will work reliably in the 15" range you cite. What power source is available for the control electronics, and what are the voltage and total wattage of the lights?

ak

 

[wfarid]

That's the power supply.

The specs are 110-240V 50/60hz ; 1.5 Amp

Output 12.0V - 5.0 A


Should I put the sensor controller in the connection from the lightbox to power supply or power supply outlet?

Any assistance will be greatly appreciated!

 

[wfarid]

The lights are 12V LED's. I'm not sure how much wattage they are consuming but I wildly guessing something in the range of 10 - 50 watts.

 

[cjdelphi]

The problem with pir/infra red is that

1. It will trigger when it senses motion not really distance there is an adjust but even low it might be too sensitive as it has a wide view field (so neighbors might trigger it)

2. Regardless of how close you are it will turn off until you move again

The ultrasonic sensor will give you a range of distance and you can make sure it stays on until the person steps away backwards or side to side

But it requires a mc/arduino

 

[wfarid]

I'm ok with working with MC/Arduino - can arduino control a power supply like the one shown above?

 

[cjdelphi]

10 - 50w is a lot, i mean a LOT, 10w is about as much light as you need before you start blinding people..

If you can find out how much current draw will be, you can pick a mosfet best suited for the job, a 50amp mosfet might be over kill if all you need is 1amp at 12v (10w)

So yeah, arduino can no problem, you just need a bit of extra circuitry

 

[wfarid]

I just got the exact amount in wattage for the leds - its 24 watts total (they are sidelight, not backlight). Any guidance on how to design the circuitry for this? Also where should it be positioned? Between DC inverter --> leds or between the power source --> dc inverter

 

[AnalogKid]

The inverter already has power switching parts; better to let them do the work than to add more power switching parts between the inverter and the LEDs. If possible, it would be good to use the output from the body sensor to turn the inverter on and off with its shutdown control pin - if it has one. Also, what powers the body sensor when the inverter is off?

ak

 

[wfarid]

I'm assuming a standard socket (we have 240v here) could supply the power body sensor. I'm guessing there would have to be something to provide the body sensors the proper power.

Not sure where the shutdown control pin would be - I'm guessing I'd have to open it up to find it.

 

[AnalogKid]

Sorry, I drifted into building the inverter from scratch. Are you looking to build a circuit, or connect together pre-made modules? IOW what is your electronics skill set?

ak

 

[wfarid]

My electronics skill set is pretty basic. I've hacked my xbox, replaced op amps in my sound card. I can solder things together if I have a good set of instructions. The best case for me would be putting together something that is mostly built and needs minimal programming etc.

 

[BobK]

As you can see, my sketchup friend is totally not interested in the artwork, but hopefully you all can help!

Hey, your sketchup guy looks a lot like me (when my hair is not dyed as in my Gomez picture). I've been digitized!

Bob

 

[AnalogKid]

Relay module that will work as the interface between the sensors and the LED power source.
http://www.ebay.com/itm/24V-1-Chann...872003?hash=item2c8e3c3743:g:Y0IAAMXQ74JTT-M4

ak

 

[wfarid]

Wouldn't this work because of 12V

http://www.ebay.com/itm/1-Channel-1...257040?hash=item33a5a30790:g:JwgAAOSw~gRVn0Qf

 

[wfarid]

How would the HC-SR04 connect to the ardruino 12Volt board?
Because the beam angle is very narrow is there a way I can array 2-3 of these together?

 

[wfarid]

I also noted that the spread of the beam is 30 degrees -- the shelf will be 900MM wide. Below is a rough spread (its more than 30 degrees but just a rough idea).