Radio Controlled LEDS?

[blueroomelectronics]

Since it's for a special effect, be warned most video cameras will pick up the IR leds (they'll glow purple)

Why not just do the effect in post processing? When is the deadline?

 

[crazylegsmurphy]

That radio graphic is just that, a graphic. Think more like waves in a pond when you throw in a stone for a simple antenna.

The devices will have no idea when they're a foot away, signal strength will give them an idea but the signal strength will vary depending on objects nearby. Triangulation would work but is very complex.

Well this is kinda what I was thinking. I mean an RC car can still drive even if the person controlling it is spinning in circles, on top of a roof or whatever. My understanding is that radio waves just travel in 3D space in all directions until they hit something (as waves in a pond)....if it can hit the other device as you bring it close...it seems like it would work.

I think I get what you're saying, but since there will be nothing in the way of the three devices when brought together, it should just get the full signal, no?

Omni directional RF or IR plus LED displays will likely chew through tiny batteries very quickly. Low power design takes some skill and there are always tradeoffs.

Your LED flashlight wasn't turned ON for two years...

This is the second problem. This project becomes pretty useless if the lights only work for like 3 minutes. I don't expect it to stay on for days or months, but the effect has to last a reasonable amount of time. In reality they won't be together 24/7, they might only be together for a short amount of time (maybe 20 minutes), but the batteries have to last long enough so the user can bring them together for short periods of time and have it work...like a flashlight.

 

[arhi]

Since it's for a special effect, be warned most video cameras will pick up the IR leds (they'll glow purple)

Why not just do the effect in post processing? When is the deadline?

darn, I totally forgot about this, if those "gadgets" are to see the ir, the cameras will see it too ... there goes the idea

nice catch blueroomelectronics

 

[blueroomelectronics]

Why not just hide a switch or tilt switch on the device, let the actors figure out when to turn it on. It's just a prop afterall.

 

[crazylegsmurphy]

Since it's for a special effect, be warned most video cameras will pick up the IR leds (they'll glow purple)

Why not just do the effect in post processing? When is the deadline?

These won't be filmed, they're practical props for stage so it can't be done in post. There is no deadline.

Why not just hide a switch or tilt switch on the device, let the actors figure out when to turn it on. It's just a prop afterall.

There are many typical ways that I would make this prop...hiding a cord along the actors arm and adjusting it with an offstage switch is the easiest, but while there are a lot of practical solutions to this, I'm trying to keep it all self contained, with no external switches. Half the awesomeness of this project is actually getting that to work...it's where the interest lies for me.

 

[blueroomelectronics]

There is ALWAYS a deadline, else it must not be needed. You did say "movie" prop.
Is the resin going to be clear so you can see the insides? Are the batteries going to be replaceable or molded in? How large do you want it to be?
Seriously put a switch in it. Teach the actors how to use it, it's an illusion the audience won't care.

 

[Torben]

I'm trying to make a movie prop. I'm a special make-up FX artist and I am trying to create something that will work the way I described above.

I just need three devices that when brought together will "see" each other and allow the Microcontroller to do fancy things with the LED's. I want to find the simplest, smallest, most cost effective way to do this.

I hate to say it but I think you could save yourself a lot of time and development headaches by skipping the automatic part of this and just building the devices so you can control them remotely. When the scene is cued you'd have someone bring up the fader or whatever so the lights brighten.

I am however guessing that you've already discarded this idea as unsuitable.

I'm getting frustrated because I see devices all the time in my life that do similar things to what I want, but it apparently doesn't translate into this project.

If there was a more simple way to do this, I would totally do it...but I'm running out of ideas.

I wonder whether RFID could be made to work. I think each device would need both a passive RFID tag and an active RFID reader, and I have no idea how small those are. Some have a max range of a foot or two. Unfortunately I've never used them so someone with more experience will have to tell you whether the idea is even worth looking into.


Torben

[Edit: RFID would still have directionality, but that's physics for you.]

 

[crazylegsmurphy]

arhi..

Really? It got through all those? hmmm...

I mean I have IR stuff all over the place in my home. I can change my TV from random places, my IR remote for my camera will usually work if I am not directly in the line of sight....and such..

I just want to be sure I won't have an issue with the resin before I go ahead with it. Basically I want to get your guys' expert opinions before I go out and buy anymore stuff. I just spent $180 on the RF materials only to find out it probably won't work....so I need to be sure the solution I choose to test is the best one.

Just so you have and idea everyone:

**broken link removed**

This is what the inner resin will look like...it will also include an outer shell of semi-opaque resin so you can't the inside....so it "looks" solid.

There is ALWAYS a deadline, else it must not be needed. You did say "movie" prop.
Is the resin going to be clear so you can see the insides? Are the batteries going to be replaceable or molded in? How large do you want it to be?
Seriously put a switch in it. Teach the actors how to use it, it's an illusion the audience won't care.

No, the deadline is my own. The batteries will be replaceable via a cap in the bottom that allows the core to come out so I can replace and service the electronics. Each device will be roughly 18 cm in diameter, and about 10 inches high.

I agree with you, the switch idea is the simplest way, but it's not what I am looking to do. I don't mean any offense or anything, but I know there are practical ways to do this and I have done many props that do such things, but for this one, I really am trying to do something different....for my own pleasure, and a learning experience.

I wonder whether RFID could be made to work. I think each device would need both a passive RFID tag and an active RFID reader, and I have no idea how small those are.

I thought of that....I have FOB (a thing for getting into my underground parking) and it basically does the thing I'm trying to do. It's super tiny and when I put it close to the pad by the entrance it "sees" it and lights a little LED, then opens the parking door. I can do that thing through my window on cold days...and it has about a foot range. I don't know anything about them though, nor could I find anything online to get me pointed in the right direction.

 

[blueroomelectronics]

For those I'd go with RF and a guy sitting offstage with a transmitter.
Edit:
Keep it Simple, RF may or may not be reliable and live stage would be a drag if it didn't work.
Why not a simple timer and a magnetic switch hidden inside to start the clock.

 

[crazylegsmurphy]

blueroomelectronics:

You think like a true FX artist!

I think we're getting caught up on the details of them being a "movie" prop. Lets assume for now that these won't be used on stage, on film, or anywhere where it matters it goes perfect.

Think of it as a personal project that needs a solution that fits what I'm trying to do, and not the reason they're made. This is more for me to make them work, so I can have them for my own personal satisfaction.

The reason I am doing this now (and not for an actual production) is because I want to gain the knowledge in case I ever HAD to do it. I want the "tool" at my disposal so if I have to apply it to something for whatever reason, I can do it. Trying to research something like this on a deadline would drive me insane!

 

[blueroomelectronics]

Problem is there is no easy solution.
RF receivers will probably have some form of AGC which means they will constantly adjust their gain depending on what's going on around them.
You'll probably want them bright enough to see so you'll need some very powerful LEDs inside if you want them to be seen by the audience (Flashlight LEDs are very directional, not what you want) so it'll chew through batteries. Look at 1W Luxeons they'll plow through 350ma so you'd need a powerful battery and when they're diffused they may or may not be bright enough to be seen by the entire audience.

 

[crazylegsmurphy]

(Flashlight LEDs are very directional, not what you want)

I thought about that, and that's why I opted for 5 LED's. One pointing up, the othe 4 pointing outwards. My hopes are that the resin will disperse the light enough so it'll look alright, and not like a bunch of tiny LED's.

I dunno, I knew this wasn't going to be easy, but it simply can't be impossible. I realize there will be limitations and such, but there has to be some somewhat simple solution that'll give me a reasonable effect for a reasonable amount of time.

It seems like all of the solutions suggested would just almost work depending on a few factors. I keep skipping back and fourth between solutions based on what people are saying, but there has to be one that everyone can agree is the best possible solution despite the downfalls, and figure out a way to make it work.

 

[blueroomelectronics]

Then start by illuminating one crystal, see how it looks on the stage. Standard LEDs are not very bright when diffused, the Luxeons are better for sure but get nice and hot.

 

[crazylegsmurphy]

Well..

The only other solution is to use standard mini lightbulbs...but the downfall of that is that a few of them will probably drain a battery 5 times as fast as LED's.

I'm open to different types of bulbs (Wedge Base Bulb, Halogen, etc) If any of you have another idea for bulbs, then please suggest them. LED's were my first choice due to power consumption and heat. These things can get a little hot...(not burning hot), but some reasonable heat is fine. The bigger concern is the power consumption.

 

[blueroomelectronics]

You'll have to build some prototypes and see what looks the best.

 

[crazylegsmurphy]

arhi,

I keep going back to what you were saying before about your experiments with IR.

- glass of water - working
- glass filled with ice - working
- glass filled with glass marbles - working
- thick green plastic bottle (Cl acid was in there before) filled with glass marbles - working
- thick black plastic bottle (from sulphuric acid)- NOT working
- pack of CD's - NOT working

It seems that "glass filled with marbles" is pretty similar to the resin I would be using. I think as long as I can get a signal strong enough to reach a foot in all directions (using 5 IR LED's for example in a circle), then it just might work.

I mean, if it can go through a bottle with marbles, this might stand a chance of working. I'm trying to think of something in your home that you might be able to use as a test for me.

Now...here is the million dollar question....

What are we looking at in terms of power? Let me do up a little diagram...brb.

**broken link removed**

So IF that worked...and the IR LED's could see through the resin (this is yet to be determined), then would this idea do the following:

- Run in "sleep" mode (devices not together) for a reasonable amount of time.
- Be able to be run (when devices are together) for a reasonable amount of time.
- be able to adjust frequencies and have the microcontroller/IR's pick up the two signals and recognize them?

 

[crazylegsmurphy]

And sorry...one more question...what actually picks up the IR signal?

 

[blueroomelectronics]

A TSOP34838 is a good choice if you want it to ignore stray IR sources.

 

[crazylegsmurphy]

Receiver?

So you need an IR transmitting LED and then that TSOP34838 to see it. Now do you just get different frequency LED's for them (38kHz - 30kHz - 40kHz) so they all have a unique signature, or do you get one say 40kHz and adjust the output?

 

[blueroomelectronics]

The 38KHz will see +/- about 5KHz so all units will see it more or less. You might try a 58KHz TSOP, some will still leak through.