Electronic shutter?

Reset time desired?

Mechanical acceptable?

LCD is the way to go generally.

How close is the strobe allowed to the helicopter?

A refelctive paint or film could be affixed to top of one of the blades. An LED in scope would emit light toward reflective film, receiving the reflected light back into amplified photostransitor circuit. With proper mechanical arrangement, there will be a noisy mark/space signal. A digital discriminator using Schmitt trigger would feed result into latched counter that drives buffered readout periodically, say once a second.

-Le Chaud Lapin-

Yes, I have seem them. At the LCD factory, they have all the messy hardware behind the "electronic window" and be hidden at the flip of a switch. They also installed them in the bathroom of the hotel next to them. All the glass walls turn opaque when the door is closed. It was pretty cool.

The LCD glass is not expensive, but shipping without breaking is expensive.

I don't understand what that is. I just want it flipping between transparent and opaque at an adjustable frequency.

No. The point of my project is to improve on the mechanical ones. Primarily due to battery drain, but also weight, response time and reliability.

Yes, that's what I was thinking too. The problem is, I can't seem to find a device like that.

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RoRo

There will not be a strobe at all. The sunlight illuminates the rotor. The shutter device will be held in front of an eye, and if the frequency is right, the rotor will appear stationary.

The device must be able to work at at least 10 meters, preferably more. With the technique I described, range is not a problem.

Nope. Nothing can be attached to one of the blades. If anything, you'd have to attach the same to both blades, but it is still not ideal. I'd like to be able to tach any helicopter without any preparation. I might even want to sneak a peek at a competitor's machine to see what head speed he is flying.

That method is not practical in this application. The helicopter will be moving around, even if the pilot tries to hold it steady.

--
RoRo

Yes, that the kind of thing I was thinking about. Now, where do I get those in really, really small sizes, for a reasonable price?

Since I'd need less than a square inch, shipping should not be a problem.

--
RoRo

You need ... 3D eyeglasses!

They're built for gamers and are set up to sync with the video image so that the left and right eyes get alternate frames. The early ones (I tried an nvidia set) were, IIRC, only good for low frame rates but I'm sure the technology has improved.

Figure out the connector pinout & interface and you're there. An advantage is that they look like geeky sunglasses so you could do stealth intel gathering on the competitors' helos.

I haven't used mine in ages (probably couldn't find them inside of a week's search) and all the links I have are ancient.

However, here's a possible starting point:

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Rich Webb     Norfolk, VA

You can get cheap LCD shutters from gaming glasses. For your application, the glasses are probably just what you need. Some have electronics which you can rip out and replace with your own. You may be pushing them at 100 Hz shutter rate.

--
Mark

That's a great idea. They're surprisingly inexpensive, too.

If I could get 60Hz out of them, they'd still be quite useful. I suspect they may only do 30Hz, though, since the essentially only need to "see" every second frame on the monitor.

I'll get a pair and see if I can figure out how they work.

Thanks, Rich and Mark.

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RoRo

S-tek used to make a 1" square shutter for product development, I'd give the newer faster stero glasses a try , as well.

remember to ac couple the lcd, dc bias eats the LC material

Or, use the ghost image from a AO cell.

compared to what you need AO will have a infinate ( ~ 7 Mhz) bandwidth, but you may need to add two spherical lenses to magnify the image and seperate the diffracted light from the zeroth order.

cheap AO:

Before somebody tells me that AOs are not good for imaging, only laser beams, think again. And yes I've done it.

Steve Roberts

"Robert Roland"

** Tiny DC motors exist the draw only minute amounts of current and quick response to speed control inputs is only matter of using PWM drive with air-load braking to the motor via the slotted disk.

IOW - the shortcomings you see are only the result of poor ( likely amateur) design.

.... Phil

I see.

What would happen if you could achieve the same effect of the slit by momentarily blinding the observer with (annoying) low-intensity LED projecting its pulses onto a semi-transparent mirror through which observer observes helicopter?

[Incidentally, a few months ago, I developed an unhealthy obssession with aircraft, in particular slow-moving aicraft, like helicopters. Much fun but, IMHO, there is a very large amount of abuse of Bernouilli's principle in aerodynamics.]

-Le Chaud Lapin-

Try 'Shutterglasses' for computer 3d

should be able to get something for

Nothing, because you couldn't.

Look up "afterimage".

Sorry, Rich

Except you need something even faster for the stated purpose. Alternatives include rotating prisms and mirrors also speaker type drives. All of which can be garage shopped.