White LEDE strobe circuit link

See this link:

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for a circuit to strobe white LEDs. As I suspected, and had confirmed here and in the above link, the persistence of the phosphor is so long that 100 Hz is about the best you can do. This may be fast enough for me. That translates to 6000 RPM. For many of the things I want to measure that would be OK. But there are some things I want to look at that need higher strobing speeds. My CNC mill for example has a top spindle speed of 7500 RPM. While I can already measure the speed with a tach, which agrees with the speed reported by the control, I want to see the tool sitting still. Eric

Reply to
etpm
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There is a problem with that, you can't expect to view the still image of your tool in the quill if it's under load(cutting), the drive system I doubt will maintain a steady RPM enough to get a stable image.

What you need is to put a detector on the shaft somewhere and then a variable delay trigger leading the index, this way you can view all sides of the tool in motion. The only error you'll have is if the quill happens to change its state during the delay trigger, but I think that would be minimum compared to a synchronous operation.

Jamie

Reply to
Jamie

Greetings Jamie, I want to look at the tool when spinning but not under load. I'm curious about what the spindle is doing just by itself. I think it may be fluctuating more than it should at high RPM. Eric

Reply to
etpm

Ok, would be interesting if you can get enough luminance from the cluster of LED compared to a flash tube. A reflector would most likely help.

Jamie

Reply to
Jamie

So use blue or ultrabright red.

Reply to
Ian Field

Is green viable? So use red + green + blue. Adjust counts to get near white.

Reply to
BeeJ

Why can't a bright *red* (or any other basic color) LED be used? In fact, a red laser diode can be used if you need more brightness, and these things can be pulsed and still visible to a human all the way up to 100KHz and perhaps even faster. Naturally, you would have to wait a few (thousands of) cycles for the flashes to register in your eye if you're talking 10mks flashes.

Reply to
passerby

on 4/23/2013, passerby supposed :

http://www.electr>> etpm wrote:

How about R G & B Leds in triads? Are there not some that include all three together in one package? Steerable color types.

Reply to
BeeJ

Sure, if the OP really wants a *white* strobe. I was just curious what makes white color so special for a strobe that it cannot be a coherent bright flash of any color, really. Red may be a little difficult to pick up on a black background but it all depends on the brightness. Besides, one can put a nice reflective stripe on the spindle (I've a pen with silver acrylic paint - marks anything and is reflective like hell) and either lower the required brightness or increase the frequency of the flashes - whatever is required for the application.

I think using bright blue makes it a little easier than white to pickup the mark if the surface is small - blue makes little details stand out more. High speed license plate readers are usually lit with blue(ish) - looks like almost half the way to UV even. So, in reality perhaps OP might even benefit from using a color strobe rather than a white strobe.

Reply to
passerby

And tri-color would give any color the op wanted.

Reply to
BeeJ

--
Why not use a Xenon strobe lamp?
Reply to
John Fields

there is one tiny problem - the 3 LED chips can't physically occupy exactly the same place inside the encapsulation, at a distance this is not significant, but at close quarters there will be some divergence of the individual beams - there will be at least some colour fringing round the edges.

Reply to
Ian Field

Ian Field brought next idea :

I could live with that. Where can I buy a complete unit?

Reply to
BeeJ

I built a strobe like that. We were making these strobes to go on automobile wheel hubs (a stupid idea IMO, but what the customer wanted). The idea was to give the spokes some forward/reverse appearance whilst driving down the street (this is the Fast and Furious mind set)...

The white leds show quite a bit of "tailing" when observed on a scope via a photo diode, and didn't have the sharp definition of a xenon strobe (blurry spokes).

Xenon was out of the question for size and ruggedness, but a RGB led in a "Piranha" style package worked well (and added a whole new level of complexity since the customer now wanted fading colors or the ability to match the color scheme of the F&F decor).

I thought blue-white had the greatest impact.

Reply to
default

There is yet another tiny problem - the 3 LEDs require different Vf each, the red & green are fairly close but the blue is almost double. You can't just strap the 3 in parallel.

The first place I'd look is probably Farnell, but outlets may be different where you are.

Reply to
Ian Field

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