Strobing Using RGB LEDs Instead Of Flash Tubes

Hi,

It would be good to mention the actual use-case (e.g. photography? nightclub?). Otherwise, you may end up with a solution that doesn't meet your needs.

Its application is for something like a night club.

So more like flashing lights than a strobe...

I want it to flash as if it was a xenon tube. Just like a camera, but very quickly(about 60 times a second). I see many of these things on Amazon, but I want to flash just like a party strobe but with shifting colors.

I want it to flash as if it was a xenon tube. Just like a camera, but very quickly(about 60 times a second). I see many of these things on Amazon, but I want to flash just like a party strobe but with shifting colors.

A simple 555 timer can generate a square wave signal to trigger a MOSFET or transistor easily at 60 times a second, 16 milliseconds, which is the same frequency as the AC outlet.  

How you approach it depends a lot on how much like a Xenon tube you want it to be.

Xenon tubes produce very short very high power flashes.

(I had a quick hunt around the internet and you would expect less than 100us pulse length. If the average power is 10W at 60 flashes per second that about 1600W during the flash.)

If you want "freeze" human movement you may not need to go so fast  - I'm going to guesstimate that quick wavy hand or arms move at about 5m/s and to avoid blurring you want the flash to last the time the subject moves no more than 1cm - which results in a maximum flash time of 2ms and a power during the flash of about 160W.

You can overdrive an LED so long as the average power is within spec - but the light output won't go on increasing as the current rises.

let's look at some high power LEDs

Here's one from Farnell:

You can put 1.3A maximum into it, and the efficiency is falling off at that level, you could push it a bit further maybe with short pulses.

At 1.3A the forward voltage will be 4.3V so you'll be putting 5.6W in during the flash but the average power will only be 166mW with 1ms flashes.

To get a decent level of brightness you will need 10 of each colour and a peak current of 13A per colour. The average power will only be 6.4W.

As  shabaz suggested white LEDs will be easier and brighter (but I expect you want colour).

This may seem a bit over the top - but you did say you wanted very bright !

It's not that easy - or cheap -  the LEDs will cost at least £20 but I think the power drivers will cost the same again. Almost any Arduino could manage the 1ms control pulses.

MK

michaelkellett said:

As  shabaz suggested white LEDs will be easier and brighter (but I expect you want colour).

There's an English stage / art lighting specialist on EEVblog (Mike), who says that - if significant brightness is needed - he always uses white LEDs for white. Even if there is demand for colour, he will add the white ones in the mix.

I visited this place with some friends ages ago:

https://www.youtube.com/watch?v=kW4U5zdb8F0

It's like an alternate reality where pretty much the _only_ lighting that exists throughout is strobe! I was just amazed there were no fights, considering you couldn't see anyone else for the (quite lengthy) 95% of the dark time in-between the flashes!  Bumping into others was inevitable, no way to avoid that there!