Photographic Ring Flash/light

Hi all,
Please could you have a look at this video. I want to reproduce this ring light.


This guys explanation seems fairly straight forward, however I can't see any use of resistors for these white LEDs which should be at least 3v or 4v. Also I cannot see if these LEDs are parallel or serial. Also he seems to be running 64 LEDs off of 2 or 3 AA batteries. The LEDs can't be getting much power, can they?

Could you please tell me the best way to create this circuit with DC power preferably.

Thanks
Paul

probaly in parralel just look for the right leds and make the rest

Can anyone else offer any advice.
Thanks
Paul

Thunder pretty much said it all. It's just a whole bunch of LED's in parallel.

Just google LED ringlight, there are plenty of other projects out there.

I just want to say, that this is absolutely useless for anything but macro work though. The LED's don't give off near enough light to be useful for anything more than a foot away.

EDIT: Doing a simple google search on 'DIY LED ringlight' this was the third link down, and it even has the schematic in eagle and in an image.
Fuzzcraft.com | Ring light 2.0: 90 LED ring light | Photography, audio and light DIY projects

You could always use 1 watt LED's but that's not so simple to hook up =)

paulbacca said:

these white LEDs which should be at least 3v or 4v.

Click to expand...

Yes, white led's typically have an inherent forward drop of between 3.2V and 3.8V, and 4V is well within the spec at operating current - so this really shouldn't work at all.

In practice, however, I've found some white LED's will operate down to 2.8V, so it's just possible to run them off a pair of fresh AA batteries. Not for very long, though.

paulbacca said:

The LEDs can't be getting much power, can they?

Click to expand...

That style is rated for about 60mW each, so 64 of them would draw nearly 4 watts, total, at about 1.28A.

Since the voltage is very close to the battery voltage and the loading is high, this is one of a few applications where you can run the LED's without a resistor.

Battery life would be lousy, though. The led's aren't going to run at 2.5V, and there is still considerable power left in the AA batteries when they have a loaded voltage of 1.25V each.

I'd use a 3 battery pack and a decent resistor or possibly easier and better a transistor as a current limiter/source