_ LED Lights: Criss - Cross light beam contamination/cancellation ?

[iMisspell]

The lighting in my basement sucks, ceiling is only 6'8" so the light will not spread and seeing at the mill is tough (right now im using a magnetic LED, want something better).
Been wanting to get a "donut ring" of lights around the quill and seeing a post in the Tools thread got me motivated.
Just bought a set of LED Car Strip lights, 4 strips - 11" long (each).

The plan is to make a flange for the bottom of the mills head and create two rows of lights about 7" in diameter, the inner row will point straight down, the outer row will be set at an angle focusing the light beams more to the center of a cutter.

Since the outer rows beams will be "shooting through" the inner beam, will it "cancel" each other out some how ?

I could always angle the inner row, but the question popped into my head and thought i would see what people have to say.

_

[darryl]

You won't see any effects at all.

[macona]

No, you would have to have coherent light and I dont think you are using laser for lighting!

[danlb]

The light is additive. Two LEDs will be twice as bright as one, same as two incandescent are twice as bright.


Dan

[jhe.1973]

Hi Eveyone,

I think it was last spring that there was a thread talking about using LED ring lights from fast food auto parts stores. That got me thinking - which is always dangerous!

I bought 8 twin pack LED flashlights on sale at Harbor Freight with the intention of using as many as I could fit (6 - 8) on a ring around the quill of the mill. I will mount them on short arms so that they can be focused with different length and diameter tools & to be able to get past my boring bar.

I find that single point boring is when I have my head closest & trying to see what is going on at the point of the tool.

I figure on using a 12 volt wall wart & had a friend who helped me build an EDM figure out what I needed in the way of a resistor for each light unit.

He found that they draw 600 milliamps @ 4.5 volts so I would need one 47 ohm, 3 watt resistor per light.

I got as far as getting the resistors & cutting the first one. Life has gotten in the way since. Here is what I have so far:



Someday I might even finish this one!

[velocette]

Hi
As always looking to improve things in the workshop and lighting is of interest to us all.

LED ring Lights are very popular Google "Angel Eyes" and I am sure that you can come up with lots of Info.

Eric

[JM95]

I bought a Wal-Mart Halogen(35 Watt) desk lamp with flex arm down to a weighted base that I removed. This is a Mainstay Black Lamp, UPC-0082803005406. They are only available from Wal-Mart.COM. Their cost $9.97 plus shipping. The flex shaft has a threaded base that makes it easy to attach to a piece of aluminum angle and bolted to any part of the Mill or drill press. I now have 2 on each . I added a miniature Off/On switch from Radio Shack mounted in their small plastic box with removable side plate for control.

I have had cataract surgery and still have trouble getting enough light on my work area. I now have 6 of these handy desk lamps on various pieces of equipment. The bulb is 120 volt, 35 watts and available everywhere. No power supply as with LED's. I do use a 750 Lumen, Led bulb, 120 volt, directly over the Head of my engine lathe. Pricey but great light source for my 75 year old eyes.

[jlevie]

I like to have a 4' double tube flourescent above the mill and a bit forward of the head. That gives even illumination to the working area.

[TGTool]

The OP's question isn't too far out. Light beams have actual substance as demonstrated by this account.

Two guys are making their way through the cemetery at night after leaving the pub. Stumbling through they both tumble into an open grave excavation. Not seriously hurt they set about to climb out but can't get any purchase on the vertical dirt walls. Finally one of them has an idea and pulls out a flashlight.

Shining it up towards the rim at the opposite side he says to his buddy, "Just edge your way up the beam to the top and then you can get some help to get me out."

"Oh, no!" his friend says. "You won't catch me on that trick. I'd get about three quarters of he way up and then you'd turn out the light."

[ironmonger]

Hi Eveyone,
<<snip>>
I figure on using a 12 volt wall wart & had a friend who helped me build an EDM figure out what I needed in the way of a resistor for each light unit.

He found that they draw 600 milliamps @ 4.5 volts so I would need one 47 ohm, 3 watt resistor per light.


Someday I might even finish this one!

I have a small LED flashlight with a Cree lamp. It runs either off an 3.7V Ultracharge lithium rechargeable or a pair of CR123A 3V lithium primary cells. The latter totals 6 volts.

The current limiting on these flashlights is built into the lamp housing. The multifunction bits are there also. That's how they function from 3.7 volts to 6 volts with out any noticeable difference in light output. It is possible to purchase a lamp housing that just turns on and off or has high-med-low- strobe functions, if you are building all the fancy stuff into this housing it only makes sense to include voltage regulation as well.

While the current draw most certainly did equal what ever you measured, it's a pretty sure bet that the power draw wouldn't have changed much with more voltage.

This is, of course, mere speculation on my part regarding your flashlights. The only way to find out is power it up with higher voltage and see what happens. I think I may have one of the older multi lamp units floating around... If I can find it I will try it and let you know...

paul

[darryl]

Jim, I have the guts of one of those sitting on my desk. It looks to me like all the leds are wired in parallel, and I don't see a resistor. I think they are banking on the fact that a triple A will lose voltage right away when loaded that much, so the three AAAs in series becomes a voltage limited current source. Terrible way to drive the leds. If it's indeed drawing 600 ma, that's almost 70 ma per led- they will burn out and they do. I'd limit the current to something like 35 ma at the most, which means about 300 ma. You'll have a chance at them working for a decent length of time. A better way to drive them would be to supply 3.2 volts regulated to them. That would keep the current through any one of them within limits, even when they start to burn out. Otherwise as they burn out, the remaining ones will get higher and higher current and they will burn out in quick succession.

[RandyZ]

Even if you did set up "standing waves", they would too short for you to see anyways.

[jhe.1973]

Jim, I have the guts of one of those sitting on my desk. It looks to me like all the leds are wired in parallel, and I don't see a resistor. I think they are banking on the fact that a triple A will lose voltage right away when loaded that much, so the three AAAs in series becomes a voltage limited current source. Terrible way to drive the leds. If it's indeed drawing 600 ma, that's almost 70 ma per led- they will burn out and they do. I'd limit the current to something like 35 ma at the most, which means about 300 ma. You'll have a chance at them working for a decent length of time. A better way to drive them would be to supply 3.2 volts regulated to them. That would keep the current through any one of them within limits, even when they start to burn out. Otherwise as they burn out, the remaining ones will get higher and higher current and they will burn out in quick succession.

darryl: Thanks for the additional perspective.

IIRC I gave my friend the 12 volt source idea 'cuz I already had one. Since then I have found plenty of lower voltage ones at thrift stores etc. and may use those instead. I even found a universal wart w/several voltages available just by selecting them w/a switch.

Would I be safe to figure that doubling the size of the resistor to 94 - 100 ohms would drop the voltage enough to limit the current to what you suggest?

I have a good understanding of electricity, but lack the solid state & digital application of it so thanks again for the help.

[ironmonger]

Jim, I have the guts of one of those sitting on my desk. It looks to me like all the leds are wired in parallel, and I don't see a resistor. I think they are banking on the fact that a triple A will lose voltage right away when loaded that much, so the three AAAs in series becomes a voltage limited current source. Terrible way to drive the leds. If it's indeed drawing 600 ma, that's almost 70 ma per led- they will burn out and they do. I'd limit the current to something like 35 ma at the most, which means about 300 ma. You'll have a chance at them working for a decent length of time. A better way to drive them would be to supply 3.2 volts regulated to them. That would keep the current through any one of them within limits, even when they start to burn out. Otherwise as they burn out, the remaining ones will get higher and higher current and they will burn out in quick succession.

Wow... good call Darryl. I never looked inside the one that I have. That's flakey.
I went back to find the listing that had the loose lamp moduals.
All the other ones that I have are Cree's or cree knock offs, and have dirvers built in.
These are the single power level ones.

see:

http://www.amazon.com/350lm-Ultrafire-Cree-1-mode-Surefire/dp/B00A4E9DMI/ref=sr_1_84?s=hi&ie=UTF8&qid=1389655022&sr=1-84

although this is the same price:
http://www.amazon.com/gp/product/B005E48K6I/ref=cm_cr_ryp_prd_ttl_sol_1

paul

[ironmonger]

darryl: Thanks for the additional perspective.

IIRC I gave my friend the 12 volt source idea 'cuz I already had one. Since then I have found plenty of lower voltage ones at thrift stores etc. and may use those instead. I even found a universal wart w/several voltages available just by selecting them w/a switch.

Would I be safe to figure that doubling the size of the resistor to 94 - 100 ohms would drop the voltage enough to limit the current to what you suggest?

I have a good understanding of electricity, but lack the solid state & digital application of it so thanks again for the help.

Darryl was figuring about 30 mils per LED. That's 240 mils for the cluster of 8. That needs a series resistor of 50 ohms to set the current to 240 mils. That resistor at 12 volts needs to be at least 3 watts. If you increase the resistor to 100 ohms the current drops to 15 mil per lamp... if that works your home free. That also reduces the wattage rating to 1.44 calculated or a 2 watt resistor.

If you find a 5 volt wall wart that can supply 500 mils or so, you would then need a 20 ohm resistor with a 1.2 watt rating or so.. 2 watt would be great. For each lamp of course.

Kind of looking like the halogen lamps would be simpler.

paul