# DIY Surgical overhead / hanging light



## rice81

I would like to build an overhead surgical light vs retrofit an existing incandescent one. These are the types that are used in the OR and are usually two or three in number. The older lights were incandescent or HID, hot and heavy. Sure enough, LED's have taken over and now they the way to go. 

Here is an example:

http://i01.i.aliimg.com/photo/v2/418706647/LED_operation_lamp_surgical_light_with_CE.jpg

Much of the expense is the boom and the engineering that goes into the hanging lamp as the old ones were very heavy and required special ceiling mounting. I am going to take an older existing lamp, use the power available in the device (24VAC, 150 W) to power the retrofit. The details of design will depend on the led units I choose. I plan to cut a round plate that approximates the size of the face of the original fixture and mount spot led units on the plate with the appropriate angle to converge at an operating site a few feet away. No doubt it won't be as precise as an existing LED surgical light, but won't cost $8000 either. These new surgical lights use either a clear plastic lens or a reflector like a flashlight or a reflector like a car headlight (LED backwards for more focus) to achieve a focus.

The specs on LED surgical lights is typically 50,000 to 100,000 lux per lamp. These lamps generally cover about one square foot or less of operating area. This area is roughly a tenth of a square meter, which means that there must be around 5,000 to 10,000 lumens of light from the combined LEDs on the lamp.

So with this information:

need 10,000 lumens from multiple 'focused' led units over a round area of about 3 square feet, focused at a 1 ft square area a few feet away.

I need to choose these LED units. This first thing that I came across was the 12V MR16 LED halogen replacement unit. These units are small, cheap and focused via reflector and there are something like 15,000 of them on ebay and are touted as having 350 to 550 lumens at 4 to 9 watts or so depending on what Chinese seller you choose. The size, wattage, voltage requirement and light output are compatible with the project so I am leaning toward ordering a dozen or so and building a trial model. So I really have a few questions:

1) What do you think about MR16 LED unit vs another standard LED unit (Cheap LED bike lights, another LED fixture, some kind of flashlight head, etc) in an array for this purpose?

2) If I choose the 12V LED MR16, any thoughts on a good source? There are a million of them out there from $2 to $6 with about the same specs. There are 3x1 watt, 3x3 watt, 5x3 watt, etc. Many are sold in lots of 10.

3) Any other general comments about this project?

Thanks for reading . . .


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## rice81

Further searching into MR16 threads reveals lots of bogus claims from Chinese sellers at too-good-to-be-true prices. Would be a big disappointment to build a big array of MR16's only to have failures due to improper heatsinking or 'fake' LEDs. There are indeed some cheap ones. Maybe I'll order some and do some measurements or look for other LED assemblies. Would like to keep the cost down, though.


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## jspeybro

perhaps posting a picture of what you will reuse might help to see what we can fit in there.
do you have an idea of what angle of light you want.

using metric units may make things easier. I don't know if a 1 feet square area is something like 1 foot by 1 foot or if that exists in a 2 dimensional size as well and feet² is 30-ish cm²?... sorry.

do you want some light outside the illuminated area or preferably only in that rectangular/round area?


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## jonwkng

Hi *rice 81*,

Looks like you've taken on quite a big task there. Most centers follow the IEC 60601-2-41 standards when it comes to surgical lighting. You might want to start there.


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## WeLight

Do you need cynosis observation type?


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## DollarIn

You won't be able to find a MR16 bulb with the required output.

My advice would be to modify the existing light housing to use a COB LED, something like the CXA series from Cree would be ideal in terms of light output and quality.


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## Polymerize

jonwkng said:


> Hi *rice 81*,
> 
> Looks like you've taken on quite a big task there. Most centers follow the IEC 60601-2-41 standards when it comes to surgical lighting. You might want to start there.




rice81, I notice you mentioned IEC 60601. I am working on finding a manufacturing facility that can manufacture to IEC 60601 standards. A few of the collateral standards apply, but not too many. Do you know any flashlight manufacturers that are able to manufacture to IEC 60601 standards?

Thank you in advance for your assistance.


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## Oogabooga

Two weeks ago i helped retrofit 4 of these into a hospital. The new units were >$25 000 each.


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