[time-nuts] Reducing lab noise with LED lighting.

Chris Albertson albertson.chris at gmail.com
Mon Sep 17 16:59:08 UTC 2012


On Mon, Sep 17, 2012 at 9:23 AM, Bob Camp <lists at rtty.us> wrote:
> Hi
>
> The other advantage of the pre-made bars is that they fit into conventional
> fixtures. Glare from a wide open high intensity LED can be pretty nasty.
> Diffusers and reflectors can be good things. Glare is what has very much
> slowed down my deployment of LED's at home...

The rule I was taught is that the "hardness" or "softness" of the
light is caused by the apparent angular size of the light source from
the user's position.  In other words a lamp that is many degrees wide
casts softer shadows.  With leds they are so tiny you have to use them
indirectly.  If they are reflected off a surface or defused through a
panel the effective size of the light source is the spot on the panel
or reflector that is illuminated by the LED.    The LEDs are so tiny
that it is easy to get a 100X improvement with even a small defuser

You standard 100W Edison base light bulb comes with a built-in
defuser, the glass envelope is much larger then the filament.  You
need something like that at the very least, or simply aim them at a
while ceiling.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Chris Albertson
> Sent: Monday, September 17, 2012 11:53 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Reducing lab noise with LED lighting.
>
> On Mon, Sep 17, 2012 at 8:08 AM, Tom Knox <actast at hotmail.com> wrote:
>>
>
>> The conversion will cost about $100 on the surplus market if you had none
> of the needed items and should pay for it self over the next few years in
> energy costs.
>
> If you care about energy costs AND getting the maximum brightness you
> really need a constant current power supply.  You can't use a current
> limiting resister as that will just turn your power into heat.  The
> old PC power supplies are voltage regulated.  Linear voltage
> regulators and series resisters are both easy to use but if you care
> about power costs the only way to go is a constant current SMSP.   You
> can make a dimmer by adjusting the current output.
>
> Or you can simply buy pre-made LED light bars that are the exact shape
> to replace fluorescent bulbs.  They fit into existing fixtures.   At
> work that replaced all the bulbs in the parking garage and not only
> did each stick use less power but they were able to leave almost half
> the fixtures empty.   Payback should be in a few years.
>
>
>
> Chris Albertson
> Redondo Beach, California
>
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-- 

Chris Albertson
Redondo Beach, California




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