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

[Mark Sims]

I have considerable experience with LED lighting.  My house has over 300 light bulbs in it!  They are now all LED bulbs.  You can read about some of it here:  http://budgetlightforum.com/node/9179

A few observations and recommendations:

Avoid all Chinese led bulbs.  They spew more hash than a cheap diner.  Also I have never seen one that meets it's output specs.  Only use bulbs from well known,  name brand makers.  I like Sylvania/Osram,  Philips,  and Lighting Science Group bulbs.

Avoid those Chinese LED array chips.   Their light quality tends to the bad side of awful and again I've never seen one meet their advertised specs.  Look into arrays made by Bridgelux.  They have proper datasheets and specs.

Do not drive an led with rectified AC...  120 Hz flicker can be quite noticeable with an LED.

You CAN direct drive an LED with a regulated voltage.   You have to match the voltage to the LED and be aware of the Vf shift as the LED heats up.  A ballast resistor helps even things out.  An LED driven through a ballast resistor can be more efficient than a switching regulator/current source if you choose your voltage source to be close to the LED Vf.