I never have!
I wanted to measure the optical flicker of some new decorative lights that are advertised as being "constant lit".
Naturally, I thought I would just use a reverse biased photodiode and current sense resistor on top of a 9V battery. Then combined with my handheld portable scopemeter I could measure the brightness of these LEDs versus time.
I sacrificed a new 9V battery snap for the endeavor. Perhaps one could salvage the snaps of an expired 9V battery.
So far things look okay. Time will tell if I end up breaking the 9V snaps off... lol
My First 9V Topper Circuit
If I make a second topper circuit I could make a much more luxurious version of this circuit which includes a dual op-amp in a DIP package.
Testing in the Garden
Finally I get to the point of why I built the circuit in the first place! I was curious to see if these product claims were even remotely true:
They claim to be shimmer-free:
At first glance there dosen't appear any addition circuitry in the string lights aside from the LEDs themselves. The plugs look ordinary
(This isn't a blog post or content for competition so excuse the blurry photos for now :) )
Are the LEDs constant-lit?
No, but interestingly they LEDs are active on both halves of a line cycle:
I am still think about this one, it isn't obvious there is a bridge rectifier nestled away in the strand or plug. Perhaps each "LED" has two LEDs in opposing polarities?
Old skool LED Christmas lights are only active one half of the 60 Hz line cycle
Interesting...
