On 12/19/18 9:28 AM, Bubba wrote:

[snip]

Correct.Â* My strings of cheapo imported LED Christmas lights appear to
the naked eye to be on 100%.

A simple one would have the LEDs flashing at the powerline frequency
with a duty cycle of somewhat less than 50% (somewhat less considering
the time that the AC voltage is less than the LEDs threshold). Some
strings contain a full-wave rectifier so the frequency will be doubled
and the duty cycle almost (almost because of the diode voltage drops)
doubled (a little less than 100%).

Most of those strings I have have 50, 60, or 70 LEDs in two series, one
on each polarity. Both will not light at the same time (since they
require different polarities). I have tried it with a diode in series
with the string. Only one half lights. Reverse the diode and only the
other half lights. A string with a full-wave rectifier will light both
series (almost) all the time. The extra diode will give half brightness
(I have taken advantage of this for some tape lights that were too bright).

However, when viewed through my cheapo webcam, they appear on for 5
seconds, fade to off 2 seconds, off for 5 seconds, fade to on 2 seconds,
lather/rinse/repeat.

This is affected by frequencies in the camera. They do have interesting
interactions.

--
6 days until the winter celebration (Tue Dec 25, 2018 12:00:00 AM for 1
day).

Mark Lloyd
http://notstupid.us/

"Do not thank God for what man does." [Lemuel K. Washburn, _Is The Bible
Worth Reading And Other Essays_, 1911]