In wife’s hometown in China they have a single-lamp traffic signal! [o] Has just RED and GREEN LEDs I believe.
Red illuminated with green creates YELLOW, so they get all three colors!
(This could be a problem for colorblind males. Such is why our signals have blue-green GREEN signal lamps.) Also we have lamp position when vertical traffic signals.
Red and Green make dark yellow - almost brown.
Yes, but when emitted light, it produces yellow.
So it’s easy to have just RED and GREEN LEDs in the lamp face.
Do they create yellow with alternating current to the R&G LEDs?
Or have Direct Current to the Red and Green LEDs?
I could not see them “strobing” on 50 Hz power.
House curent in China is 220 Volts, 50 Hz.
I am hoping to make all of our lights run on pure DC current.
We can still see the flickering of our AC powered LED bulbs.
LED-light bulb manufacturers should be ashamed.
LED = Light Emitting Diode, hence they only conduct in one direction (i.e. DC current). Multiple LEDs can be driven simultaneously or in a sequence (using their phosphor persistence) to create alternate colors but for certain applications, a more complex phosphor is added to the LED to generate wavelengths other than the “native” emission spectra.
Alternating current will illuminate the red LEDs in the “positive” half of their 50 Hz cycle and the green LEDs in the negative half of the AC sine wave. So just two conductors would accomplish red, green, and yellow!
Wish China allowed GooglEarth Street view so I could see if the [o] istill there.
Would you PLEASE spell you words correctly and not that VERY Childish combined BS c.r.a.p you keep doing???..
Double extra big plus, Dave.
Serious question - many people are tired of RG and his juvenile behavior. Most of his posts are just the same stuff about his speeding while delivering Blood to places. Yes his volunteer service is to be commended but true volunteers don’t need to pat theirselves on the back constantly.
So why is he allowed to continue this stuff that really is not Cartalk related ?
What, no ground reference? 
It takes the same number of conductors either way. And you still need a way to turn the half sine wave on/off unless you just want one solid color. Easier to just use a PWM and DC pulse to drive them…
I’m just trying to imagine what would happen if all three sets of LEDs (Red, Yellow, Green) deployed after a typical red cycle.
What would drivers do? 
There may be only Red and Green LEDs.
Flashed alternately at 50 Hz, they produce a Yellow perceived by the human eye.
The red LEDs would be connected opposite polarity to the green LEDs.
Connected to just two wires, + to - displays red, - to + illuminates green.
AC would cause both colors to alternately illuminate 100 times/second, creating a perceived yellow.
But I could be entirely wrong about how dey do dis.
Perhaps the signal lamp [o] has Red, Yellow and Green LEDs.
-
Reminds me of the mee-mool lights (o)T(o) at a manned Mexico City railroad crossing.
At the same flash rate as American grade crossing signals, the signals flashed alternately:
The switch which the crossing guard turned on was hanging by its wire down the outside wall of the guard shanty.
As soon as the locomotive occupied the crossing, he turned the signals off.
Of course, a green Volkwagen taxi accelerated across the track just feet in front of the locomotive!
Saw another picture of a massive Chinese traffic jam. 36 lanes merging into four. Just physics I guess. They probably shot the engineer. Reminded me of trying to get out of Boston before Columbus Day. Not much of a holiday in the Midwest, just no mail.
