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Re: Why two red lights (o)-(o) which flash alternately?
Posted: Sun Nov 01, 2009 8:12 am
by Robert_Gift
luke wrote:Robert_Gift wrote:
...I prefer the instant on, which is so unnatural that it attracts one's gaze...
I don't really like that because at night, they could disorient a driver, IMO.
Nice photograph, Rrxingrick!
Love the uniform deep rich
red lights.
They
should dim the lights at night.
But I do not understand how they would disorient anyone.
Maybe blind someone by contrast. (That is why the middle higher
red brake light on a vehicle is made not as bright as the two lower tail brake lights.)
(I slept and missed my cell phone changing to 0200 at 0300.
I told all my acquaintences to be sure to remember to set their clocks
forward one hour.)
Re: Why two red lights (o)-(o) which flash alternately?
Posted: Sun Nov 01, 2009 1:43 pm
by Crossingman18
Smjh1979 wrote:cabman701 wrote:But in most cases they are
MUCH too bright at night. Just my
worth.
You mean like this?
How the hell does one get a shot like that?! I want to try that!
Re: Why two red lights (o)-(o) which flash alternately?
Posted: Sun Nov 01, 2009 1:47 pm
by Smjh1979
Time lapse delay. Some cameras have this function. None of mine do.
Re: Why two red lights (o)-(o) which flash alternately?
Posted: Sun Nov 01, 2009 1:49 pm
by Robert_Gift
Crossingman18 wrote:Smjh1979 wrote:cabman701 wrote:But in most cases they are
MUCH too bright at night. Just my
worth.
You mean like this?
How the hell does one get a shot like that?! I want to try that!
12-second timelapse, if the lights blink at 1 flash per second.
Re: Why two red lights (o)-(o) which flash alternately?
Posted: Sun Nov 01, 2009 2:56 pm
by gedunk
Robert_Gift wrote:Crossingman18 wrote:Smjh1979 wrote:cabman701 wrote:But in most cases they are
MUCH too bright at night. Just my
worth.
You mean like this?
How the hell does one get a shot like that?! I want to try that!
12-second timelapse, if the lights blink at 1 flash per second.
Which is why they appear so bright in that picture. Multiple flashes on the same section of the camera sensor (or same spot of film)
will lead to areas of over-exposure. Try doing a long exposure of a dim incandescent crossing, and it will "brighten up" quite a bit.
Re: Why two red lights (o)-(o) which flash alternately?
Posted: Sun Nov 01, 2009 11:50 pm
by CIC755
fgossage wrote:As far as I've always heard, it was designed to simulate the old wigwag indication for "stop", but without any moving parts.
I'm curious though why a triangular three light setup wasn't used instead, something like the following to more closely resemble the old wigwag:
(o)-------(o)
----(o)----
Probably one of those cases where the answer has been lost to time.
(Edited to get diagram to look better; now it reminds me of a British grade crossing signal).
Re: Why two red lights (o)-(o) which flash alternately?
Posted: Mon Nov 02, 2009 12:01 am
by Robert_Gift
CIC755 wrote:fgossage wrote:As far as I've always heard, it was designed to simulate the old wigwag indication for "stop", but without any moving parts.
I'm curious though why a triangular three light setup wasn't used instead, something like the following to more closely resemble the old wigwag:
(o)--|--(o)
.......(o)
Probably one of those cases where the answer has been lost to time.
My thoughts exactly!
Probably because the extra relays needed would add expense and complexity which is more prone to failure.
The two lights use just two relays, each of which builds magnetism until it draws its armature and closes its contacts, which thenergizes the other relay.
Clever thathey did not require special timing circuits to regulate the light flip-flop relays!