Here is the bulb, reflector and controller layout of the Darley signals that used one bulb to shine in all 4 directions. The original signal would have used a 150 watt bulb. I used 116 watt signal bulbs to save power, plus 150 was pretty bright indoors, so I had to use a socket extension to align the filament with the center of the reflector openings.
It's a magnetic induction wheel that turns a small camshaft via a couple of reduction gears. The cams would make or break contacts that powered the lights. Back when intersections had just one signal and before traffic actuation, this was a simple, inexpensive and practical way to regulate traffic. Some of these controllers ran for 40 years or more.
Yeah I am also impressed that ONE lightbulb in the middle of FOUR reflectors did the job too! I mean because the lightbulb isn't really INSIDE the reflectors, it makes it hard to see how well it would work.
By the way just to show how keen eyes I have, it isn't a socket extension...but a Edison to 2 prong adaptor plugged in by a 2 prong adaptor to Edison socket!
OK, you caught me. The actual socket extensions were about 1/4" too short so I replaced them. The reflectors actually did work pretty well. They kept phantom light from entering from the opposite side of the signal during early morning and late afternoon and the orange peel lenses tended to splash light back to the reflector that splashed light back to the lens. Pretty primative but with a 150 watt bulb they worked OK. I remember these as a kid. On the street they weren't as bright as the individual bulb models but you could certainly see them.
the reflectors more or less kept sunlight from shining in through one lens and out the other. Earliest Darleys didnt use reflectors at all. Latest ones used the current 12 bulb design
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By the way just to show how keen eyes I have, it isn't a socket extension...but a Edison to 2 prong adaptor plugged in by a 2 prong adaptor to Edison socket!