Flintlock76I've got to get one of those things to mount of the front of the car. Then the next time I'm driving at night, and some oncoming idiot refuses to dim his high-beams, will I have a surprise for him!
Problem is that the autoignition time for his paint and so forth is too long, a bit like using near-visible EM to make missiles fail.
What you want instead is something like the system Tom Clancy proposed to take down Japanese tanker aircraft. A very large capacitor bank discharging into a very large flash tube, mounted in a good front-surface reflector. Bet they get religion about high beams after that!
I'm a bit surprised something along these lines wasn't used 'back in the day' for streamliner recognition, where a rotating vertical searchlight beam didn't cause enough attention but periodic artificial lightning might have...
Didn't this turn into a fun discussion?
Continuing with the fun, how's about an arc light "Death Ray?"
Wait for it...
https://www.youtube.com/watch?v=u8e_u_xqN30
I've got to get one of those things to mount of the front of the car. Then the next time I'm driving at night, and some oncoming idiot refuses to dim his high-beams, will I have a surprise for him!
Flintlock76Well, I found this interesting video. Now certainly it's not a trolley headlight, it's a carbon arc searchlight, but the starting process is interesting. It starts at a dim setting, then the operator reaches inside, throws a switch, and BOOM! The light goes to the max!
What it appears you have is 'brilliant' and 'incredibly brilliant' more than what's normally intended for 'dim'setting. There is minimum brightness imposed by the physics of the arc and its interaction with the carbon, still brilliant blue-white; I can't tell whether there is a 'starting' current to establish the arc and then a switch to full amperage, or whether there is a setting of the carbon feed that adjusts the length.
A second consideration is that "dimmed" setting on many road vehicles also involves 'dip' -- the original meaning of low vs. high beams. Some early locomotive headlights had the focus of the parabolic reflector aimed at a fairly close point on the track, as evidenced by early images; it is possible that this was adjustable by shifting the mirror relative to the fixed light source. It stands to reason -- some reason at least -- that a carbon-arc light could have its light lowered, and some sort of filter or gel interposed in the light path to reduce the glare.
But I doubt you'd dim the arc effectively by tinkering with current supply, and there would be unpleasant effects by trying to modulate the electricity supplied from the DC overhead wire.
Flintlock76Were they dimmable, ot not?
The short answer is "no". While it is possible to set an arc lamp to delver varying levels of light, the light level is set by the length of the arc. Ironically, a short arc, that produces less light, may actually consume more current.
On most electric railways where arc lights were used, they were used outside the city limits. An incandescent headlight, either built into the dash or hung on the headlight hanger beside the arc light, was used inside city limits.
Bringing this one back to life, we had a discussion going about arc lights. Were they dimmable, ot not?
Well, I found this interesting video. Now certainly it's not a trolley headlight, it's a carbon arc searchlight, but the starting process is interesting. It starts at a dim setting, then the operator reaches inside, throws a switch, and BOOM! The light goes to the max!
So it looks like that searchlight had a dimmable option. Here's the vid...
https://www.youtube.com/watch?v=HWLmKcZtb-4
Been waiting three days to post this! Glad the Forum's alive again!
The lightweights were some of the last streetcars built that had 600 volts in the controllers (one each end) with K-type controllers (I think K-35), and a line-switch (crcuit-breaker) above on the ceiling. Even earlier cars, like the Brill 1931 Red Arrow cars, had low-voltage control systems controlling contactors for both resistancce insertion and removal and transition from series to parallel. In the traditional K-Type controller, this is all done manually by the controller handle and contact wipers and copper strips within the controller.
The lighting in the Broadway-42nd Street cars, 551-625, looked exactly like PCC lighting. These were the only Third Avenue cars with dropped celings, the others exposed the wood ceilings and had bare-bulb lighting just like the convertables and "box cars" (bowling-alley seating) they replaced. But the PCC-type glass diffusers were below the usual 32-volt bulbs arranged in a string for 600-volt operation. The streetcar 32-volt bulbs had a unique feature. When they failed, they shorted instead of opened. Thus, lighting would continue even before the single bulb was replaced. If more than one failed, then the added current and lower resistance would blow a fuse or circuit-breaker for the string.
The Third-Avenue foot brake is a complex story in inself, with push to the floor for release, and removing foot pressure to apply. Take your left foot off the pedal and emergency brakes apply and the front door opens. Creeping up to another car in the carbarn, you have your controller on the first point of power, maximum resistance in the motor circuit with all motors in series, and then depress and partially release the brakes with your left foot, inching up to the car ahead, as the automatic air-operated underfloor line-switch cuts in and out, out when any brake pressure is present. Fun cars to operate, and learned at age 15 in The Bronx.
Third Avenue Rail System's homebuilt lightweights had a belt-driven 24v generator running off the compressor shaft to charge batteries, used mostly for door controls as lights were still in 600v strings.
rcdrye PCC cars (even air-electric) have M-G sets and batteries. Many "standard" cars built in the 1920s and '30s have a battery charging circuit using the air compressor's voltage drop.
PCC cars (even air-electric) have M-G sets and batteries. Many "standard" cars built in the 1920s and '30s have a battery charging circuit using the air compressor's voltage drop.
An earlier example of using "voltage drop" to charge batteries was the 5,000V Grass Lake experiment, where the battery was in series with the traction motors.
M-G sets plus batteries have several advantages over series strings running off of 600VDC: Lights in parallel so one light burning doesn't darken the whole string; safety as 32V is much less of a hazard than 600V; Lights running at constant brightness; 32V lights more rugged than 120V lights.
Erik_MagAs for M-G sets, a very common arrangement was to connect a set of batteries across the low voltage generator (with a reverse current cut-out) this providing lighting in case of a dewirement or traction power outage. The C&LE high sppeds were so equipped as well as most PCC cars.
Correct me if wrong, but I think most of the 'Golden Glow' secret sauce was in the reflector design, which I dimly recall may have involved "back-silvered" uranium glass. I thought most of those lights were using Mazda-type tungsten bulbs soon after those were commercialized (which coincided roughly with 1915...).
I wouldn't be surprised to see the 'golden' reflector used with an arc source, but wouldn't expect a non-carbon (I.e. non 'flame' arc) setup to produce other than a blue-white native light. On the other hand if copper is the 'sacrificial' electrode we have another strong possibility for where Quimby's "green color" in the dimmed arc might come from.
Overmod Erik_Mag One way to "dim" an arc lamp is to reverse the polarity feeding the lamp, works best when the two rods are of different material. Don't think this is a good idea with carbon arc, particularly if some of the pre-magnetite systems of regulation and automatic feeding are being used -- all that reversing the polarity will do is cause the 'other' carbon to burn preferentially, and many of the feed mechanisms aren't set up for that. Does it matter in a modern short-arc envelope bulb which way the DC is applied? I did not think it did, but never thought about ways it might be designed to be 'dimmed' simply by reversing polarity. If one rod is more refractory, then it should certainly be possible to diminish the luminosity of the arc as struck, and it would be interesting to see how this might be set up in practice for interurban 'city' use.
Erik_Mag One way to "dim" an arc lamp is to reverse the polarity feeding the lamp, works best when the two rods are of different material.
Don't think this is a good idea with carbon arc, particularly if some of the pre-magnetite systems of regulation and automatic feeding are being used -- all that reversing the polarity will do is cause the 'other' carbon to burn preferentially, and many of the feed mechanisms aren't set up for that.
Does it matter in a modern short-arc envelope bulb which way the DC is applied? I did not think it did, but never thought about ways it might be designed to be 'dimmed' simply by reversing polarity.
If one rod is more refractory, then it should certainly be possible to diminish the luminosity of the arc as struck, and it would be interesting to see how this might be set up in practice for interurban 'city' use.
I will have to dig ito the literature on the "Golden Glow" headlights to get the full story, but my recollection was that it used one copper electrode and one carbon electrode. IIRC, the copper electrode was negative in normal operation (i.e. emitting electrons) and the carbon electron was emtting light (electrons striking a crater in the carbon electrode was heating the crater to incandescense). In reverse polarity operation, the copper electrode would be emitting light, and would be running at a lower temperature and thus producing a "golden glow".
N.B. I did find the source for reversing current to dim the arc - Electric Railway Engineering by Francis H. Doane published in 1915. The upper electrode was copper, lower electrode was magnetite in an iron tube. "High beam" operation was the copper electrode positive and lower electrode negative, low beam was done by reversing polarity and adding resistance.
As for M-G sets, a very common arrangement was to connect a set of batteries across the low voltage generator (with a reverse current cut-out) this providing lighting in case of a dewirement or traction power outage. The C&LE high sppeds were so equipped as well as most PCC cars.
rcdryeTo run a 150 watt 120 volt bulb on 600 volts the dropping resistance required is 384 ohms, the equivalent of four more 150 watt bulbs. To dim the bulb, just add more resistance.
But note: (1) how much power you use in order to use the bulb in the first place, and (2) to dim it, you need to throw away even more power in the dropping resistors.
If you wondered where the money for the motor-generator setup would come from, any long-term analysis of this situation (once electricity costs ceased being "internal" to operations of utility companies and the like) I think this explains much.
OvermodMaking incandescent fixtures that run on 600VDC is a somewhat expensive art; there are few if any bulbs made to operate directly at that voltage, and dropping resistors for that voltage are fairly expensive and wasteful
In most city cars the headlight was part of a string of bulbs. Depending on the reflector, a standard 56 watt streetcar bulb could be reasonably effective. Some systems used a higher-wattage bulb for the headlight in a string with lower-wattage bubs and dimmed it by cutting an additional bulbs into the string.
The dropping resistors used in the streetcars I have worked on are either cast segments similar to those used for motor control (but smaller), or nichrome wire on ceramic cores similar to electric heating units. Both would have been familiar to shop forces.
To run a 150 watt 120 volt bulb on 600 volts the dropping resistance required is 384 ohms, the equivalent of four more 150 watt bulbs. To dim the bulb, just add more resistance.
Erik_MagOne way to "dim" an arc lamp is to reverse the polarity feeding the lamp, works best when the two rods are of different material.
Starting in the 1920's, there was a trend to using an M-G set to convert 600VDC to a lower voltage with a further advantage that the lower voltage could be regulated (i.e. doesn't vary with trolley potential).
But you would not be using 'stick' arc lights with this in the first place -- assuming that voltage control, and not current control, would affect the effective arc brightness at comparable maintenance, and that there were 'enough' low-voltage services on the car to warrant the expense of a motor-generator setup in the first place.
Of course, there are other 'issues' with a motor-generator setup. When I was inspecting the Liberty Liner in the Rockhill Trolley Museum, they pointed out the small incandescent bulb in the MG box that always had to be kept burning or else! Condensation moisture would accumulate in there ... on the commutator and brushes ... and you could find yourself in Flashover City, very very unhappy, without much advance warning.
One way to "dim" an arc lamp is to reverse the polarity feeding the lamp, works best when the two rods are of different material.
E.J. didn't go into specifics as to how the "dim" option worked, however the Crouse-Hinds catalog is pretty detailed from what I've seen. Maybe they do?
I'd be very interested to see the arrangements made to dim the arc -- my guess being that the DIM position extinguished the arc and lit the incandescent.
I was wrong about the temperature, which is more characteristic of some short-arc fixed-envelope bulbs, and I should have known better because the carbon arc light (especially the flame arc type) and the steam-locomotive firebox share something very important in common: the luminance of vaporized carbon is often an important part of the light emission from a carbon arc lamp. The temperature is something like 6500 degrees F, considerably less than plasma temperature, and there is incomplete 'combustion' of the vaporized carbon (leading to acknowledged generation of carbon monoxide and the need to vent it carefully)
I have been advised that the 'green' arc indicates the presence of mercury in the light, an improvement made in the early 1900s and, I believe, improving the emission characteristics of a lamp using magnetite 'carbons' (an innovation permitting vast increase in the runtime of an arc lamp -- from about 110 hours up to 600 or more).
Here's how Commander Quinby described the arc light headlights mounted on the NJRT's Jewett interurban cars, I'll quote directly.
Two Crouse-Hinds Type L carbon arc headlights, demountable, supplied with each car, suspended from central bracket on exterior dash, each end, and provided with incandescant lamp on rim of hinged door, and two-conductor flexible cord and plug to match recepticle mounted under right side of bumper. Headlight transfer switch mounted inside dash in vestibule to left of controller, providing BRIGHT-OFF-DIM positions, connected to headlight through resistor, (for arc).
E.J. also mentions part of the motorman's duties was trimming the carbons of the arc lights and polishing the aluminum parabolic reflectors.
I should mention the arc lights were original equipment on the Jewett cars as produced in 1910. If they were ever replaced E.J. doesn't mention it.
For those interested, I found a link to a Crouse-Hinds catalog from 1922 It's 260 pages, probably more than anyone would want to know about their product line at the time, but here it is.
https://catalog.hathitrust.org/Record/100790552
Scroll down and click on "Full view." It's actually quite interesting.
Click on "Crouse-Hinds Company" for even more catalogs.
Flintlock76That's a kerosene headlight, or it sure looks like one. Rather odd, considering the trolley's electric powered.
Perhaps a 'remaindered' (or old-stock) steam-railroad headlight acquired cheaply. Note that the fuel tank is pressed/soldered integrally into the square base of the light; I think if you look carefully you can see the top 'seam' on the side panel. The curved top maintains draft more or less stable as wind, rain, etc. blow around the light and its surroundings.
Making incandescent fixtures that run on 600VDC is a somewhat expensive art; there are few if any bulbs made to operate directly at that voltage, and dropping resistors for that voltage are fairly expensive and wasteful.
Arc lights can be difficult to set up and run and involve interesting technology to regulate when the car is running (and the voltage is sagging, the car is banging in various planes, etc.) The arc gap is not 'fixed' (the carbon is continually burning away as the arc is 35,000+ degrees F) and a number of automatic devices compensate for this by raising one of the 'pencils' to keep the gap (or more precisely, the electrical characteristics across the gap) reasonably constant. Problem is, I don't think there is any way (aside from photo-type filters or theatrical gels and the like) to DIM an arc headlight effectively in the way 'city' incandescents could be -- it was a blue-white plasma extravaganza when on, whenever on. This might not be a happy thing for use in-town, particularly for pedestrians or oncoming traffic needing to gauge distance and clearance with the glare in their eyes...
As an old military man I'm really impressed by that topographic map of the St. Alban's area.
I've never been there, but it looks like it's in the middle of some mighty rugged country, especially the land to the east.
Arcs went out in the teens. Between the finicky nature of arc lights, some fires caused by the heat they generated, and improved incandescents and reflectors (the famous "Golden Glow") arc lights fell out of favor.
The North Shore and CA&E cars, except the Electroliners, had removable headlights, but I do not remember if they were incandescent or arc.
Here's an old map of the St Albans area. Click near the bottom to enlarge. The road west out of St Albans has tick marks to indicate it has a trolley track in it. It infers where the trolley line crossed the CV yard.
https://ngmdb.usgs.gov/ht-bin/tv_browse.pl?id=efcb3b7225a5ce997aa3ee72376e5792
https://www.nps.gov/nr/feature/places/pdfs/AD_74000211_09_18_2014.pdf
Jones1945 Flintlock76 That's a kerosene headlight, or it sure looks like one. Rather odd, considering the trolley's electric powered. As far as I know most trolleys had incandescant lamp or carbon-arc headlights. daveklepper Carbon-arc headlights could be quite large. Thanks, guys! Did the color of the light emitted from a carbon-arc headlight really change as its electrical characteristics change with temperature and time? Or was there any way to control the change of color? I saw some videos of carbon-arc headlight on YouTube, some emit purplish-white light, some are green.
Flintlock76 That's a kerosene headlight, or it sure looks like one. Rather odd, considering the trolley's electric powered. As far as I know most trolleys had incandescant lamp or carbon-arc headlights.
That's a kerosene headlight, or it sure looks like one. Rather odd, considering the trolley's electric powered. As far as I know most trolleys had incandescant lamp or carbon-arc headlights.
daveklepper Carbon-arc headlights could be quite large.
Carbon-arc headlights could be quite large.
Thanks, guys! Did the color of the light emitted from a carbon-arc headlight really change as its electrical characteristics change with temperature and time? Or was there any way to control the change of color? I saw some videos of carbon-arc headlight on YouTube, some emit purplish-white light, some are green.
E.J. Quinby in his book on the North Jersey Rapid Transit's interurban line* described the carbon-arc headlights on the cars as throwing a "blue-white" beam. He also said it was quite beautiful when it lit up a snow-covered right-of-way.
* "Interurban Interlude."
Most interurbans in the early 20th century either had no permanent headlight, or had a "city" incandescent headlight and a plug for the arc light. Many cars had only the bracket and the plug, used to advantage after the better incandescent lights became available about 1910. Inside the car was a resistance bank to drop the voltage as required, sometimes with two taps, one for dim and one for bright selected by a two pole snap switch. The bracket the portable light hung on was also the ground, so crew learned early to pull the plug before removing the headlight.
Jones 3D Modeling Club https://www.youtube.com/Jones3DModelingClub
Miningman Is this better?
Is this better?
Definitely! Thanks for that.
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