OK, this is an old post--hope you guys see this! In 2010, I made a fully operational replica of a GE Magnetic Auxiliary ballast for 1 F20 lamp. The ballast is a rare Japanese 4-coil series choke from a 1970's Panasonic desk lamp I sacrificed for this ballast, the same 4-coil design was used in the GE Mag Aux ballast because with the large core and 4 coils in series-parallel with each other, the ballast losses were kept to a minimum to maximize system efficiency--these 4 coil simple choke ballasts could have as little as 1/2 to 1 watt loss versus 2-5 watts loss for simpler, smaller common single coil chokes. The 4 coil units have the same wiring set up--2 wires as any basic choke ballast. Then I took a relay from a RTU air conditioner (Roof Top Unit) we junked--a commin type of relay with double pole double throw contacts rated 30 amps, and a 24 volt AC coil. I gutted out an old, dead, but still rare Sola "Sequenstart" 2 x F96T12 ballast, with the top lid on it instead of a cover on the back like regular common ballasts use. This gives me an open-top ballast can that the cover can be lifted off of to show the "works" and since the GE "engineers" at The Edison stupidly lost the cover on me, a plexiglass cover will be made--as I said before GE engineers are "dumb as a box of rocks" these days. Anyway, I wired the NORMALLY CLOSED contacts, just one set out of the 2 in the relay, to the starter loop of the lamp like a regular starter is. Now, the ballast choke and relay are nestled in this old ballast can, and the wires (cloth, of course!) run out through the original wire openings in that case. There are only 4 wires. 2 go to the normally closed contacts of the relay as mentioned above, and 2 go to the "line" input of the ballast, and the "lamp" side of the ballast then goes to one terminal of the 24 volt coil in the relay, then the remaining coil terminal of the relay gles out to the lamp, as if it were the regular lamp wire of a simple choke ballast. This puts the coil of the starting relay in series between the ballast and lamp, so all current going to the lamp must also go through the relay coil. Thus the ballast choke and starting relay, which coins the name "Magnetic Auxiliary" because the STARTER is a magnetic coil relay, coil are in series and go to the lamp. as I said the normally closed contacts are wired across the lamp ends, and the last pin on the lamp goes back to the opposite side of the line, just like a regular preheat unit. This is how the GE units were done as well.
OK---operation is as follows, READ CAREFULLY! When power is applied, since the relay contacts are closed, the current goes through the ballast, then through the relay coil, into one end o the lamp, through the cathode filament, then back to the ballast, through the closed contacts, then back to the opposite end of the lamp, through the cathode filament, and finally to the neutral side of the line. this starts to preheat the cathodes, but only for a tiny fraction of a second, as the current going through the relay coil on it's way to the lamp magnetizes the coil, and the armature is attracted and pulls open the starting contacts. This breaks the circuit, and the ballast delivers, along to a certain extent, also the relay coil, too, an inductive kick to the lamp, but it doesn;t start because the insanely brief period of preheating before the relay opens is not enough to fire the lamp, so the contacts close again, and it repeats again and again, the cathode filaments gaining a little more heat with each contact, and the ballast and relay coils inductive kicking the lamp in between each brief contact during the contacts open phases. When enough heat is gained in the cathodes, one of the inductive kicks starts the arc and the lamp is in operation. Since the current has to go through both the ballast and the relay coil, the normal lamp arc current is sufficient to keep the relay coil magnetized, holding the starting preheat contacts open for as ling as the lamp is on. on turn off, the contacts again close by the spring in the relay, ready to repeat the cycle. On a cold lamp it can take between 2 and 4 seconds to start and the relay buzzes like an old door buzzer. After the lamp is warm, the starting is instant, since less preheat is needed, and then the relay only buzzes less than a second, and a near instant start occurs. So--my unit at turn on goes ZZZZZT! the "T" at the end is the relay armature hitting and staying there as the lamp lights. A hot Start is ZT! or even CLICK! Some of the early mag Aux ballasts had a high inertia armature so slow the buzz down to a series of clicks, to get a longer preheat period. others buzzed like mine does. The high inertia relay models went "click click click click click cliT! and a hit start was CliT! The first fluorescent lights ever seen in history by masses of people were in the Emerald City in The Wizard if Oz, from 1939, in the green emeralds. some were likely incandescent too. The Mag aux ballasts would start a lamp instantly once the lamp was warm, so the flashing for this part of the movie was easily achieved using green MAZDA F lamps, which had the saturated color and bright light needed for maximum effect in the movie!
Now--there is another ballast type from this era as well, of which I am up to 4 so far in me collection, all working, in early desk lamps from late 1938 to early 1940 era. This is the GE (and other brands too) Thermal Auxiliary type ballast. these were popular for smaller unite with little space for ballasts, such as in desk lamp bases etc. Instead of a magnetic relay as a starter in the ballast case, and instead of a large, heavy 4 coil ballast choke, this model has a small, single coil, relatively high loss choke, for compact size, and an equally small and compact thermal switch relay. instead of the relay having a magnetic coil in series with the lamp, as in the Mag Aux above, it has a heater coil--a resistance type heater, in series between ballast choke and lamp. It also has the normally closed contacts, but they are thermal type--bi-metallic strip and a stationary contact. When power is applied, due to the thermal mass and heating time of the heater coil in this relay, the lamp cathodes heat up and glow, and since the starting current through the cathodes is rather high, the coil heats up fast, and heats the nearby movable bi-metallic strip, which bends and springs the contacts open, exactly like the ones on a glow starter do, and the ballast inductive kick then starts the lamp, usually and almost always first try. Then, the normal arc current flows through the ballast, heater coil, and lamp as above for Mag Aux ballast, and the continued flow of current keeps the coil and bimetallic switch warm, so the lamp continues to operate, the heater in series with it keeping the bi-metallic contacts open until the lamp is turned off. On restart, there is a delay, in my ballasts it ranges from as little as a half second to upwards of 15-20 seconds, because the bi-metallic has to cool down and reclose the preheat contacts, and the starting cycle repeats. In fact, this internal to the ballast starter switch is identical in operation and design overall to the FS-100 thermal switch 4 pin starters for 85, 90 and 100 watt T-17 fluorescent lamps, and also the now bokoo rare FS-44 4 pin, in the same large can as the FS-100, starters for F40T12 lamps. This starting switch is in a little cardboard cylinder buried in the ballast potting. The specimens I have are 2 GE's, in separate desk lamps, a very early, 1938 Garfield, made for Garfield Electric Co. by GE, and re-badged Garfield, and a rare Dongan Electric unit made under GE patents. The Dongan is in a stellar 1939 Lumidor desk lamp!
I should mention the third type of built in starter ballast made only 2-3 months in 1939---The Westinghouse "Glow Auxiliary" ballast, which uses the very first glow switch starter. The ballast has a simple choke inside, like the 2 above, probably a single coil lightweight compact higher loss model, and a double contact candelabra bayonet socket in one ballast end plate, with a little bayonet S-6 shaped bulb like a car #1004 type bulb, and the same 4 wire layout---2 to this bulb, and 2 to the ballast choke, but no extra coils in this one, the ballast wired straight to the lamp as is usual. It starts EXACTLY like a regular modern glow starter, because it IS one. Westinghouse developed the familiar 2 pin cartridge type starter soon after, so this bulb type starter and ballast set up had a very short run. The starter bulb was called the "GB-1" starter. It was replaceable. the Thermal Auxiliary starter relay and the Thermal Auxiliary starter relays were NOT---if they failed the whole ballast was replaced. I have this Westinghouse ballast and starter in my collection part of a special type of Lumidor desk lamp with a really tall column to the reflector for industrial applications. the ballast works perfect, and in fact has almost no hours on it. this lamp came with 1939 Westinghouse MAZDA T-12 BLUE lamps with the early "vertical" etches, both unused, and having nickel plated brass bases which are pritine and new still. There was the lamp that came in the desk lamp, too, a 1940 Westinghouse MAZDA T-8 White lamp, with super low hours, but used in this lamp, and probably a replacement, perhaps for one of the blues, which could have been 3 in number but one burned out? Who knows! I cannot get the GB-1 put, the damned contact pins in the British-style bayonet socket have indented the solder blobs on the lamp contacts, so it is "locked" in!
Ahh well, at least it works perfect and there is no need to remove it---it has an outside etch of the older circle W with no dots logo, and "GB-1" around the top of the circle W logo. The whole thing is pristine! I have a video clip of it working as well as my nag aux ballast, and the thermal aux units in the desk lamps--once i figure out how to do this with an SD card, i can upload them someday soon. The GB-1 has neon and glows red, but is partially silvered so it is kinda hard to see. I hope this clears up these ballast types, and the starting characteristics! I am still looking for a Magnetic Auxiliary ballast and will get one someday soon, I hope! I already have the other ones! The Mag Aux ballasts, for some reason, seem to be impossible to find these days! Cheers! Rick "C-6" Delair!