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It’s a 194 automotive light bulb that someone put foil around for whatever reason, we’ll probably never know,…..where was it located?…in the front or the back?…..somebody’s carefully taken the time to bend down the finger contacts from the bulb, and solder wire leads to them…..certainly not stock to my knowledge, ……did you just acquire this engine off that unmentionable auction site??…i seen it listed with all kinds of weird add on thingamabobs all over it,….it was listed as a problem child as I recall,….

Pat

@harmonyards posted:

It’s a 194 automotive light bulb that someone put foil around for whatever reason, we’ll probably never know,…..where was it located?…in the front or the back?…..somebody’s carefully taken the time to bend down the finger contacts from the bulb, and solder wire leads to them…..certainly not stock to my knowledge, ……did you just acquire this engine off that unmentionable auction site??…i seen it listed with all kinds of weird add on thingamabobs all over it,….it was listed as a problem child as I recall,….

Patw

It is located at the back of the engine. Not sure why. Yes, acquired it off Ebay. Wasn't running but I figured out the problem tonight. No ground to the motor. Pretty simple. No weird add-on things on this loco. No signs of wear. Tender axle needs attention but other than that a practically new unit.

Beings this is a J3a Super Hudson, 3rd Rail installed driver lights above the drivers,….the Super’s that 3rd Rail molded were unshrouded Dreyfuss Hudsons, that would have had their driver lights left in place after the shrouds were removed…..roundhouse crews used the lights as work lights, and were happy to keep them…..Henry Dreyfuss had the drivers illuminated on his streamlined design to show off the mechanics in motion ……I bet that’s what they we’re trying to keep constant lighting on with that Tomar set up Dave referred to,…

Pat

@harmonyards posted:

Beings this is a J3a Super Hudson, 3rd Rail installed driver lights above the drivers,….the Super’s that 3rd Rail molded were unshrouded Dreyfuss Hudsons, that would have had their driver lights left in place after the shrouds were removed…..roundhouse crews used the lights as work lights, and were happy to keep them…..Henry Dreyfuss had the drivers illuminated on his streamlined design to show off the mechanics in motion ……I bet that’s what they we’re trying to keep constant lighting on with that Tomar set up Dave referred to,…

Pat

Actually, to your point, there are separate lights mountd over the drivers.  Two on each side. Thanks for the explanation. Didn't know why these lights were there.

I remember the Tomar Constant intensity lighting kits from my HO days in the 80s.  I did a little web searching,  but every link to the circuit is a dead link (where old technology goes to die . . .)

Anyway I sketched the circuit here (ignore the diode part numbers) :

Screen Shot 2022-12-04 at 6.31.19 PM

The idea is that each diode drops 0.7v, so you get a constant 1.4 volts differential across the pair, enough to light the 1.5v incandescent bulb in the loco headlight (or up to 4 bulbs according to Tomar in parallel, eg. in a passenger car).  This was designed for variable DC track voltage. The 1.5V lights fully as soon as you apply transformer power (transformers usually jump from zero to a few volts), then the 14V ballast bulb gradually gets brighter as you increase the voltage.  The reason for the 2 sets of diodes was for the polarity change when you changed loco direction.

It was a pretty simple solution but it did create 2 problems:  Light and heat.  That is the reason for the silver tape (and the suggestion to add a 2nd 14v bulb in series so each bulb burned cooler).  I seem to remember people occasionally complaining about melted HO loco shells.

Since this was posted on the 2-Rail forum, I would assume that this is a conventional DC locomotive, thus the use of the same technology as DC HO.

GRJ's constant intensity modules are a vast improvement, don't you think?

Bob

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  • Screen Shot 2022-12-04 at 6.31.19 PM
Last edited by RRDOC
@RRDOC posted:

I remember the Tomar Constant intensity lighting kits from my HO days in the 80s.  I did a little web searching,  but every link to the circuit is a dead link (where old technology goes to die . . .)

Anyway I sketched the circuit here (ignore the diode part numbers) :

Screen Shot 2022-12-04 at 6.31.19 PM

The idea is that each diode drops 0.7v, so you get a constant 1.4 volts differential across the pair, enough to light the 1.5v incandescent bulb in the loco headlight (or up to 4 bulbs according to Tomar in parallel, eg. in a passenger car).  This was designed for variable DC track voltage. The 1.5V lights fully as soon as you apply transformer power (transformers usually jump from zero to a few volts), then the 14V ballast bulb gradually gets brighter as you increase the voltage.  The reason for the 2 sets of diodes was for the polarity change when you changed loco direction.

It was a pretty simple solution but it did create 2 problems:  Light and heat.  That is the reason for the silver tape (and the suggestion to add a 2nd 14v bulb in series so each bulb burned cooler).  I seem to remember people occasionally complaining about melted HO loco shells.

Since this was posted on the 2-Rail forum, I would assume that this is a conventional DC locomotive, thus the use of the same technology as DC HO.

GRJ's constant intensity modules are a vast improvement, don't you think?

Bob

It is a coventional DC loco but will be changed to DCC soon.

@ThatGuy posted:

Why would you want to go back to incandescent, with the complete catalog of LED bulbs now today?

Obviously I wouldn't, just commenting on the fact that I hadn't run across those in my travels.  I am aware of using diodes to regulate the 1.5V for lighting, the MTH PS/1 1.5V directional lighting outputs used the same technique with diodes..

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