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Marker lights in Atlas H16-44 switcher for non-OEM decoder install

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Marker lights in Atlas H16-44 switcher for non-OEM decoder install
Posted by tstage on Sunday, May 12, 2019 12:59 PM

Greetings,

I'm tackling another lighting project. Stick out tongue

I have an Atlas H16-44 switcher that I removed the OEM (Lenz) #345 decoder from and installed a TCS A6X decoder because I didn't care for the motor-control of the original decoder.  The replacement A6X works great but the original decoder allowed for switching the directional bi-color marker lights on each end of the locomotive from red-to-green and back.

I'd like to add the marker light function to the A6X decoder but I'm surmising that this may take a bit of custom circuitry work to accomplish that?  From the #345 decoder manual downloaded from the Atlas site, it states the following on pg. 3 (underscoring mine):

Decoder outputs C and D are designed to control the bi-color LEDs used for the front and rear marker lights in these locomotives. Decoder outputs C and D are auto-reversing so that the bi-color LEDs show green in the direction that the locomotive is traveling and red in the opposite direction. The only control over these marker lights is on or off. By default, function F2 is used to turn these lights on or off.

From looking at the original decoder PCB, there appears to be a built-in circuit with several (five) diodes on the left side:

A set of two 3-pin bi-color LEDs is shorted together and soldered to three separate soldering pads at the upper left and lower right corners of the board.  There's also a 4 MHz(?) quartz crystal oscillator at the upper right corner of the board that's connected to a 20-pin IC and a sizeable cap to the left of the IC.  I don't see anything similar to that on the A6X.

Is this something that is reasonably doable for the A6X?  Is there a simple circuit that I can fabricate to switch the polarity of the bi-color LEDs, add it to the AX6, and have it change color when pressing a given function button?  Or, does this seem pretty involved for a DIY?

Thanks for the help...or for any sobering reality.

Tom

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Posted by rrinker on Wednesday, May 15, 2019 8:02 PM

 If you remember to only turn one function on at a time, and use 3 lead style bicolro LED< you couold use two functions outputs, one for red and one for green. 

Better yet, find bicolor LEDs with white and red, since green is mostly useless.

                             --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by gmpullman on Wednesday, May 15, 2019 8:33 PM

rrinker
Better yet, find bicolor LEDs with white and red,

LED-Switch has some 3mm common anode white/red LEDs:

http://www.led-switch.com/3mm%20LED.htm

With a good eye and steady hand you could make up your own SMDs as, I seem to recall, Mel did for signals. I found some R/Y/G clusters but I don't recall at the moment where, maybe it was Evan Designs?

Good Luck, Ed

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Posted by tstage on Wednesday, May 15, 2019 9:08 PM

rrinker
Better yet, find bicolor LEDs with white and red, since green is mostly useless. --Randy

So, red/green would not have been prototypical?

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Posted by rrinker on Wednesday, May 15, 2019 10:42 PM

Well, red is used as a marker for a loco runnign light (on the rear) or on the rear of a train. Green is for multiple sections - almost never happens with freight trains and MAYBE if you were running passenger traisn with that loco it could happen. WHite means running as an extra - which on many roads, most freights were, only a few were scheduled. So a white and red mix is MUCH more useful on a mostly freight loco than red/green. 

                   --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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