Here's the product. A fun little project. (The handrails were a bit of a struggle.) Thanks for the various tips and suggestions.
Paul
Modeling HO with a transition era UP bent
I plowed ahead today and simply rerouted the NW2 rear light wiring to the new calf LED. My bias became, since the units are wired together, they consist just fine as the SW2 forward mode still lights its headlight, and when they are in reverse the calf light goes on. Much like an A-A consist would normally work. It was interesting to pursue the options.
I had not thought of checking voltages as Mark suggested. But the cab circuit had the least interest for me as I did not want to use POM CV adjustments just to turn a light on or off.
I'm now adding the handrails (had to get some 0.022" wire to make some missing ones. Will be all done tomorrow.
I think I'll enjoy the switcher-calf combo. I keep finding items of interest that I did not know were produced, such as this older Athearn dummy calf.
Did you try putting a new LED in parallel with the one in the cab ? If the resistor is on the board, it may just work. If the resistor is attached to the cab LED, then you're just out one LED for trying ....
If you have a meter, test the voltage where the LED is attached to the board. If it is around 12 volts, the resistor is up-stream. If it's around 3 volts, the resistor is on the board.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
peahrensDid the prototype lights tend to work automatically with direction change, or did the crew sometimes just pick which lights to have on/off or leave on rather than throw switches with each direction change?
The engineer would turn both lights on dim and we would go about our work.Some yard engineers didn't turn them on at all during daylight-unless somebody said something about it.
As a side note none of the engineers I worked with on the PRR or Chessie would sound the bell or horns with every direction change-it was a "good neighbor" policy only because it cut down on the noise complaints.
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
peahrens Bob, that would triple the project cost from 3 cents to 9 cents. And if the cab light also changed I'd be into double digit territory.
Bob, that would triple the project cost from 3 cents to 9 cents. And if the cab light also changed I'd be into double digit territory.
Maybe you could sell the old LED's and recoup some of the cost? You can sell anything on Ebay! LOL!
-Bob
Life is what happens while you are making other plans!
Just a thought on getting LED's to match: just replace all of them with one you like. This may require unsoldering from the board but it isn't ususally that much trouble.
Lights in the prototype only change when the headlight switch is changed by the crew., they don;t automatically change direction. Nor do they automatically dim when the loco stops. On switch engines it was common to have both lights on all the time - but if you want to be absolutely accurate you should probably consult the rulebook for your prototype, or if you are freelancing, pick one and style your rules after a real one.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I found some additional info that relates to "easy" Plan B alternatives:
B1) I could give up the NW2 rear headlight and wire that output to a LED in the calf (which will face rearward). So when backing the consist only the calf light would shine.
B2) I could give up the independent cab light (hardly can notice it anyway) and wire that output to the calf new LED. The BLI cab light can not be turned on/off with a function button (and I see no info on how to map it). Instead, it has an adjustable CV that (default is 3) can be set at 0-255, such that the cab light is lit below the speed step of the CV. At default, it is on when stopped or moving forward / reverse up to step 2 or 3. I could set the CV high (255), such that the calf light would always be on. (I would not bother to turn it on and off with POM and changing the CV, unless I wanted it off when parked).
I prefer to go with one of these options as they are pretty easy. It comes down to what is more prototypical and knowing a bit about light control capabilities and practice in the prototypes. Option B1 would have the NW2 forward light respond with direction change (and the NW2 rear light not work when in reverse). Option B2 would have NW2 forward and reverse lights work directionally, and the calf light always on (including when the NW2 was going forward.
Comments please. Did the prototype lights tend to work automatically with direction change, or did the crew sometimes just pick which lights to have on/off or leave on rather than throw switches with each direction change?
Thanks, everyone!
UPDATE: I got the BLI open and cut a back light wire and tried a 3mm LED in series. The twin LEDs would not light (they are both good when tested) so i presume there is not enough voltage with whatever resistor is on the BLI board for the two to activate. Yes, tried the new LED in both directions. The existing wires for the rear light go into a plug, and I can't see on the circuit board where the pre-resistor voltage could be picked up.
So this will require a Plan B. The only easy way would be to bypass the loco rear light and use that wiring to the calf light, so only that would come on when the pair ran in reverse. Alternately, some kind of decoder plus metal wheels in the calf just to have a light function. I really don't care if it's motorized.
I'll have to consider all this. Think I'll watch the PGA.
Alternately you might look into NWSL Stanton drives (motor in truck) for your calf to make it not a dummy. You could then add a motor only decoder or sound if you want. Additionally you could replace the wheelsets in the calf with metal ones and draw power from the track with wipers. Then add a function only decoder (can you consist a function only decoder with a dcc decoder?).
Stanton drives are somewhat expensive route, $85 for powered, $45 w/o motor.
SW-7 shell removal: First you need to carefully pull the two handrails that run from what appears to be a battery box to the frame (not the ones by the cab door). The hood then is removed by squeezing the base of the hood near 2 sets of tabs, one pair is directly above the front truck. The second pair is directly above the front wheel of the rear truck, or dead center of the taper back to the cab. If you have not looked at a paragon 2 decoder you will be in for a small shock (not color coded and everything uses 2 or more wire plugs). Nice but pain if you want to modify.
Paul,
Once you get the shell off, with most switchers the lighting is right at the top of the hod end and easy to get to there. The cab end light can be trickier, but you'll likely want to tap in there before the circuit goes up to the cab roof.
Yes, you can play with resistors and try to get a series circuit to work. Often, the mfgs make headlights a little too bright, so dimming the original isn't bad thing if you do mod it. Keep in mind you may also want to try to get the headlight at the other end adjusted to match, too.
The problem you'll find is getting the LEDs to match (for starts) when on exactly the same power in parallel and then finding resistors that together keep that match. It is possible, but might be a bit frustrating until you get it right. Resistance calculators can account for the resistors, but usually AFAIK don't account for the LED output differences you'll likely see in practice.
Mike Lehman
Urbana, IL
Thanks, Mike. I'll see if I can locate the 12v supply to the cab light upstream of its resistor.
I played with the LED calculator below, which I had forgotten about and presumed it only handled one LED, but it also handles multiples in series or parallel. Assuming 12v supply, 2.5v LED drop and 10ma current per LED, the LED would want a 950 ohm resistor. If two LEDs in series, the resistor required would be only 700k, indicating some dimming as you suggest. If two in parallel, since the current goes up for two LED paths, the resistor value goes down to 475.
http://ledcalc.com/#calc
So the best approach is to get to the 12v power of course. If I can not figure out how to get the 12v (pre-resistor) cab light power I could try the series approach and see if they are too dim. The parallel approach is not easier and a worse result I now see. Interesting.
Plus, I hope I can figure out how to get shell off the loco.
You don't want the LEDs in series, as that would substantially dim the output you're getting currently in the mother loco. You can run an extra pair of leads from the output and ground used on the mother's headlight. I would use the full power before the resistor to the mother's headlight to run to the "calf" then add a separate resistor to that circuit. Use the same resistor value as the original and they should be close, depending on how well you can match the second LED.
I got an old Athearn dummy calf that I plan to run with my BLI Paragon 2 NW2. I want to add an LED headlight to the calf, powered by the cab end NW2 headlight so that both come on together when in reverse.
I'm assuming that the BLI has LED lights (have not looked inside yet) with a resistor either on the circuit board or in the lighting wiring. Let's say the resistor is on the board. If I want to add the 2nd LED in parallel to the existing, I'm not clear on what that does to the current and voltage, requiring additional resistors for each LED, etc?? Or can I run the LEDs in series?? This is beyond my understanding.
Any suggestions are most welcome.