Directional Lighting for MTH Engine

I have a 30-2181-1 ABA set w/prosounds (1?).. It does not have directional lighting, both headlights function all the time.. I don't see a similar connection to the one in the OP's picture.. How do I make directional lighting happen in my application, or can I reasonably do so??

While PS1 had the capability of directional lighting, it was only a 1.5V low current bulb.  With many PS1 ABA setups, the lights were wired all on.  If you really want directional lighting with decent intensity bulbs, you'd probably want to use a 1.5V coil relay, this relay only requires 33ma coil current at 1.5 volts: http://www.digikey.com/product...V/255-3476-ND/650130

Next, you'd have to run the tether back to the trailing A-Unit to operate the lights.  Any tether currently in use probably has all pins allocated, and obviously you would have to pipe back the power for the reverse headlight.

Finally, you'd have to actually switch the direction with the relay.  I'd probably wire the relay coil to the reverse lamp output so the lead headlight would be on in forward and neutral and the reverse headlight would only be on in reverse.

If this is the correct parts diagram from the MTH site:

http://mthtrains.com/sites/def...loded/30dl12231e.pdf

the trailing A appears to have its own powered trucks.  Hard to tell but it appears the rear headlight is just an 18V bulb running from track power? 

Too bad they don't tell you how many wires are on the various harnesses.  Odd MTH would run harnesses thru the B unit to drive the operating trailing coupler but not implement directional headlights?

The tether is indeed a 4 wire unit, but only 2 are used, it appears to only be used for the electocoupler. The trailing A has powered trucks that are only used for the rear headlight as Stan stated.. The fixed connector on the powered A only has the 2 wires for the rear coupler in it.. Is there a four wire harness (37 in the powered A diagram) available from MTH? If so, that would eliminate the additional tether issue.. Then where would I pick up the  electrical signal for directional lighting.. I have LED lighting ordered from Evans Designs, so that would reduce lighting current flow.. It would be simple enough to remove the track power light source in both A units.. Would I still need the relay that John states??

So my questions are: 1. Is there a 4 wire connector available from MTH for the powered A or would I have to fabricate one? 2. Where would I pick up directonal signals in the powered A unit? 3. Would I still need the relay John states and if so how would I wire it? 4. What else is there that I might be missing? TIA You guys are always so helpful!!!

Since the directional lighting on PS/1 is only 1.5 volts, it won't drive any standard white LED, they require 3V or more, and the Evan's stuff will require a lot more voltage.  So the answer is yes, you need some method of "amplifying" the 1.5V light output of the PS/1 board.  You could create a solid state design if you like, I was going for simple for the non-electronic person to easily wire up.

Why do you need a connector, it would seem the tether pipes the wires from the powered lead unit to the trailing unit already.  If you have two free wires, you're certainly home free.

gunrunnerjohn posted:

Since the directional lighting on PS/1 is only 1.5 volts, it won't drive any standard white LED, they require 3V or more, and the Evan's stuff will require a lot more voltage.  So the answer is yes, you need some method of "amplifying" the 1.5V light output of the PS/1 board.  You could create a solid state design if you like, I was going for simple for the non-electronic person to easily wire up.

I guess I need to clarify.. How would I wire the relay into the circuit? What wires would I have to get the 1.5v signal in the A unit from??

Why do you need a connector, it would seem the tether pipes the wires from the powered lead unit to the trailing unit already.  If you have two free wires, you're certainly home free.

The connector on the back of the A unit is a four wire connector, but it only has 2 pins to control the rear coupler, the other 2 cavities are empty.. Can I add pins to that connector? If so where would I get them and what part number would I be looking for""

Woodson posted:

gunrunnerjohn posted:

Since the directional lighting on PS/1 is only 1.5 volts, it won't drive any standard white LED, they require 3V or more, and the Evan's stuff will require a lot more voltage.  So the answer is yes, you need some method of "amplifying" the 1.5V light output of the PS/1 board.  You could create a solid state design if you like, I was going for simple for the non-electronic person to easily wire up.

I guess I need to clarify.. How would I wire the relay into the circuit? What wires would I have to get the 1.5v signal in the A unit from??

Why do you need a connector, it would seem the tether pipes the wires from the powered lead unit to the trailing unit already.  If you have two free wires, you're certainly home free.

The connector on the back of the A unit is a four wire connector, but it only has 2 pins to control the rear coupler, the other 2 cavities are empty.. Can I add pins to that connector? If so where would I get them and what part number would I be looking for""

 

That's odd, but the connector is certainly readily available.  I'm not sure exactly what connector is used on that one, most of the ones I see have all four wires.  Are you talking about the female connector that goes to the B-Unit or the male connector on the powered A-Unit?  I have a ton of the MTH 4-pin tethers, so if it's a standard one, I've got your number.

Pictures will help.

gunrunnerjohn posted:

Woodson posted:

gunrunnerjohn posted:

Since the directional lighting on PS/1 is only 1.5 volts, it won't drive any standard white LED, they require 3V or more, and the Evan's stuff will require a lot more voltage.  So the answer is yes, you need some method of "amplifying" the 1.5V light output of the PS/1 board.  You could create a solid state design if you like, I was going for simple for the non-electronic person to easily wire up.

I guess I need to clarify.. How would I wire the relay into the circuit? What wires would I have to get the 1.5v signal in the A unit from??

Why do you need a connector, it would seem the tether pipes the wires from the powered lead unit to the trailing unit already.  If you have two free wires, you're certainly home free.

The connector on the back of the A unit is a four wire connector, but it only has 2 pins to control the rear coupler, the other 2 cavities are empty.. Can I add pins to that connector? If so where would I get them and what part number would I be looking for""

 

That's odd, but the connector is certainly readily available.  I'm not sure exactly what connector is used on that one, most of the ones I see have all four wires.  Are you talking about the female connector that goes to the B-Unit or the male connector on the powered A-Unit?  I have a ton of the MTH 4-pin tethers, so if it's a standard one, I've got your number.

Pictures will help.

I'm talking about the female pigtail that comes out of the powered A that plugs into the fixed plug on the unpowered A.. Upon closer inspection, all 4 wires are in the pigtail.. I peeled back the outside sheathing a bit and the other 2 wires are indeed there.. They were cut off flush with the sheathing and I couldn't see them.. So that resolves the connector issue (insert feeling stupid Emoji here)... I tried to take a picture but I couldn't get that to show detail.. Thanks for hanging in there with me John!! On to the next questions...

How about

That's if you already have the "universal ac/dc" type of Evans LED already on the way.  So the incremental cost would be $7-8 (with shipping) for the relay GRJ suggested.

As an alternative, if indeed you have 1.5V DC coming from the tether I figured there's got to be an eBay voltage converter module that might apply.  1.5V is the single-cell battery voltage so it stands to reason someone sells a widget to boost that voltage up to drive LEDs say for tiny flashlights and such.  So, for example

So for less than $2 shipped (albeit from Asia) this tiny module would take the 1.5V DC from the tether and boost it up to 5V DC.  This 5V DC could then drive a 10 cent white LED thru a 5 cent resistor.   Or, there are pre-wired (resistor included) white LEDs that can be driven by 5V DC.

The idea here is since the rear trucks apparently only power the rear bulb, you could remove the rollers/wipers since they are no longer needed for power.  This reduces drag on the powered unit so you can pull more cars...which of course was the function of the rear A unit in the first place!

One fly in the ointment here Stan is the current capability of the PS/1 headlight outputs.  I know they drive really small low-intensity bulbs, so I'm speculating that 20-30ma is all they can deliver.  That being the case, trying to boost it with a switcher to 5V isn't likely to happen.  I haven't actually tested the current capability of the lighting outputs of the PS/1 board, I'm just extrapolating on the bulbs that are used in PS/1 diesels.  There are some PS/1 units that feed the headlight output to a separate electronic board with a transistor gate to drive larger bulbs, another reason I think the on-board light output is pretty anemic.  That's the reason I was looking for the lowest power relay that would switch on 1.5V DC, the 33ma model was the best that Digikey had.

Both the headlights in my PS1 are powered in the 'old conventional method: track power only.. No electronics involved.. I traced the power wire in the powered A to a wire nut junction and I measured the voltage to the headlight- track power.. The unpowered A simply picks up it's voltage from the roller pick ups of that unit, totally independent unto itself.. I'm not sure where/if or even feasible to pick up the 1.5v DC reference signal to control the relays..

Maybe my best option is not to worry about directional lighting at this point, install the  LEDs and live with it until I decide to do an ERR upgrade..   Thoughts??

There are two plugs on the PS/1 board for the lights, very easy to connect to them.

The parts diagram shows both front and rear lamps as CG-0000002 which are "Bulb Bayonet Base G 3 1/2 Globe 18 Volt".

Well, even if the long-term plan is to upgrade to some command-control it still seems directional-headlights is a desirable feature.  So I think sending the actual rear lamp voltage (rather than some kind of relay control) is worth pursuing to allow removal of the mechanical pickup drag.

Hopefully someone knows why the two lamp connectors are unused...and if a useful signal is nevertheless present that can trigger a relay or whatever.  But in any event, if it becomes a matter of principle (!) to make it work, you can pick off the on-board signal (probably 5V) that controls the on-board direction relay.   Or a partial solution could be to pick off the motor terminal voltage to determine when the DC polarity is reversed.

Side comment to GRJ.  Given the technology of the day (i.e., no white LEDs), was the "choice" of 1.5V a result of tapping the voltage drop from 2 silicon diodes? 

gunrunnerjohn posted:

There are two plugs on the PS/1 board for the lights, very easy to connect to them.

Thanks for the information John.. Do you know the output voltage of the light connectors? 1.5v? Are these plug in connections or do I need to solder wires to the board? If they are plug in, where do I get the connectors? Can I buy them from you?

"Well, even if the long-term plan is to upgrade to some command-control it still seems directional-headlights is a desirable feature.  So I think sending the actual rear lamp voltage (rather than some kind of relay control) is worth pursuing to allow removal of the mechanical pickup drag."

"Hopefully someone knows why the two lamp connectors are unused...and if a useful signal is nevertheless present that can trigger a relay or whatever.  But in any event, if it becomes a matter of principle (!) to make it work, you can pick off the on-board signal (probably 5V) that controls the on-board direction relay.   Or a partial solution could be to pick off the motor terminal voltage to determine when the DC polarity is reversed."

Both good points Stan!! I'd much rather pick up 5v signals somewhere to control the LED directional lighting if possible.. This would eliminate the need for a relay.. "Somewhere" is the key word here.. Where would that "somewhere" be?? Can I indeed tap into the motor wires?? If so, I would think the reduced current flow to the motor would be minimal and the elimination of the trailing A roller pickups would be a plus,as you already stated..

The two lamp connections will have the 1.5V lighting drive on them, as to how it's generated, the double diode drop is probably a decent guess, I never chased it down. 

If you tap in to the motor wires, you will get varying voltages from 2-3 volts up to 12 or more.  I'd be looking for a place to get fixed voltage.  I don't know if the motor direction relay coil drive would have a common ground, that might complicate things.

Stan must be tuned into old technology, it does seem they're using a couple of diode drops to run the lights.  As the motor current increases (holding the flywheel), the lights get a bit brighter, just like a diode drop with more current increases a bit.  If you unplug the motor while running, the light goes out, even though the board still thinks it's in motion.

If it is confirmed that those two lamp connectors don't provide anything useful for directional indication then I'd go after the directional relay control signal.  The reason I called tapping the motor terminals a "partial" solution is it will only have reverse voltage when the motor is driven.  Whereas I'd think you want the rear headlight on when in neutral-before-reverse...as well as when slowing or momentarily stopping when in reverse.

Per this photo from this OGR thread, there are 2 relays on the power board.

These are undoubtedly for motor control and likely one for direction fwd/rev and the other for on/off.  The markings show JS1-6V which is a common relay (datasheet).  So unless someone can identify another source of directional indication, what I would do is look at the coil voltages on those two relays and see if you get a "steady" voltage in reverse.  I say "steady" because it is common practice (to save power) when driving a relay to lower the applied voltage once the relay has closed.  Per datasheet, that relay will hold closed with less than 1V applied...that could confound any efforts to directly use the relay coil voltage to drive a 3V white LED!

Hmm, this does seem to be getting complicated... but if you're still engaged I can see a light at the end of the tunnel MU.

"Hmm, this does seem to be getting complicated... but if you're still engaged I can see a light at the end of the tunnel MU."

Yes, I'm still trying to figure out what to do.. I haven't been able to get back to it and I'm waiting on some parts.. Thanks for the information!!

The relays are obviously strictly for motor direction.  One engages when in reverse, and one engages when in forward.  Both are inactive when the motor is not running in neutral.  There is about 4.8-4.9 volts across them when they're activated, there is a transistor that drives them.  So, one would presume you could parallel an LED and a resistor across each relay coil and have directional lights, I doubt 15-20ma would affect the relay drive.  They would only be on when the motor was turning.

Too bad neither relay coil is active for neutral-before-reverse.  So be it.  From the same thread I referenced earlier is this additional photo of the power board with relays.  Looks like someone tapped into the two relay coils (blue and brown wires).  Might have been for the same purpose!

I've seen wires hanging off for lights, but since I'm usually ripping the boards out, I never really took close notice.  In order to get lights in neutral, I suspect some logic would have to be added to the lighting.  Probably why I've never seen a PS/1 that offered directional lighting that was on when in neutral.

gunrunnerjohn posted:

I've seen wires hanging off for lights, but since I'm usually ripping the boards out, I never really took close notice.  In order to get lights in neutral, I suspect some logic would have to be added to the lighting.  Probably why I've never seen a PS/1 that offered directional lighting that was on when in neutral.

 

As soon as the LEDs get here, I'm going to give it a shot.. I guess the worst thing that can happen is that I 'let the smoke out of the board' and send it to you to do an ERR upgrade.. lol

You'll just need a series resistor, I'd probably go for 150 ohms with the white LED's.  You'll get a nice headlight that's on whenever you're moving, better than no directional control.

gunrunnerjohn posted:

I've seen wires hanging off for lights, but since I'm usually ripping the boards out, I never really took close notice.  In order to get lights in neutral, I suspect some logic would have to be added to the lighting.  Probably why I've never seen a PS/1 that offered directional lighting that was on when in neutral.

Interesting observation.  I'd think anyone going through the effort to identify the relay coil locations, solder wires, add resistors, mess with LEDs (presumably), etc. would have taken the extra step of adding the circuitry to handle neutral.  But better than nothing.  Plus, tapping the ~5V DC coil voltage to drive an LED gives constant-brightness headlights vs. 18V bulbs connected to variable track voltage.

Presumably, with a simple circuit, you could have the neutral after forward switch the rear lights on, and the neutral after reverse switch the front lights on.  Of course, you could also toss in a regulator to have constant voltage lighting as well.

I'm with you, I'd have made it work in neutral, having the headlight go out when the engine is stopped is low class...