How to drop from 18 volts to 14 volts from track power to operate trackside signals

Take two bridge rectifiers and wire the + to the - for each one.  Then wire the ~ terminals in series with the hot lead, they'll drop about 3.5 volts.

I'm sorry, John.  I'm not that electronically savvy.  What type of bridge rectifier is needed? 

Wire your accessories to a different transformer and set the voltage where you want.  Small ones are cheap and it is always best not to have that extra draw on the track.

@Bill DeBrooke posted:

Wire your accessories to a different transformer and set the voltage where you want.  Small ones are cheap and it is always best not to have that extra draw on the track.

I'm using the track as a switch to activate, so voltage must be drawn from the track and not another transformer.   I also don't want to use the Infrared track activation devices that Lionel and MTH make either.

@gunrunnerjohn posted:

Take two bridge rectifiers and wire the + to the - for each one.  Then wire the ~ terminals in series with the hot lead, they'll drop about 3.5 volts.

I'm sorry, John.  I'm not that electronically savvy.  What type of bridge rectifier is needed?

@trainmanmason posted:

I'm using the track as a switch to activate, so voltage must be drawn from the track and not another transformer.   I also don't want to use the Infrared track activation devices that Lionel and MTH make either.

This is not actually true, I use isolated track sections to operate my automatic crossing gates and my automatic gateman. I use a separate power source for them, not track voltage. I'm using a 14v supply for the same reason, 18v track voltage is to much, they work better at 14v.

I assume that the insulated track section you are using insulates the outside rail. If so, you can use two transformers, one for the trains, one for the accessories. You will need to get the two transformers in phase. Search for this on this web site.  There are lots of posts addressing phasing transformers. Just a mater of plugging the plug in to match its other transformer. Then connect the common terminal terminal of both transformers to the outside rails. The 18 volt transformer connects the other wire to the center rail fit the trains  and the 14 volt transformer goes to one side of the accessories. The other side of the accessories goes to the insulated outside rail. When the axles connect the uninsulated rail to the insulated rail, the circuit is complete and the accessory will be energized.

@trainmanmason posted:

I'm using the track as a switch to activate, so voltage must be drawn from the track and not another transformer.   I also don't want to use the Infrared track activation devices that Lionel and MTH make either.

@Darrell posted:

This is not actually true, I use isolated track sections to operate my automatic crossing gates and my automatic gateman. I use a separate power source for them, not track voltage...

@Darrell, correct, you can even use DC, like from a power pack or even a car battery if you want.

@ADCX Rob posted:

@Darrell, correct, you can even use DC, like from a power pack or even a car battery if you want.

If DC will work how about those Ac to DC buck converters sold on ebay? They are only a couple of dollars each. These have an adjustment screw so the voltage can be dialed in.

@trainmanmason I don't see an email in your profile. Shoot me an email and I can give you the link to the buck coverter. ( ogr doesn't allow ebay links as they are not a sponsor)

@David Johnston posted:

I assume that the insulated track section you are using insulates the outside rail. If so, you can use two transformers, one for the trains, one for the accessories. You will need to get the two transformers in phase. Search for this on this web site.  There are lots of posts addressing phasing transformers. Just a mater of plugging the plug in to match its other transformer. Then connect the common terminal terminal of both transformers to the outside rails. The 18 volt transformer connects the other wire to the center rail fit the trains  and the 14 volt transformer goes to one side of the accessories. The other side of the accessories goes to the insulated outside rail. When the axles connect the uninsulated rail to the insulated rail, the circuit is complete and the accessory will be energized.

I can see this working for the gateman, crossing gates, etc.  How can you get this to work for having a block signal switch from red to green?

@RickO posted:

If DC will work how about those Ac to DC buck converters sold on ebay?

Those work too, but remember that any device connected to the track power source will have to be referenced / phased to prevent shorts while the trip/trigger section is not in use.

Why not just lower the track voltage to 14 volts? You don’t necessarily need 18 volts on the track. Top speeds will be slightly lower, but that’s about it. The locomotives will run fine on 14 volts.

Lots of advice above, but the basic situation is that you started by not understanding how to use an insulated rail method properly. It is never advisable to use track power for accessories, for many reasons.  One reason is the one you've discovered: inability to adjust the accessory voltage accurately.

1. Use two separate supplies (or two outputs from the same supply)

2. Be sure to phase the two supplies or be sure that the two sources from the same transformer have a common return.

3. Search for "insulated rail" operation in this or other forums.

4. The insulated rail switches on/off the common return.

5. To install a block signal with two states, you need to operate a relay that in turn powers the two lamps in the block signal.

@Arthur P. Bloom posted:

5. To install a block signal with two states, you need to operate a relay that in turn powers the two lamps in the block signal.

Relay can be used, but it is not required.

I use ZW and ZW's with bricks and I have some folks telling me that the common should be the center rail and the outer rails should be the power (A,B,C, or D).  And I've heard it the other way, too, that the center rails should be power and the outer rails should be common.

Which is it?

@trainmanmason posted:

I use ZW and ZW's with bricks and I have some folks telling me that the common should be the center rail and the outer rails should be the power (A,B,C, or D).  And I've heard it the other way, too, that the center rails should be power and the outer rails should be common.

Which is it?

The center rail is hot.

The convention (documented in Lionel postwar instructions) is the "common" or 'U' terminal goes to the outside rails.  The A,B,C,D terminals connect to the middle rail or accessories.

@Tracker John posted:

The convention (documented in Lionel postwar instructions) is the "common" or 'U' terminal goes to the outside rails.  The A,B,C,D terminals connect to the middle rail or accessories.

Not for a majority of the single throttle PW transformers, the U terminal is the hot terminal.

Manuals for my 1033 and ZW postwar transformers illustrate the 'U' or common posts connected to the lockon terminal 2 (outside rail). and the A (and B,C,D as provided) posts connected to the center rail.   I won't speculate on the multitude of other postwar models.

My reburbished CW80 (which has since died) didn't come with the manual, so I looked at the manuals on Lionel's support site.  Two versions are available.  The 2/03 manual text says connect the CTC lockon clip 1 (center rail) to the 'A' post, and lockon clip 2 (outside rail) to the 'U' post.  However, the accompanying diagram shows the reverse connections.  This may explain the contention to connect the 'A' (or hot) terminal to the outside rail.

Then 6/08 manual has the same text but the diagram is corrected to show 'A' connected to the center rail and 'U' connected to the outside rail.

It's AC.  I can't think of any design reason why the wiper arm should be connected to either the center or outside rail.  If using a single transformer, the track connection doesn't matter.  If using multiple transformers, verifying transformer phasing is necessary and following consistent wiring conventions is recommended.

I found, common HO transformers, were abundant, and easy to use for (Accessory voltage)(DC) Some have AC.

@trainmanmason posted:

I'm sorry, John.  I'm not that electronically savvy.  What type of bridge rectifier is needed?

Is there anybody out here that can build 17 small modules that can be placed next to the MTH Railtrax switch connectors (  red , green and black wires ) to convert the track power down to 14 volts from the DCS / TIU  /  Z1000s  ?   Not savvy here either to know if it would work !?!

Layout has too many switches in too many directions to do a rewire from the accessory panels on the Z1000s .

I thought this might help.....

@Tracker John posted:

Manuals for my 1033...  ...illustrate the 'U' or common posts connected to the lockon terminal 2 (outside rail). and the A... connected to the center rail.   I won't speculate on the multitude of other postwar models.

That would be in error. There are conflicting diagrams over the years, but "U" is in fact the center rail connection for the 1033 and contains the throttle, whistle, and direction controls in its circuit.

@Tracker John posted:

I won't speculate on the multitude of other postwar models.

No speculation needed, there is a rule.

Multi-throttle transformers use "U" as common, single throttles use "U" to the center rail, and another, usually "A", as the common. Several have  alternates for different optional voltage ranges... "B" for the 1033, eg.

You can confirm this by referencing the service literature.

Would it be possible to accomplish the goal using resistors?.

@Don Sierakowski 111617 posted:

Would it be possible to accomplish the goal using resistors?.

I wondered the same thing Don.     It would be great to be able to keep things simple for this application.

I know with the right resistors something can be done with DC voltage say for headlights etc. from a board but not sure what could be done with AC track power's higher voltage.

@Dallas Joseph posted:

I wondered the same thing Don.     It would be great to be able to keep things simple for this application.

I know with the right resistors something can be done with DC voltage say for headlights etc. from a board but not sure what could be done with AC track power's higher voltage.

Sure, a resistor *could* be used for either AC or DC, but you'd need to know exactly what the current draw would be for the accessory being powered, since the voltage drop produced is guided in a linear fashion by Ohm's Law. Also, if you change the current draw (by adding additional accessories drawing through the resistor), you will also change the voltage drop.

For this reason, I've decided to explore using power diodes to achieve a consistent voltage drop (I've been told each diode will drop the voltage by about 0.7 volts) regardless of the accessory's current draw. They are also able to work on AC, if you pair each diode with one with reversed polarity, allowing the full wave through with a consistent voltage drop. Bought in bulk from overseas, such diodes are ridiculously cheap (though still a bit more than plain resistors from the same source). Like I said, this is a new use for me, so take my comments with caution, but I'll post more once I can experiment. Stay tuned . . .

@Steve Tyler posted:

For this reason, I've decided to explore using power diodes to achieve a consistent voltage drop (I've been told each diode will drop the voltage by about 0.7 volts) regardless of the accessory's current draw. They are also able to work on AC, if you pair each diode with one with reversed polarity, allowing the full wave through with a consistent voltage drop. Bought in bulk from overseas, such diodes are ridiculously cheap (though still a bit more than plain resistors from the same source). Like I said, this is a new use for me, so take my comments with caution, but I'll post more once I can experiment. Stay tuned . . .

I'll definitely have to stay tuned Steve.  This sounds interesting.

Each MTH switch wiring would possibly have to be sorted out hopefully at the rail or switch throw.

Thanks Steve.   Hopefully all is going well at Cattail Creek.

@Junior posted:

I thought this might help.....

That's great information for all!!  Thank you!!!

Thanks, Steve.  I will also be interested in your result.  I’m interested in dropping my 18 volt track voltage to 8-12 volts powering Lionel detectors and some signals.  I have some old GOW bulb signals to manage as well…

Wouldn't it be a lot simpler, and cheaper, just to run a 14 Volt bus around the layout, and tap into it where ever you need that voltage?

@Don Sierakowski 111617 posted:

Would it be possible to accomplish the goal using resistors?.

Resistor voltage drop varies with current, if you use diode pairs to drop voltage, the voltage drop is not dependent on current.

@Dallas Joseph posted:

I'll definitely have to stay tuned Steve.  This sounds interesting.

Thanks Steve.   Hopefully all is going well at Cattail Creek.

Yeah, this has been recommended by GRJ among others, and while I have no reason to doubt their wisdom, I just want to see it in action myself and confirm it works as advertised!

As for Cattail Creek, it's still winter bleak but low 40's and sunny, at low tide!

@Steve Tyler posted:

Yeah, this has been recommended by GRJ among others, and while I have no reason to doubt their wisdom, I just want to see it in action myself and confirm it works as advertised!

As for Cattail Creek, it's still winter bleak but low 40's and sunny, at low tide!

Temps and sun about the same as Cattail Creeks out here in north central Pa. along I -80.   🌞🌬

Thanks Steve.