Wiring a 450 Signal Bridge

[lionelsoni]

The problem is that the point that I labeled "signal common" is the same for both signal heads on the bridge, whereas each signal head's common needs to be connected to a different control rail.  So you need to isolate one of the heads from the bridge.  Then the bridge continues to serve as the common connection for the other signal head and gets connected to its control rail, while a new wire that you connect to the now-isolated signal head gets connected to its control rail.

Of course, you can isolate both signal heads from the bridge if you like and add a new wire to each one.  This would prevent operation of one signal if the bridge accidentally gets connected to the transformer common, perhaps by a derailed train crashing into it.  But there's really no harm in that.  (The accidental operation, not the crash!)

You can hide the extra lamps.  (Remember that you need one for each signal head.)  Or, you can use them somewhere on the layout to light something up, perhaps a billboard or a floodlight tower.  Most observers won't notice that some unrelated accessory lights up at the same time that the signal goes red.

[srguy]

Thanks Bob ... I'm assuming that this diagram is for the 153.  If I go with the 450 and somehow isolate the second signal, will this diagram apply to the isolated signal as well or will another ground be necessary?.  Also, what are you using to house the # 57??? Would you locate under the board??

Jim

[lionelsoni]

accessory
voltage----------------
(or center  |         |
 rail)      |         |
           ---       ---
          /   \     /   \
         |extra|   | red |
         | #57 |   | #53 |
         |lamp |   |lamp |
          \   /     \   /
           ---       ---
            |         |
control     |         |(signal
rail------------------| common)
                      |
                      |
                     ---
                    /   \
                   |green|
                   | #53 |
                   |lamp |
                    \   /
                     ---
transformer           |
commmon               |
(outside---------------
 rails)

[srguy]

You wouldn't happen to have a wiring diagram??

[lionelsoni]

The method I described uses the single contact to the control rail to turn off the green, by shorting out the green lamp, and turn on the red, by connecting the red lamp across the supply voltage.  It's really a very simple circuit and uses no extra electronics, except for a single additional lamp per signal head.

[rtraincollector]

srguy

I'm considering adding a 450 signal bridge to the layout but do not want to use Lionel contactors. I have succesfully used insulated tracks on other accessories but it appears that the signal bridge is more complicated from what I've been able to find on the net.  Can anyone provde a wiring diagram using insulated track and any other components required??

Trying to figure how to get the green to go off and then just let the red come on. using the contactors where when the pressure of the engine comes it disconnects from the up position which would be green and connects to the bottom which turns on the red the only problem I see is you need the green to get turned off when you get to the isolation area of the track so the red will come on or you will have both on when you get to the part the red come on in the isolation track area. Thats the reason lionel uses the 153C to do this and to do it as dual tracks you could use 2 to do this one for each side.

[lionelsoni]

It's entirely your choice, whether you want to insulate one of the 450's signal heads or change to individual signals.

I don't have a 450, so I don't know how the heads are attached.  I can imagine something like replacing a metal screw with a nylon one.  Can you or someone else show us how they go together?

[srguy]

Sounds complicated for the 450 to work properly. Would a newer Lionel #14093 Single Signal Bridge or 153 block signal be a better option??

[lionelsoni]

There is a simple way to operate a signal from a control rail, which I have described a number of times on the forum, using only an extra incandescent lamp.  Here is a description based on an individual 153-type signal:

Connect the green lamp's terminal to the layout common, that is, the outside rails generally.  Connect the red lamp's terminal to the supply, whether the center rail or a separate accessory supply.  Connect the signal's common (the terminal connected to both lamps) to the control rail.  Then connect an extra lamp in parallel with the red lamp, that is, effectively between the supply and the control rail.  The extra lamp should have the same voltage rating as the signal lamps but draw twice the current.  When the signal lamps are number 53s, as they often are or could be, a number 57 is ideal as the extra lamp.  An alternative is to use two extra lamps in parallel, of the same type as in the signal.

This arrangement is not possible for a signal bridge, since there is only one common shared between the two signal heads, which is the bridge structure itself.  You would have to isolate at least one of the signal heads from the bridge so that you have separate common connections to the two heads.

A couple of hears ago, I was surprised to come across almost the same idea in an old book I was reading.  [Raymond F. Yates, Making and Operating Model Railroads, D. Appleton-Century, New York, 1943]  It was attributed to Albert C. Kalmbach, the founder of the very company that sponsors this web site.  The difference was that he used an ordinary resistor in place of the extra lamp.  Lamps work much better in this circuit because the current that the lamp draws varies as the .55 power of voltage, not proportional to it as with a resistor (Ohm's law).  So the voltage across the lamp increases almost as the square of the current.  The number-53 lamp draws 120 milliamperes at 14 volts; so putting a number 57, which draws twice that, in parallel with the red lamp means that the red lamp gets only 1/3 the current that the green one does when they are in series.  Because of the near-square-law behavior of the incandescent lamps, that means that the red lamp gets only about 1/7 the voltage of the green lamp, or about 1/8 of the total voltage.  Furthermore, since an incandescent lamp puts out light proportional to the 3.5 power of voltage, the red lamp in that circumstance is only about 1/1000 as bright as the green one.

[srguy]

I'm considering adding a 450 signal bridge to the layout but do not want to use Lionel contactors. I have succesfully used insulated tracks on other accessories but it appears that the signal bridge is more complicated from what I've been able to find on the net.  Can anyone provde a wiring diagram using insulated track and any other components required??