MTH 30-11035 1 over 1 signal

The yellow aspect is an internal control.  Using a control rail to activate a relay is very easy. Below are some pics of what you need...

Martin, thanks for the response.  I am familiar with the bridge rectifier - relay hookup using a control rail.  It works flawlessly with a three discreet color head signal.  In that unit, the yellow is somehow internally connected to the green wire for a short time (timer circuit?).  The 1 over 1 signal only produces a yellow aspect if I connect both the red and green wires together to one side of the AC - other side being "ground" AC (if there is really such a thing).  Using a relay effectively eliminates the connection by switching from red to green and vice versa.  I can use the signal with just red - green aspects with no problems - I think I'll have to be happy with that.  Thanks, again.

Buzz 1472

Here is a link to the instructions.

Instructions

Red is connected to Normally Open, Green is connected to Normally Closed and Black is common.  There is a delay when it changes from red to green where it will show yellow or when you first power up.  If it does not then you have a bad signal.  It is the same for any MTH signal, when it switches from red to green it will show yellow for a period of time.

I would need to see how you are using control rails to accomplish this, I can't visualize it.  You need to use a relay because you have to supply power to the lights.

Gene Anstine

Don't connect the red and green together and see what happens,  It sounds like this is a bi-color LED...

Marty

Is that a typo on the MTH number?  From what I can tell the 1 over 1 is really 30-11025:

Assuming we're talking about a bi-color LED, the timing circuit should light both the Red and Green LED (making Yellow) for 10 sec when power is initially applied to the Green wire.  After 10 sec, the circuit should then light just the Green LED.  Applying power to the Red wire should light just the Red LED.

In your case it appears applying power to the Green wire immediately lights only Green, it appears you have a defective timing circuit.  As it sounds like you are familiar with bridge rectifiers and such, you might consider some DIY troubleshooting.  The MTH timing circuit is fairly simple using the venerable 555 timer IC chip.  Schematics have been posted on OGR for the stock and customized versions.

Good morning Marty and Gene,

Thanks for the replies.  Marty, I only connected the red and green leads to check if yellow was even present in the signal ... confirmed it was.  I checked the LEDs and, indeed, you are correct ... bi-color LED ... red, green and return.  So, internally a switch (timing circuit?) must allow both segments to light thus giving yellow.  This would only happen at startup and switching to green from red.  I have observed the brightness of the red LED increases at times when the yellow aspect should be showing.  Based on your input and that from Gene I am concluding I have a defective signal.  Gene I use the control rail as the AC "ground" side a full wave bridge rectifier ... the "hot" comes from a 6A 12V transformer using the + and - DC outputs to control only the relay solenoid.  The AC power to the signal is supplied by the transformer, not track power.  This works because I have all AC power to the layout "in phase".  My hookup works for the MTH 30-11036 signals I have and also for an old Lionel signal bridge I use.  I will swap out the 1 over 1 for a 30-11036 vertical signal as two aspects are not needed where it is placed.  Many thanks for you collective help. 

Best,

Buzz

Good Morning, Stan,

Your comments were posted while I was replying to Marty and Gene.  You are correct ... I earned a "fat finger" award.  I will search out the schematics for the signal and try to troubleshoot it.  After thinking about it, I may have a simple case of two wires touching around the 555 timer area in the signal.  I'll see what happens.  Thanks for the thoughts.

Best,

Buzz

Here's one example of an MTH signal schematic initially posted by member Fec_fan.  When power is applied to Red wire, the Red LED is driven always.  When power is applied to Green wire, the Yellow LED is driven for 10 sec...then the Green LED turns on until power is removed from Green wire.

I can't find the exact schematic to drive a 3-terminal Red/Green bi-color LED but I'd think the circuit is similar.  In the schematic above, none of the LEDs share a connection to a common point.  On the other hand, a 3-terminal bi-color LED shares a common connection (common cathode example drawn above).  Since your Red LED apparently "brightens" for 10 sec when power is first applied to both Red and Green wires, it seems the timing part of the circuit is working.  So as you say, it could be a hopefully easy-to-find wiring short or the like.

If someone gets energetic, I'd like to see the circuit for the MTH Pennsy style 7-light signal.

These don't seem to weather long, our club layout has seven or eight, and only one is still working!   I'd like to do something a bit more robust to replace whatever they used.

gunrunnerjohn posted:

These don't seem to weather long, our club layout has seven or eight, and only one is still working!   I'd like to do something a bit more robust to replace whatever they used.

Did they all fail in the same way?  Being summer-time does your club have summer interns?  

This was the kind of project we'd assign to a summer intern back in the day...

My luck with summer interns doing anything that required thought was never that good.   They always wanted to do "real engineering".  You can probably guess what I told them...

John,

I believe they all use same circuit.  The Pennsy signal has two LEDs for the Red (Horizontal), Yellow (Diagonal), and Green (Vertical).  The center light is on all the time and not controlled by the circuit.  I had one where the center was the only LED lit.

Do you have an idea where they are failing?  I have three bridges and five signals that have been used for about fifteen years and only had that one head fail.  I'm using old Dallee current detectors to control the signals and power them with 12v out of a transformer.

Gene Anstine

I suspect the 18V track power is what kills them.  We should run 12V all around for the signals, but that's a lot of odd wiring for a modular club layout.  Of course, they're supposed to run on 18V, so they shouldn't be croaking!