MTH Traffic Light Control

You could use the traffic light controller and integrate a relay to shut off power to the super streets block at the intersection.

Thanks Matt.  When the lights turn red, I could turn off power to the adjacent super street road sections.  I'm guessing the MTH controller can't source the current to energize a relay so I'd most likely need an interfacing driver circuit.

To be clear, are you trying to

a) control the lights "based on super-streets traffic flow."  For example, near me there are traffic signals which automatically turn red when a train approaches a grade crossing near the intersection.

or,

b) control super-street flow based on the traffic lights.  This sounds like what the relay method would do if you're killing super-street power when the traffic signal is red.

In either case, if relays are part of the solution, most of those $1 (free shipping) eBay relay modules have opto-coupler inputs which can be triggered by, say, only 1 mA of current rather than the 10's of mA to directly drive a relay coil.  This might simplify the interface.

Thanks Stan !!  I'm looking at scenario (b).   Your relay is an excellent choice and would simplify the interface.  I was looking at 12 VDC relay modules on ebay but only found units that required at least 4 ma triggers.  That may be more than the MTH controller can spare.  Your 1 ma choice sounds OK but I couldn't find it.  Do you have a link ?

No link...and I didn't stay at a Holiday Inn Express last night.

However I did pull out two random eBay 12V relay modules from my junk box and both reliably triggered at 0.5 mA.  As you are probably aware, the input trigger to these modules is just a resistor driving the optocoupler LED.  And after the optocoupler, there's a transistor which drives the relay coil.  So very little current is required into the optocoupler LED.  I made my initial comment about 1 mA (or less) based on experience applying these relay modules where I needed to know the trigger current for the purpose of adding time-delay to the relays (e.g., masking intermittent wheel-track dropouts for isolated-rail accessory activation).

Thanks again Stan.  Your relay module looks like a winner.  I'm going to order a few. 

Stan, the relay modules are on the way via the slow boat.  I'll have to get the MTH Traffic Lights out and measure voltage at the controller output.  I can load it with 1 ma and see what happends.  Still don't know where the LED dropping resistors are located, in the controller I presume.  Also I have to determine the controller pin out.

Thanks Stan, you covered what I was going to but I couldn't do an in depth post cuz I was at work. I have the MTH traffic lights on my layout and I I remember correctly there is no difference between the controller for a singly light and the controller for a double light so I have to reason there should be enough current available to drive more than 1ma. As for the voltage, i have no idea what voltage is running the LED's

Sorry posted on wrong one

Ken M

Was searching OGR for info on the MTH traffic controller and stumbled across this:

https://ogrforum.com/t...raffic-light-control

So to keep things simple, does the yellow light do "nothing"?  I'm trying to imagine this and I think the key is your comment that these vehicles stop instantly when track power is removed.  Hence, is the idea to make the relay-controlled section of track just a tad longer than the length of the vehicle...and then to place one each of this section on each side of the light?

As for where the resistors are in the MTH controller design, it seems the worst case is you may need to alter the opto-coupler input resistor on the relay module.  That is, we know an opto-coupler LED operates at about 1V while a Red LED operates at about 2V.  So at worst, you may only have 2V available.  That's a 1V drop and at 1 mA would be a 1k resistor.  I've seen a wide range of values on these relay modules from, say, 1k to 10k.

Looking forward to seeing a video of your intersection in action.  I think it will be quite the crowd-pleaser.