General Discussion (Model Railroader)

I "think" the Walthers controller unit uses the DC track power inputs to sense direction of travel in order to achieve the proper crossing signal behavior (i.e. turn on when sensor A is covered and turn off after sensor C is uncovered while ignoring sensors B and D; vice versa when traveling in the other direction). With DCC you can't determine direction of travel from the polarity of track power since it is ALWAYS changing!

I'm curious to know how those of you who are running on DCC and are using the Walthers controller (albeit NOT connecting the DCC track power to the controller!) are getting proper signal behavior (assuming my above theory is true). If you're using a spare DC power pack to provide the DC track power inputs to the controller unit PLEASE tell me that you aren't manually flipping the reversing switch on that power pack to match the direction of your DCC train!

 FWIW, Circuitron's grade crossing controller also uses track polarity to sense direction of travel and thus doesn't work with DCC.

Chuck Stancil

Logic Rail Technologies

But it will work with DCC if you use an alternative power source to control the relays and the lights. I use a DALLEE train detection circuit and a Circuitron occilating flasher unit. All i have to do is cut a gap in the rail on one end of the track and then cut another one a few feet further down the rail. (this is the section of track where the road crosses the tracks and you want the crossbucks to protect the automobile traffic within this section of track.

     Next solder a wire from the powered side of the rail. (the rail on the outside of the gaps) thru the DALLEE train detection unit and then solder the other end of the wire  to the rail on the inside of the gaps. What will happen is that the DALLEE TD unit will sense the voltage drop when the train crosses the gap at either end of the rail and will allow the contacts of the relay built into the dallee unit to close.

     Use an old power pack to power the crossbuck signals. The power supply will have one leg go directly to the crossbucks and a leg to the Circuitron osccilation circuit(the common) and the  other wire will go to the DALLEE  relay (NO normally open) and then from the relay will continue to the occilating circuit and then to the other leg of the crossbucks. (There is a wiring diagram that comes with the oscillating circuit so don't dispair.)  One other thing is that the train may be real long so a couple of 1000 ohm resistors might need to go across a couple of  wheelsets on the cars cars and the caboose in the train to keep the circuit alive until the entire train clears the roadway. I have a picture of my circuit here: www.webshots.com/user/bayouman1    go to "trains 2" and the circuit is on page 3

Thanks for all of the information guys. Now, there IS a way to make these things to work on DCC.

I will use this information for a few of my crossings....but....

The question I still have is how to make these lights work off of a switch?

I don't nescessarly want a circuit detection on every crossing since we are going to have operating sessions, and it will make it that more interiesting to control the lights (prototypical or not). Second, I may want to have a huge train go through the crossing gates. As mentioned in an earlier post, you could put resistors on the wheels (etc, etc) to prevent this.... And, I want to have a switch on one particular crossing, since it covers 8 tracks, and I don't feel that interiested in having every single track have a detection circuit (call me lazy, OK??).

And electronic experts know how to make these run off of a switch, or to make the switch act as a control circuit??

Thanks again!

Phil

So, I would need to buy...

x2 Walthers grade crossing siginals
flashing circuit (where do you buy one of these??)
SPDT switch
old power pack

and that's all I need to start?

Phil