I am brand new to model railroading and am working on my first layout. Up until now I feel I have been doing fairly well but hit a snag yesterday while trying to wire and place dwarf signals. The lamps in the signals are 1.5v 30mA and I have the proper drop voltage resistor for a 12 V system. The problem I have is the digitrax dsc51 is only outputting .5 volt from Trk A and trk B. Everything else on the layout works fine (two trains and 6 tortoise machines plus two DigiTrax switch machine controllers). After checking with digitrax on specs it appears that the unit is fine and operating as designed. Once I learned to measure voltage from trkA/B to ground it produced the spec'd voltage. My question is do I need to wire lights using the common from the ground on the controller and refigure my drop resistor value or do I need a separate power supply? I was told the 51 would be all I would need for a 8x4 layout Ho scale.
Thanks to all who provide feedback and info is greatly appreciated.
Ed Jones
You really can't wire such things directly to the track power - how are you controlling them? If you are trying to switch the signals using the contacts ont he Tortoises, you will want to have a seperate power supply for that. This dicument from Circuitron shows how to wire them: http://www.circuitron.com/index_files/AN/an-6000-02.pdf
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Do I understand that you are running track power to your dwarf signals? If so, I have to ask why? What are they signaling?
Dave
Lackawanna Route of the Phoebe Snow
Ed:
There is a bit of a different mindset required for DCC versus DC. DC powerpacks usually have an separate output for wiring lights etc while a DCC system does not. A good source of information that you might want to look at is Alan Gartner's site : http://www.wiringfordcc.com/index.htm.This is a start and there are more sites that are crammed with useful info but please don't be afraid to ask here. Have fun.
Joe
You cannot power a Tortoise with DCC track power, either. They require DC. DCC is frequency modulated square wave AC. Buy a 12 volt DC wall wart at Radio Shack for your switch motors.
He said he has Digitrax switch decoders, must be DS64's or DS44's for Tortoises. So they are indirectly powered by the track power. Unless auxiluary power is applied tot he DS64.
Ok, Randy.. Thank you. I picked up a 12v wall wart and have the DS64 and 4 switches running off it now. Just need to set up a bus for the turnout signals get those wired and I should be set. Thank you all for the info and links, after a little rewiring I should be back on track.
I didn't notice the part about the DS64s. Yes, they can be powered by the track, mine were for a year or so, but they work more reliably on their own power. The DS64 can power LEDs in series with the switch motor if you are using slow motion stall motor switch machines, but I don't know how you could wire a dwarf signal that way. If you are using the aux contacts on the Tortoise you will need a source of power.
You probably can;t wire a premade signal like that - they usually have a common for the two LEDs thus only 3 wires, so you can;t easily put them in series witht he tortoise motor like you cna bi-color 2 lead LEDs. The app note shows how to hook up signals to one of the contact sets with an external power supply.