Hello gents,

I read Don Vollraths's response to automated operation in this Q&A - http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=001uiy

Like the original poster, I'd like to go DCC but can't think of a way to automate my locos within DCC for unattended operation. I followed the link to Tony's and couldn't find what Don was referring to. :(

To break it down to the simplest explantion, I have two reverse loops running two locos in the same direction with a common length of rail between the loops that relays trigger to auto-reverse. This forces one loco to sit at a station until the other clears the common track. As you guys know, this is very simple to accomplish with DC circuitry, but I can't find any support showing DCC can handle it. Any tips?

James

-- James Uhl (mrsensonic@comcast.net), November 19, 2003

Answers

Apparently the info on Tony's website is gone.

The gist of it is that some (but not all) DCC decoders can be programmed to respond to the detection of DC on the rails and cause the loco to decelerate to a smooth stop if already running with DCC, rather than to keep running. When DCC signals are again detected, it will again follow the DCC loco command and re-accelerate to the set DCC throttle speed.

So the trick is to interlock the switch machines and a relay circuit that changes the DCC track power at the station track to be full-wave rectified DCC (i.e. DC) rather than the AC of DCC. Then interlock the switch turnout controls with occupancy sensors that record the location of the other train and adjust the track switches and the station track voltage relay automatically as the 2nd train passes by. Sounds like photo-sensor circuits could do the job. These can trigger latching relays or electronic Flip-flops that drive signals, tortoise switch machines and track power relays to yield the right sequencing. See Rob Paisley's site for more info on these topics.

Accel and decel rates would be set by decoder CVs. One would have to experiment a little to determine which decoders will or will not work in the described mode.

Contact me direct if you need more help.

DonV

-- Don Vollrath (dvollrath@magnetek.com), November 19, 2003.

See http://www.tonystrains.com/technews/station_stopper.htm

-- Don Vollrath (dvollrath@magnetek.com), November 19, 2003.

Don,

THANK YOU for the prompt and thorough responses. DCC is looking better and better for my set-up every day!

James

-- James Uhl (mrsensonic@comcast.net), November 19, 2003.

The following decoders provide DC-braking: All Digitrax and Lenz products, as well as the newer TCS ones. For the latter check their websits.

Ulrich

-- Ulrich Albrecht (albreuf@auburn.edu), December 10, 2003.