ABC

[rrinker]

 Yes, super simple circuits:

http://home.cogeco.ca/~rpaisley4/DccBodXfmr.html

AND they do not cause any sort of voltage drop in the track, so if you want to have undetected sections between detectors, you don;t need to install the dropping diodes just to keep the track voltage the same everywhere.

These are also available commercially, in products like the NCE BD20, the Team Digital DBD22, or RR-CirKits BOD-8. In case you don't want to try to make your own.

                   --Randy

[southernpacificgs4]

The Twin T was a simple detection system for DC.

Is there something as simple(as the Twin T) for detection of trains in DCC that is simple to built with a minimum of electronic components

[southernpacificgs4]

Hello Jim,

Sorry for the late answer, but ABC is an asymetrical signal that goes to a part of a block, example the stoping section before a block signal.

Due this asymetrical signal on red the decoder go into braking and stops the train.

Lenz is using it in the BM1,2 and 3 and in the BM2 and 3 the advantage that you can use also push/pull trains with the locomotive on the back of the train.

Beside the decoders of Lenz, the ESU decoders and some Zmo decoders are able to detect ABC. I do not know if US decoders, such as NCE and others can detect an asymetrical signal and respond on it.

I understand that you want to run your trains; I do not know how large your layout is and maybe you have one or two guys comming over for an operating session.

But I want to run mostly passenger trains but the main intrest of me is a big central station and locomotive depot where switching is done with passenger trains( making up passenger trains, switching motive power, etc..) but when that is done I would send them out on the main and there they should be running in automatic modus becaus I would focus me on the operations in the Central Station.

My question is if some model railroaders has used this system in the US or Canada and if there are some model railroaders with electronic skills who have built something by themself.

Question for DigitalGriffin:

Why it is beter to use DC in a stop section for trigger the decoder for braking iso asymetrical signal.

You point out that the minus is that if you use metal wheels that there could be a "short" if the metal wheel is across the running section and stop section.

An other question, why still stick with photo cells to detect trains, I think this works with long trains or mabe with multiple photo cells spread over the block but what do you do if a car is cutting himself of the train and stops between the cells or just before or after a cell?

Than the cell is not detecting the car and give a clear signal and he following train will run into that car.

[rrinker]

 The other option supported by most decoders is broadcasting a stop command on address 00, which, besides being the address to run a non-decoder loco on some systems, is also the broadcast address that all decoders are supposed to respond to. DCC BitSwitch and some others have brake zone generators for this.

                              --Randy

 

[DigitalGriffin]

Even though Lenz proposed asymetric DCC to the DCC steering commitee, I don't think it ever took hold.  And the are the sole company using it 8 years later.

There are better ways of doing this today.  For example, there's a flag on most DCC decoders for alternate power source (Analog DC)  If this flag is off, the the time out value set, the train will automatically brake when it hits a DC section.  If an engine passes over a IR sensor or current sensor, then use a DBDT relay to switch from DCC->DC and thereby invoking the auto stop.

This is very very tricky because if a metal wheel gaps the DC to DCC track gap, then you have a short condition.  In this case the best way to handle this is to put a current limiting festoon bulb (Brake light) in series with the DC circuit + leg.

[jrbernier]

  Can you expand on what an ABC braking system is - DCC?

OK - You got me interested.  A little Google search  resulted in some Lenz info on this.  It appears that modules like the BM-1 can be attached to a signal/block, and will send out a specific signal to an engine decoder(in their example they used a Gold Series decoder that listens for this specific 'asymmetric' DCC commands from a BM-1) and this causes the engine to brake to a stop(ABC - Automatic Brake Control).

  Sort of PTC for DCC - I suspect you are going to need special decoders or aux decoders that can read these signals.  Myself, it really makes no sense for most modelers unless you want to set up an unattended operation for display.  I want to 'run' my trains!

Jim

[southernpacificgs4]

Are there US and Canedian model railroaders who are using the ABC braking system?

Did you built it yourself or are you using built up items such like BM1, BM2 or BM3 of Lenz or any other manufacture?