Block Signaling/Power System

You can do this conventionally with relays, However in command,if you cut off power to the block the train does not resume it's last command state when power is restored. I have made circuits for people who have stalled DCS engines in command on a block by reducing power to 8 volts rather than shutting it off. Then when power is resumed it resumes operation. I dont think this can be done with TMCC however.You could send a code signal to stop if you had it but you would have to have engine ID also as to which engine is on that block you want to stop. This gets involved and there are some solutions such as supermarket type scanners on the bottom of a loco for example. It could also be programmed with a logic controller as to what engine is on what block. I run only conventional and my layout is totally automated.

You may want to contact the person in this thread,Ted Hikel who made up some software..

 https://ogrforum.com/t...onventional-controls

Dale H

Another general concept for block control is to disconnect power to just the motor in the engine.  So rather than disconnecting track power to the block, a localized signal (optical, magnetic, electrical, whatever) is created in the block where the engine is to stop.  A detector in the engine senses this localized signal and removes power to the motor until the signal goes away.  Track power is still applied to the engine electronics which keeps sound, smoke, lights, etc. running which can be useful.  This would also work with conventional operation.

Obviously this requires opening up each engine to be used with the system.  The sensor/cutoff electronics could be inserted in-line with the 2 wires going to the DC motor which should make installation fairly simple.  I figure less than $5 in parts in each engine and less than 1 sq. inch of circuitry - no computers or programming required.  I'd be surprised if someone hasn't already implemented something like this and hopefully they will share.

An interesting idea Stan. Problem is it adds to an already complex system and there is not a lot of room in a lot of locos.. Many are so crammed full of junk might be hard to get something else in there. The sound system would continue to run as if the loco were moving. Too bad it memory was not incorporated into the system when it was designed,it would have been easy to do. Most electronic gadgets work this way or can be made that way. A TV for example, if you are watching channel 6 and you pull the plug,when you put the plug back in channel 6 resumes.

Dale H

One issue with engines with cruise control would be they'd go to max throttle when the motor was disconnected.  So, when it was reconnected, they'd leap out like the old Odyssey lurch starting up again.  Maybe adding a TDR would help with the jump...

Indeed.  Some guys are reluctant to fiddle with the internals of their engines (for good reason).  This would be a Your Mileage May Vary situation depending on engine type.  I'd think some diesels might have wiggle room.  And if no space in a steamer's engine perhaps it could reside in the tender if motor wires go over a tether.

Good point about the sound.  However, in some steamers it appears the chuffing sounds are mechanically sync'd to the spinning motor or drive wheel.  So if the motor drive electronics is putting full voltage to the motor, if the drive wheel does not spin then the chuffing sounds stop.  Likewise in some diesels, it appears the prime mover sound reverts to the first notch if it does not detect the motor spinning.  So again it's a YMMV proposition.

Keen observation GRJ.  The most direct implementation of a motor cut-off would be a relay.  But to your point, when the relay switches the motor back on, it would jerk, lurch, whatever.  What I was thinking was the motor cut-off switch would be implemented with a transistor.  This was primarily because of size since a power transistor is many times smaller than a relay.  But more importantly a transistor can be configured to "slowly" turn on rather than a relay's on or off choice.  So a relatively simple circuit could ramp up the current to the motor over, say, several seconds when power is re-applied to the motor.

As with Dale's comments, this would be a YMMV proposition since no doubt there is a motor drive board out there which gives up, shuts down, whatever, if no motion is detected when applying full-power to the motor.

I think the Legacy units with the diagnostics might be upset if the motor stops turning, but I've never tested that theory.

Thanks for all the clever ideas! I think I have the TMCC spec and am a software developer but not really a hardware guy. I would think there might be a way to build a little memory module that works sort of like a flight data recorder but just keep the last command received stored.

Then, it'd have enough of a capacitor to withstand the short power outage while the block clears and on power resume it would send the signal it has in memory. I think it'd be nice to have an on off switch too incase people don't want this. Seems like a nice little feature that wouldn't be expensive or difficult to implement, I just don't know what the demand would be.

It's not the end of the world here if I have to grab back control of the engine as this is mainly to prevent collisions from not paying attention.

Any thoughts on if I have to use a relay or if there is a transistor with the specs for this level of electricity?

Truthfully, I'd use a relay.  Total isolation, and you can get a pretty small one that will handle the current.  One issue with the motor is that you can't count on a ground reference, as it changes depending on direction.

Maybe put a super capacitor on the power supply to the board. Not familiar with the Lionel boards but if it is a 5 volt system with a 7805 regulator,they make 5.5 volt 1 farad capacitors. You could try one on the regulated side. I think it also senses track voltage somehow to determine whether it is in command or conventional. You may have to deal with this. I would be interested in your results. To cut track power I use relays,easy to use. Using relays for block detection is shown here.

http://jcstudiosinc.com/BlogShowThread?id=410

Dale H