DCC idea for "power independence"

David Nebenzahl · 2006-12-19T22:17:51+00:00

Reading a thread here about the problems of powering locos across dead sections of track gives me an idea. I may not be the first person to have come up with this, so let me know if you've heard this before. It also may be impractical for several reasons, discussed below, but I still think it's an interesting idea.How about building a DCC decoder that uses battery backup for both itself and any powered functions (motor, lights, etc.)? Actually, rather than modifying the decoder itself, this could probably be designed as a power-handling "front end" to the decoder. Here's how I envision it working: it would use a small 12-volt rechargeable battery, which would power it and the loco. The power module would take care of keeping the battery charged from the track voltage, when available, and would draw power preferentially from the tracks, when available.But when track voltage disappeared, the battery would be used as the power source. So instead of being able just to go over short sections of "dead" track, this could potentially power a loco over good-sized sections of track without power.*Problems*1. The battery and power module would have to go somewhere. I'm seeing a rechargeable battery about the size of a 9-volt battery. This would work fairly well in a steam loco, where the battery and the power module could go in the tender. But in an N-scale diesel, forget it.2. What happens when you shut your layout down at the end of a session? The power module, seeing track power go to zero, would kick in and possibly drain the battery. Not a show-stopper necessarily, but not a good feature. Either it would have to be shut off manually with a switch on the loco, or possibly through the decoder, by sending it a special "shutdown" command. Or there could be a timeout timer that would shut the whole thing down after a short interval.So whaddya think? Should I pitch this idea to Digitrax?

C

Craig Zeni 19 years ago

Lenz is already doing it, albeit with capacitors not batteries:

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:)

CZ Wet Blanket, NC

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Peter W. 19 years ago

Right - and my comment also had a smiley. :-D

Peteski

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Stan Ames 19 years ago

I don't follow rec.models.railroad much lately. To busy converting my roster to batery backup :)

To help others understanad this and avoid the "absolute horseshit" comments I put up a WWW page (including videos) explaining the concept as I have implemented it.

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Since I wrote this set of pages Lenz built a small circuit board to replace the relay and charging circuit. This also reduces the cells needed to 6 or 8 and allows much more range in the DCC track voltage for the charging circuit to work. I have my first couple installations just now going though testing of the revised ciircuit.

As has been pointed out earlier in this thread, Lenz uses capasitance pickup so the decoder does not need an electrical pickup to the rails to read the DCC signal.

For those of you that have problems with this consider the properties of a capasitor. Two pieces of metal seperated by an insulator. Now what is a metall wheel on dirty metal track....

The DCC signal is bi-polar which has the effect of charging and discharging this rail, wheel, dirt capasitor. Software within the decoder signal processes this charging/discharging cycle to reconstruct the DCC signal.

Please note that this rail/wheel capasitor is not the energy store. Energy storage to power the decoder and motor, while no electrical pickup is present, is provided by a seperate on board capasitor or battery,

One surprise is that it can work off of one rail, not sure how it gets the ground reference but it does wook as illustraded in the video.

Now back to the conversions as I have 25 more locomotives to go.

Stan

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DCC idea for "power independence"

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