Laptop power supply to boost layout?

Hi Martin,

If I read this correctly, you want to just attach the output of a filtered DC laptop power supply to the track bus at some point on the layout to have more current available at the rails.  That is a no-no on two levels.  One, it will very likely let the magic smoke out of the existing DCC booster on your system since you are back-feeding filtered DC current into the existing booster output that has an alternating current style square wave output.  Second, it just plain won't work.  The way DCC works is the command station (DCC brains) generates a high frequency square sign wave that is broken up into packets that gets sent out to be read by the DCC decoders in the locos.  However, prior to going to the rails, this low power square sign wave is sent to the DCC booster to be amplified and provide the current necessary to run the locos.  DCC is not a superimposed alternating square wave on top of a DC power bus.  The DCC square wave and the power to control the trains are one in the same, (just one wave form on the rails) they are not separate wave forms.

Therefore, if you want to add more current handling capabilities to your layout, then you need to add additional booster(s) along with adding their respective DCC booster power supplies.   A small phone-style cable will daisy chain interconnect between boosters signal line ports to carry the low power DCC signal generated by the command station.  Each booster then amplifies that low power signal and outputs it to the rails to a new isolated, e.g. double-gapped at both ends DCC booster district or “block” which the new booster now powers.  This new booster also provides isolated circuit breaker protection for its “block” so a short circuit, e.g. caused by a derailment, in that “block” will not take down power to other neighboring booster districts on the layout).  A DCC Booster district or “block” could be defined as a full loop of track, a yard area, an industrial switching area, or even just a stretch of track on a long run.

Therefore, the moral of the story is - more power to run more DCC locos means more DCC boosters (and booster power supplies).  But you get more isolated circuit breaker protection as a side benefit.

Scott K.

Austin, TX

Wow, thanks for the detailed answer Scott.  I guess I better not try it.

The MRC booster isn't expensive in the grand scheme of things.  And at least it will allow me to run two separate districts in the future If I decide to go to that.  I just wasn't sure if I needed it.

Thanks

Martin

Sounds like something is wrong if you can only run two locos with 4 amps.  How big is your layout?  Are the locos older ones converted to DCC?  Also, if you are interested, you can use the laptop power supply as a booster if you add one of these Tam Valley booseters http://www.tamvalleydepot.com/...ucts/dccbooster.html

Brendan

Since they are MTH ps3 locos, I think the sounds are causing the higher current draw.

I already found a discounted 8amp MRC booster on ebay and its installed and working good now.

That was an interesting product in the link.  Thanks for sharing.