Powered Frogs in DCC

[Mark5]

Been doing some more dangerous reading on DCC ...

Are powered frogs a danger or do the systems detect possible shorts?

[cv_acr]

If you run through a switch backwards that has a powered frog, you'll create a small short - but that'll happen regardless of whether you're using DCC or analog DC.

The DCC system will detect any shorts and shut down to protect itself from any overload. (It'll keep checking for the short, so once you correct the problem it automatically comes back.) Using circuit protectors is a good idea on larger layouts to break the layout down into sections so that a problem such as above at one end of the layout doesn't affect other areas. (If you have multiple boosters, with each powering an isolated section, then a short will only affect the single booster)

Speaking from experience, there's little that's more annoying than running a train on a large club layout and suddenly everything stops because of something that's happening at the far end of the layout that you can't see, accompanied by calls of "OK, who's shorting the layout?" (Some old sloppy wiring essentially turned the entire layout into a single big block. That's since been fixed, and part of the layout divided into two new districts and a new booster added. We've also been adding circuit breakers to individual blocks/sections to further eliminate accidental shorts from affecting larger areas.)

[flight2000]

Is there a comprehensive book out there that covers wiring a layout for DCC?  I want to do it right the first time, but have no experience with electricity other than to shut it off before screwing around with a ceiling fan.....

Same for wiring up a layout with block signals and linking your layout to a computer.

Thinks in advance,
Brian

[mmyers]

Try this link:
http://www.wiringfordcc.com/

[flight2000]

Try this link:
http://www.wiringfordcc.com/

That's a good website, but I can't take the desktop to the layout (yet...).  I get lost trying to figure out the DCC friendly portion of the turnout wiring.  To bad they don't have a DCC for Dummies out yet, because that's about where I'm at right now.  About the only thing I'm proficient at so far is programming the engines with the cab numbers.  Took me about a week to figure out I could program different lighting arrangements. 

Thanks,
Brian

[ednadolski]

If you run through a switch backwards that has a powered frog, you'll create a small short - but that'll happen regardless of whether you're using DCC or analog DC.

That should not happen if the frog is properly isolated (forward/backward should make no difference either).

If the frog is electrically connected to the point/closure rails, then you can get a short if/when a metal wheel bridges the gap between a point/closure rail and an adjacent stock rail having the opposite 'polarity'.

In "unfriendly" turnouts, the frogs are not always electrically isolated from the closure rails, and the point rails also may be electrically connected thru a metal throwbar or pivot bar.  If a turnout is "power routing" that usually means it is not DCC friendly.

If a turnout is labeled "DCC friendly", then it has the proper frog isolation, and the point/closure rails are wired to remain at the same polarity as the adjacent stock rails, regardless of which route the points are thrown.

The Atlas Code 55 turnouts are DCC friendly.  The old Micro Engineering turnouts were power-routing, but the newer ones have been reworked to be DCC friendly.

[cv_acr]

If you run through a switch backwards that has a powered frog, you'll create a small short - but that'll happen regardless of whether you're using DCC or analog DC.

That should not happen if the frog is properly isolated (forward/backward should make no difference either).

If the frog is electrically connected to the point/closure rails, then you can get a short if/when a metal wheel bridges the gap between a point/closure rail and an adjacent stock rail having the opposite 'polarity'.

That's pretty much exactly what I said... 

If the frog is isolated and NOT powered, then you can run through the switch in any direction and only worry about derailing things if it's the wrong direction.

If the frog is powered (to avoid the small potential dead spot) based on the position of the switch, then running through the switch the wrong way will cause a short because the frog is the wrong polarity.

On our club layout, all the switches have isolated (non-powered) frogs, with feeders attached to the point rails to keep them the same polarity as the stock rails. Since any decent engine should have electrical pickup on both trucks, as long as the point rails are properly fed you shouldn't have any stalling due to dead spots. (Unless you've got a little tiny 4-wheel critter that has a wheelbase only as long as a frog)

The only other danger is if you have an engine that just manages to sit with each truck on a different frog at a certain place - then it will lose power.

[John]

[wm3798]

I believe the Tortoise/Hare combination switch machine/decoder has a sensor that will automatically throw the switch if you approach from the frog end an cause a short.  Another $40 investment to protect us from ourselves! ;D

Lee