isolation

[sleeper33]

ok guys and gals here goes

I need a difinitive answer if there is such a thing for this question.

Q: when wiring for dcc is it manditory to isolate the frogs on switches(points) been told diffent things and am getting confused.

any assistance welcome

 

[selector]

There is no simple answer.  The problem is that if the frog is powered, it is more involved to make sure your wheels don't inadvertently get the wrong power coming to them from the frog and cause a short, particularly with decoders.  There is always a risk that decoders could fry.  So, it was decided that the simplest thing to do was to make frogs unpowered (cut off, or isolated) from everything else.  That makes 'em dead, but you won't get shorts at them.  Now, though, you may have problems with small engines getting across that dead zone.

So, it depends.  Are your power-requiring devices going to be able to straddle a dead frog handily and still make it across?  That's the bottom line.  If you are running long steamers and diesels with multiple pickups, dead frogs are dead simple.  They're all I use.

For those who know they have to have live frogs, then the frogs must be switched positively back and forth commensurate with the route they line at the time.  Some turnouts are power-routing all the way along them, and my understanding is that many DC and DCC users swear by them.  If wheels are in gauge, and nothing touches another polarity, then powered frogs are fine.  Note that some guys use DPDT switches to flip the frogs back and forth, while some switch machines have a DPDT capability built in for just this purpose...and they do it automatically as you desire the points to line one route or the other.

I hope you get others piping up with their own impressions and experience.

[jrbernier]

  The actual frog itself really is not the problem.  The points/closure rails tends to cause more problems with a short caused by a derailment.  With DC, the 'short' is limited to the engine that caused the problem.  With DCC, that 'short' can shut down the entire railroad.  I have seen a lot of layouts with live frogs and DCC - They work just fine.  What the owners do is set up 'power districts' around the layout.  That way, only the 'district' is affected and the 'short' does not shut down the entire layout.

  If you have 'DCC friendly' turnouts like the new Walthers-Shinohara or Atlas - Use them.  If you have a big supply of the older turnouts, go ahead and use them.  Remember, good trackwork no matter which type of turnout you use is the key to good operation.  And there will always be someone who 'runs a switch' - that is just human nature.

  My friend has a very large layout(entire basement) with a mix of old and new Walthers-Shinohara turnouts.  The only issue was with small wheelbase engines stalling on the long insulated frogs of #8 turnouts.  He uses Caboose Industries ground throws and replaced them with the Caboose Industries ground throw with the electrical contacts to power the frogs.

  My layout has Atlas Custom Line turnouts and I have not powered the frogs.  My diesels/steam have no problem running over the #6 turnouts.

Jim Bernier

[rrinker]

 Exactly as Jim says. The frog generally is not a problem. if it IS powered, it should be done so reliably via switch machine contacts, or some means that does not rely on the point/stock rail contact. Personally I did not power my #6 Atlas turnouts, but all ,my diesles had at least 8 wheel pickup and had no issues even creeping over the frogs. Smaller locos, or those with only 4 wheel pickup might have problems.

 A more likely palce of shorting occurs in those turnouts that power both point rails to the same polarity as the stock rail against which they press - thus on the 'open' side there is a narrow clearance between a stock rail and a point rail that has the opposite polarity. 

 The whole "DCC Friendly" thing is blown all out of proportion to the amount of trouble it actually causes. If your wheels are all in gauge (test with an NMRA Standards Gauge) you probably will never have a problem no matter how the turnout is wired.

                                --Randy

 

[sleeper33]

Thanks alot guys.

Thats really cleared it up for me . was going down the powerdistricts route but was worried that I would have to do alot of electrical work that I was not comfortable with.

 Thanks once again