Dave Hub said:
What is the point in having insulated frogs if we all have to convert them to live.
Hi Dave,
having an insulated frog is the simplest way of making a point that doesn't require any further switching of polarity at the place where the two rails meet (the frog). With an insulated frog the two routes out of the point remain electrically independant. It's a common design that's been around as long as 2-rail electric trains. Some brands of point are made so that both routes remain powered (eg LGB points), others are made so that only the route that for which the point is set is powered (switched by the contact of the point blades against the rail)
Now, this is all fine until you find yourself running short wheelbase locos at slow speed: wheels and/or skates obviously loose electrical contact as they run over the insulated part of the frog, so the pickups available to your short loco are reduced and can lead to juddering or stalling. The wider the radius of point you use, the worse this can become as the length of the insulated part of the frog must be longer due to the shallower angle of divergance.
The way round this problem is to use live frog points where the frog is metal, as sold by some manufacturers. However, this adds complexity in that you must keep the actual frog section isolated from the rails beyond the point (especially if there are any power feeds beyond the point) and must then use some form of polarity switch to connect the frog to whichever route is selected.
... does this make it always live on both rails or just the route in which the point is set?
Only the route which is set is live beyond the point. Both rails of the other route become connected to the same polarity unless you isolate the rails beyond the frog as mentioned above. If the trackwork beyond is just a siding then this is not a problem unless you use DCC and want a loco parked in the siding to remain powered up.
So, you don't HAVE to do this conversion but you can either do something like my conversion or buy live-frog points if you wish to maximise slow running ability. Other ways to help are to run locos with flywheels to get them glide over frogs or other electrical interruptions, or with DCC locos you can use a Power Buffer which supplies power to the decoder during the interruption.
I come from a background in smaller scales (N gauge) where it's accepted that live frogs give better running, therefore I'm used to the additional complexities of frog switching etc. and don't give it a second thought.