DCC Turnout Wiring Tips
To Avoid Short Circuits

The December 2009 issue of Model Railroader magazine has a good review of DCC turnout wiring and techniques to avoid short circuits. There was one point missing from the article that can simplify frog wiring.

In the past I've used micro switches to power frogs either directly or via relays that are driven by the micro switches or auxiliary contacts on switch machines. I had a number of twin coil machines and some tortoise machines on my previous layout. The new Utopia Northern has only one twin-coil machine and the rest are Tortoises, Tam Valley servos or ground throws.

However, the micro switches have been my only option for my manual throws. I would mount them under the layout when possible but sometimes I had no choice but to top mount them. That creates a problem to disguise them.

If you have read my pages about hand-laid turnouts, you'll know that I have been using Fast Tracks templates and jigs. The method involves isolating the frog by cutting the rails on both sides to create a "dead frog". 

Usually most locomotives will bridge the dead section without faltering.  However, there is now a simple way to wire the frog with one wire. That's right.

Fast Tracks is now selling something called a Hex Frog Juicer for automatic frog polarity control. You hook two wires to the control bus for that power block and then one wire to as many as six frogs. (The electronic board can also be used for reversing sections as i am doing on the new UNRR but that's another story).

Without getting too complicated, the idea is that the electronics react to a short circuit so quickly that the DCC system doesn't even know there's a short circuit. The electronics switch the polarity before the DCC circuit breakers trip. 

I had installed my first Hex Frog Juicer in the yard at Utopia that has been partially rebult to improve operations. The Hex Frog Juicer worked perfectly. It certainly was quicker to install than micro switches. I added more on the East Utopia module that is a main component in the new UNRR.

You'll find it useful to go to the Fast Tracks website and have a look at the paper templates. They show where to make the cuts in the rails and the printed circuit board ties if you're using them. By the way, I experienced a new short circuit problem that had me baffled for a week until I found it. I had installed a twin coil switch machine on one of the new turnouts made with printed circuit board ties and throw bar. The metal rod connecting the throw bar to the switch machine was causing the short through the metal of the switch machine. The connecting rod was outside one rail, not between the rails. I had to cut the foil on the throw bar between the connecting rod and the the rail to stop the short.

Tip: One tip in the magazine article that's worth remembering is to paint nail polish on the frog to stop wheels from shorting. This is a short-term solution because the nail polish will wear off over time. You're better off to wire the frog or leave it dead if your engines are not stalling.


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