A journal following the history, design, construction and operation of Bernard Kempinski's O Scale model railroad depicting the U. S. Military Railroad (USMRR) Aquia-Falmouth line in 1863, and other model railroad projects.
©Bernard Kempinski All text and images, except as noted, on this blog are copyrighted by the author and may not be used without permission.

July 26, 2010

Frog Juicer

Not this kind of juicer!

We are back home after a intense week of traveling around the country to attend family affairs. I was pleasantly surprised to find one of Duncan McCree's Hex Frog Juicers in my mail box. This circuit card provides the logic to power six track elements, usually the frog of a turnout, but it also can be used in a reversing section. The unit senses a short  and reverses polarity very quickly, usually faster than the DCC booster circuit breaker can trip and quick enough that sound units operate without interruption. It will not correct a short due to mechanical failure or external factors, like a metal tool on the tracks. But it will work great for controlling the polarity of the frogs on my layout and on the turn tables. Thus I don't need mechanical switches connected to my turnouts to route power. The only draw back is that the system only works for DCC, so I will need to convert my locos to DCC to make these work. I am looking forward to getting these installed.


  1. Converting tender-motor SMR locos to DCC is not difficult. There is adequate space for a decoder. The key is to use an HO-sized unit rated for at least 2A, such as the NCE. Stall of the motor is about 1.7A. I also recommend adding an extra wiper to one of the tender truck wheels. Newer SMR releases starting with McCALLUM/POCAHONTAS already have the extra wiper.

  2. Dave,
    Thanks for the tip. I'll be working on this in a few weeks.