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18 volts, there may be a noticeable reduction in speed and
light level when track power is interrupted.
I’ll be trying the KA2 on my Fn3 locomotives on the brass-
tracked Rocky Mountain Pacific
. I’ll report back later.
Thanks to Jack of Litchfield Station for the Keep-Alive™ mod-
ules for this column.
Hybrid drive
Stan Ames, one of the founders of the NMRA DCC committee,
pioneered a hybrid of track power and batteries to keep the
locos running on his Fn3 layout many years ago.
This technique is most useful in garden railroading where
there is enough room for a pack of AA or so rechargeable bat-
teries and the on/off switch.
You will notice that it looks very much like the capacitor cir-
cuit, except that there is an on/off switch. Since batteries
will hold more energy than even the Keep-Alive™ module,
the switch is needed to prevent unneeded discharge of the
batteries. It can be mounted in the bottom of the loco. Just
throw the switch and run your loco on track DCC power.
When you are done, switch the battery pack off. If you forget
and leave it on, there will be a long charge-up time before
you will have full energy storage the next time.
Stan also has a circuit, using a relay and a transistor to auto-
mate the turn-off. This way, no external switch is needed.
Hybrid drive allows the loco to run on track with a lot more
dropouts than even the KA modules. It also allows you to add
more cells to the battery to match higher track voltages. Since
DCC Impulses Column - 7
MRH-Mar 2013
