Model Forum / General / Railroads / December 2006

Mike,
The Atlas switches come equipped with twin-coil solenoid type switch
machines.  These will operate of either AC or DC current.  However, the
nature of these machines is to draw rather large current (perhaps as high as
5 to 10 amperes) while they are actuated.  Because this large current draw
is of  short duration, it does not over heat the transformer in the power
pack nor the plastic housing of the switch machine (but could if the control
button is kept depressed).  The diodes in the power pack that convert the AC
from the internal transformer to the DC for train propulsion are sensitive
to high current, so there is the risk that they could be damaged if you run
your switch machines on DC from the power pack.   Many people like to add on
a simple device called a capacitor discharge power supply to operate twin
coil switch machines.  It uses a small DC current (usually they are supplied
with AC and have a diode in their circuitry to make DC) to slowly charge up
an electrolytic capacitor.  The capacitor can then deliver the large current
needed really snap over the twin coil switch machines.  Geezer