NOISE SUPPRESSION FOR MOTORS

Please always remember to install noise suppression on any and all electrical motors in your model boat.  While most of us usually remember to do this on the main drive motor(s), we usually forget the other motors commonly found in our models.  Some examples of these often forgotten motors are:  Bow/Stern Thruster, Radar, Anchor Winch, Deck Winch/Capstan, Cranes and Ventilation Fans.  You may be asking yourself why this is so important; after all, these are small motors.  Yes, that is true but more often than not these small motors generate as much electrical noise (if not more), than the larger drive motors.  Anyway, large or small, motors should be suppressed.  When you get right down to it, this is not a complex task and only requires basic soldering skills and a little bit of patience. 

The ideal set up consists of three (3) capacitors.  One capacitor should be connected across the motor terminals.  Each of the remaining two (2) capacitors should be connected so that one lead is on a motor terminal and the other lead is connected to the motor case.  This will provide the most practical suppression method.  If after adding these three (3) capacitors, the motor still causes radio interference; it is time to replace the motor with a better quality unit.  Earlier I mentioned that a lead from two (2) of the capacitors needed to be attached to the motor case.  This can cause some problems as the cases of many of the motors we use don’t take solder well.

Even after taking a file to the case to generate a nice clean bare spot, solder may not stick.  I have seen many motors ruined when too much heat was applied in an attempt to get the solder to flow.  To make these capacitors work only requires an electrical connection to the motor case.   It does not have to be soldered.  The best way around the problem is to mechanically clamp the capacitor leads to the case.  Most motors have threaded mounting holes in the front or back endplate.  In this case, simply thread the proper screw into one of these holes and wrap the capacitor lead around the screw.  Tighten the screw down and the lead will be trapped between the screw head and motor face.  Presto, you have your electrical connection.  For those of you that have done any house wiring, this is the same idea.  If your motor does not have a threaded mounting hole (or you can’t use it for some reason), then a hose clamp around the outside of the motor can be used to hold the leads firmly in contact with the case.  In this situation, it is wise to sand, file or scrape through any protective coating and make sure that you are contacting the metal of the motor case. 

The capacitors that you want to use for this are ceramic disk capacitors rated for at least 35 V.  These can be purchased at Radio Shack.  For the capacitor across the motor leads, use a .01 uF and for the other two (2) capacitors, use .047 uF (Micro Farad).

Give this a try!  You will be amazed at the increased radio range and smoother control that will result.