Have one of those spinning wing decoys with 6 volt motor. Want to reduce the speed of the motor to about half. Is there a potentiometer or resistor available for this? Thanks, Mark

 

Use the site search function to find "PWM" or "Pulse Width Modulation." Plenty of good advice for the reading.

 

You mabe able to use a rheostat, which is the same thing used in old toy trains (the big black box with the knob on top), and in slot-car hand controllers. It mainly depends on how much power the rheostat (pot) will need to dissipate vs. the voltage /current required by the motor -- which is why they tend to be so large.

 

As a cheapo suggestion, eliminate one battery (this assumes the decoy has 4 AA or C cells). Cut a dowel to length, wrap it in foil, and use it to take the place of one battery. This will reduce the voltage and possibly make the motor run slower.

 

Since it's a DC motor you could use and SCR circuit.
http://books.google.com/books?id=Hu...ts=PdpcTyhovs&sig=LG2fU4sxOPRPLp4c72BOT71GbNk

Or something like this.
http://www.elecfree.com/electronic/pwm-dc-motor-speed-control-with-ne556lm311/

Or this http://www.aaroncake.net/circuits/motorcon.asp

You can use a 6v motor if you can provide +6v which is possible with an LM7805 and a diode. or two.
http://www.cpemma.co.uk/pwm.html#nomad