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radio controlled model boats, R/C, scale, BaD, Dumas, Crockett, Monterey, Warship, ship, model, 1/96, wood, balsa, plank, strip, craftsmanship

All about Speed Controllers
by Roger Harper
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Page 2 of 5

Mechanical Speed Control

Back in the early 80's this type of speed control made it's presence in the RC car world.  It provided a simple mechanical speed control, while others of this type only offered a simple "On Off" type of control.  The controls where made to be activated by servo.  The first type mounted on top of the servo.   As the servo rotated, it activated micro switches.  These switches where connected to ceramic resistor to reduce the voltage going to the motor.  They often only offered on or off.  Some had two speeds, half and full.  These did not give much control.

The second type of mechanical speed controls added reverse.  These controls where often mounted away from the servo and were activated with a push rod connected to the servo arm.  These controls also used ceramic resistor to reduce the amount of voltage going to the motor.  These controls were often called "Step" controls.  Because they often offered three forward speeds, they stepped from one speed to the next.

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(Click on image to enlarge)

Both of these types of mechanical speed controls offer a high ampere handling capacity.  They were often connected to 6 or 7 cell NiCad packs and to 540 type motors. Mechanical speed controls are very inefficient and sometimes dangerous.They run the risk of catching fire..

Without a doubt, there is no need to use these types of controls in anything less than a race boat.  These serve no use in a slow scale tug or warship. 

Wire Wound - Resistor Types

This type of speed control offers a major improvement over the mechanical speed control.  This type of control offers Proportional Control.  This means that as you increase the lever on the speed control, the motor increases speed.  They may, or may not offer reverse.

These controls are made with a wire wound resistor.  These units do not like have loads or motors that draw large amperes.   Stay away from using 540 type motors Or motors with high amp draws with this type of speed control!

The most common of this type of control is made by Dumas.  They make one to handle 6 volts and one for 12 volt systems.

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The Dumas speed controls offer both forward and reverse smooth proportional control for your model.  They both have a built-in fuse to protect the control from over load.

I have seen a few web sites slam this control.   I have NEVER had any problems with this type of control.  They are designed to be used with the Dumas Pittman motor.  When you use these controls with other motors is when you get into trouble.  They do not tolerate high ampere motors.  They also require a bit of maintenance to keep them in good working order.  The only thing I have found to be bad with these controls is the cost.  They are priced a bit high, compared to the Electronic Speed Controls on the market today.   If you have one though, they will provide you many years of service.

You  can  send a tip here, or send Email to:rktman56@yahoo.com

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