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.
(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.
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.
|
