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Q.
What servo should I use for my, car, boat, plane, helicopter……?
A. One of the most frequently asked questions is "What servo
should I use for…..". While there have been many magazine articles
that attempted to provide a general rule of thumb to answer these questions,
we offer you the following information.
- There are two factors
that go into the design of a servo, Speed and Torque. In many cases,
Hitec will create one servo geared for speed while sacrificing some
torque, then create its twin, which is geared for torque at the sacrifice
of speed. Our 525/545, 625/645, 925/945 servo products are perfect examples.
- If you are not
sure which servos to use go with high torque.
- When in doubt ask
your peers about servo application questions. Look at what others are
using in comparable applications. Usually the kit manufacturer will
suggest a servo of a certain physical size and torque value specification
in the aircraft, car or boat plans, it's wise to follow their guidelines.
- Even though micro
servos like the HS-81 may offer 38oz/in of torque, they are not appropriate
for larger powered aircraft due to the flight loads placed on the control
surfaces. Smaller servos have thinner gears that are inherently more
fragile than those of "standard" sized servos.
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Q.
What is the difference between an analog and digital servo?
A. The difference is in how the servo motor is controlled via the
circuit board (amplifier). The motor of an analog servo receives a signal
from the amplifier 30 times a second or at 30Hz. This signal allows the
amplifier to update the motor position. Digital servos use a high frequency
amplifier that updates the servo motor position 300 times a second or
at 300Hz. By updating the motor position more often, the digital servo
can deliver full torque from the beginning of movement and increases the
holding power of the servo. The quick refresh also allows the digital
servo to have a tighter deadband.
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Q.
My older Hitec servo has a white connector, can I use it?
A. What you have is a older servo with a Molex connector. Hitec cannot
support this product anymore because that type of Molex connector is not
manufactured anymore. You can change the plug to a modern Hitec "S"
connector using part #57342S
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Q.
What is the difference between coreless and cored servos?
A. In a standard motor like the one in the HS605 servos, there is
an iron core between two permanent magnets. Around this core is the wire
winding. The core generally has either 3 or 5 sections. As the core moves,
these sections cause the core to hesitate slightly when it reaches a different
magnetic polarity. This is called ratcheting. Because of this ratcheting,
the cored servos have less start up torque and a wider dead band.
In a coreless servo,
there is no iron core. There is one permanent magnet around which is a
bell of wire. When electricity is supplied the bell spins around this
magnet. Since there are no sections or core, there is no hesitation between
poles. This gives the coreless servo better start-up torque and resolution.
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Q.
My quarter scale servo came with a y-harness. How do I use it?
A. The y-harness is included so you can defeat the Battery Eliminator
Circuit of AM receivers. This is required, because that circuit limits
the amount of current the servo can draw causing it to behave erratically
or lessen its torque. To use the y-harness, plug it into the same channel
that you plan on using for your servo. Then plug the switch and battery
into one end and the servo into the other end. Do not use a different
battery to power the receiver. Because the negative and positive traces
in the receiver are linked to each channel, the battery on the y-harness
will power the remaining servos and the receiver.
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Q.
Can I use loctite with my Karbonite gears?
A. It has
come to the attention of the Hitec Product Service Department that some
customers owning Hitec's KARBONITE gear servos are using thread locking
compounds on the servo horn screws. Thread locking compounds such as the
popular Locktite™ brand, are for use with METAL to METAL fasteners.
USING A THREAD
LOCKING COMPOUND ON KARBONITE GEAR SERVOS WILL CAUSE THE PLASTIC TO FAIL.
Thread locking compound
instructions typically warn against their use on plastics, as most plastic
material will become brittle and shatter. If you or any of your friends
have used thread locking compounds on plastic / KARBONITE geared servos,
please cease using them immediately and contact a Hitec dealer for a replacement
gear set.
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