User Manual

This document was written by Chris Hansen.
For more information, or to purchase the products shown here, please visit our web site:
www.hansenhobbies.com
Housings:
The electronics industry commonly uses plain symmetrical connectors which have a rectangular
profile. Radio manufacturers like Futaba, JR, and Hitec have opted to make their connectors
somewhat unique by making them polarized; in other words, they only plug in a certain orientation.
This is achieved by beveling the bottom edges (as with JR/Hitec) and/or adding a keyed edge (as
with Futaba). The connectors with the bevels are getting more popular and are commonly
referred to as “universal” servo connectors. Futaba even started adding bevels to it’s
connectors in addition to the key (so that you can just cut the key off and have a universal
connector). Radio manufacturers also developed a protective sleeve for male connectors. These
distinctive features are the reason for the premium charged for servo connectors.
A good solution to lower costs is to just use standard .1”
connectors to make servo connectors. They’re identical aside from the polarization, which can easily be
added. In the image to the left a rectangular housing (we’ve dubbed our “economy servo connector
housing”) is made into a “universal” servo connector by scraping a sharp blade over the bottom edges.
It’s fast and easy to do and the results are extremely high quality. Depending on your other hardware,
this may never even be necessary. Many micro receivers don’t even have cases and therefore don’t
have keyed connector ports. Pretty much all Futaba receivers will accept a rectangular connector
without modification.
Servo Wire
Just like with servo connectors, the RC industry has taken something fairly common and tweaked it for our hobby. Most wire used for servo
leads and extensions is made with high strand-count wire, and a more supple insulation than you would see elsewhere. The finer copper strands
are more flexible and can withstand repeated flexing and vibration
We currently sell two types of servo wire; the first has been dubbed our “economy servo wire” which has a lower strand count and is less
flexible than most servo wire – this is standard UL1007 wire. The second has been dubbed our “deluxe servo wire” and has a very high strand
count (about 2-4 times as many strands as the UL1007 wire) and is very pliable. Both are high quality, and the choice depends on your
application. For any long runs the economy wire would probably be best – it’s cheaper and will be much easier to route through wings (or
whatever your routing through) since it’s stiffer. It also has a tougher insulation which would stand up to abuse better than most softer wires.
If you need super flexibility or have a high-vibration environment (like in a helicopter) then the high strand-count stuff is the way to go. A
higher strand-count wire will stand up to repeated flexing longer.
Servo wire with a silicone insulation is becoming popular now. It is typically sold in 20-22AWG and is probably liked because the silicone
insulation makes it extra flexible (like cooked spaghetti). Another advantage is that silicone will stand up to higher heat before melting. If
you’ve ever shorted out a battery you may have experience the self-destruction that occurs when the high current flow heats up the battery
leads and causes the insulation to melt; even if you fix the short, the leads may have drifted into each other and made a new one and the only
thing to do is yank the leads off as quick as you can (with some pliers), or throw the whole thing outside in the snow. Silicone wire is fairly
pricey, so it may be best reserved for battery leads only.
Twisted vs Ribbon Wire:
Most servo wire is sold in a ribbon form where the three conductors are fused together side by side. Some servo wire is sold in a twisted form
where the three wires are simply twisted in a spiral. If you buy wire with a silicone insulation, it will always be twisted since silicone can’t be
fused together like PVC. I find that ribbon wire is neater and easier to work with. One downside of twisted wire is that the twist consumes
some of the wire length. To make 10ft of twisted wire, you may need 12-15ft of each color of wire. The result is that you have more wire
weighing down your plane and adding to the electrical resistance of the loop. I’ve heard claims that twisted wire filters out noise better than
ribbon wire. This may be true for computer networking wire, where differential transceivers are sending 250MHz signals over a twisted pair
100m long, but I find the claim rather specious for RC systems sending 50Hz PWM signals a few feet.
Wire Size:
Servo wire can range from thick 20AWG (American Wire Gauge) wire to tiny 30AWG wire. Manufacturers typically outfit standard servos with
24-26AWG wire, micro servos with 26-28AWG wire, and nano servos with 28-30AWG wire. Many of the higher power digital servos are being
outfitted with 20-22AWG wire now. The most common question we’re asked is what size wire can be used with .1” connectors. I’ve gone down
to 20AWG, but it really depends on the insulation thickness (too thick and it won’t fit into the housing). On the smaller end (30AWG or smaller)
you may need to perform some trickery to get the crimp done properly.
When deciding what type of wire to use you should consider not just the servo, but the length of the wire as well. The longer the run, the
heavier the wire ought to be to reduce the electrical resistance to the servo. Also remember that the wire size doesn’t tell the whole story –
connectors add resistance as well (see the “Resistance and Voltage Drop” section below). After considering the above, the next thing to think