MiniHub with accessories

Optional RPM sensors (Tachometers)
Thank you for purchasing
the N2 Industries
MiniHub+
Direct Coupling (Gasoline Engines)
NOTE ON RCXEL Kill Switches
Specs
Input:
There are several options for RPM sensors that will work
with this unit; brushless motor sensors, optical sensors and
direct coupling (with gasoline engines that provide Tach
outputs).
N2's Brushless Motor Sensor
FrSky Smart Port
ID: 21 ( aka 20 in 0 based counting)
Voltage: 5 - 12v (2 Lipo Compatible)
Supporting Sensors: (not included)
1 RMP (Tachometer)
2 x Temperature Sensors
3 x Voltage Sensors( 0 - 5v )
1 Current Sensor
Instructions
Function of the MiniHub+
The MiniHub+ is designed to take in and process inputs
from multiple sources. When it is initialized it checks those
inputs and marks the ones that are active. Then, in a roundrobin method it reads, processes and sends the data out.
Reset Button
There is a reset button that will force the MiniHub to reinitialize. This is helpful when switching out sensors and
testing. If a sensor is changed out then use the reset.
LED’s
There are three LED’s on the MiniHub+:
1. A red one that is under the location of “Current” and
will be on any time that there is power.
2. A red one under the SPort that will go out when
communications with the SPort has been established.
If the SPort LED turns on again it is a signal that the
SPort might be overloaded or other problems.
3. The green one is status, While initialization; slow
flashing is testing the analog inputs for validity, mid
speed flashing as the MiniHub+ tests for what
sensors have been attached, fast flashing while
waiting to establish SPort communications and then
solid green when connection with SPort is complete.
Positioning and securing the MiniHub
There is no right or wrong place for the MiniHub+, but
placing it in a central location makes it easier to work with
when plugging in sensors.
Make certain that the reset button in not pressed against
something as that will create random resets.
Velcro, servo tape and double sided foam are all good
ways to secure it.
The RCXEL Kill Switch switches ground on/off
instead of power (+V) so you will have to
disconnect the ground; thus I do not suggest
using them and I cannot guarantee that the noise
will be acceptable. See the “Tips” page.
N2's Optical (IR) Sensor
FrSky Optical Sensor (discontinued)
Optional Current sensors
There are three current sensors available and one of them
can be selected and placed in the “Current” header position.
5A current sensor. Great for monitoring the receiver/servo
combination for any over current situation (stalled servo,
etc).
20A current sensor. Great for monitoring current of
motors in Park Flyers with 1 or 2 cell Lipo batteries.
30A current sensor. Great for monitoring the mid-size
electric aircraft using 2 or 3 cell LiPo’s.
Optional Temperature sensors:
There are several choices for temperature sensors. The
sensors are keyed so that it will work appropriately, just
keep polarity. The sensors have Futaba style servo plugs
and the keyed side must be on the outsides.
Wire loop sensor - T11 and T21
The wire loop sensor is exactly the same type of sensor
you have seen before with a servo lead instead of a micro
plug. The sensor is capable of high temp sensing with the
silicone tubing. It can be used in any place where it can
be attached and have a good thermal conductivity. It can
be used in Nitro or Gasoline where you can get the sensor
fixed into fins of the engine.
Potted stud type sensors- T11 and T21
The potted stud temperature sensors (small, medium
and large) are for nitro or gasoline engines. The smaller
one can be used to attach a stud to an engine and the
others (medium and large) can be used under a spark
plug to monitor head temperature. These sensors are
potted in a high temp epoxy.
Strip sensor - max 257° F (125° C.) - T12 and T22
The strip sensor is perfect for monitoring the
temperature of Lipo batteries and some ESC's. Attach
with double sided tape on a nice flat surface (do NOT use
foam type double sided tape!) or just use regular heave
tape to hold it against the surface.
Probe type sensor - max 257° F (125° C.) - T12 and T22
The probe type sensor is for those places where it can
be slid into tight spaces and the friction fit will hold it in
place. Many ESC's use heat shrink, and that heat shrink
can stretch, letting you slip a probe type sensor against
the heat sink of the ESC, just be careful to not let the heat
shrink split or tear.
Motor sensor - max 221° F (105° C) - T12 and T22
The motor sensor has been designed to be mounted
inside of a brushless motor to give you an accurate
temperature of the motor's temperature.
NOTE: Disassembly of the motor is required!
Optional Voltage sensor:
The MiniHub+ has 3 voltage headers for monitoring
voltages. The voltage sensor pins are for sensing a voltage
from 0 - ~5.0 volts. Do not exceed 5 volts.
One cell LiPo’s can be used directly..
The use of a voltage divider ( such as the FrSky Battery
Voltage Sensor - FBVS-01) is required if you wish to monitor
higher voltages.
The FrSky FBVS-01 requires knowledge of soldering and
the standard voltages of LiPo batteries
NOTE: OpenTX versions
When using OpenTX versions 2.0.xx the V4 (aka A4) will not
work properly because it will collide.
As of this printing OpenTX version 2.1 has not been
released. The instructions may need updated when it is
released, Check
http://n2-industries.com/minihub.html
for any new directions.
Warrantee
N2 Industries, LLC warranties that the product will be free from
defects in materials and workmanship for a period of 1 (one)
year from the date of purchase.
Warnings
Intended Uses:
The Mini-Hub+ and associated sensors
are intended to be used exclusively for recreational
purposes in radio controlled models. Other uses are
not supported. Further, using the MiniHub+ or
sensor’s in situations where it’s use or failure could
result in loss of life, bodily injury or property damage
is expressly prohibited.
Radio Interference:
It is extremely unlikely that the
installation of the MiniHub+ will affect your model’s
radio range or control. But, as always, after making
electronics change to your model it is very important
that you range and function test your model once it is
installed to ensure that there is no impact on your
system.
TIPS
Gasoline Engine - Direct Connect (Electronic
Ignitions) and Kill Switches
To connect to the typical "Tachometer" lead from the
ignition module you will need a male/male extension and
move the jumper from the outside most position of the RMP
header to the inner side (move it over one pin). This will
prevent both the MiniHub and the electronic ignition trying to
power each other.
NOTE: Some kill switches will not work unless you
remove the ground (black). RCXEL is one of them so I do
not suggest using then
But if you want to try them then make a 2” wide strip of
aluminum foil about 2-3’ long and wrap the wires for the
Tach/RPM from the MiniHub+ to the kill switch and around
it. I can’t guarantee that it will work but some have had
success with that approach.
Telemetry Setup
If using Tach/RPM Sensor
Scroll down in the Telemetry page until you find "Blades: X"
and set the number of blades for your application. Directly
coupled gasoline engines will be "1".
Scroll down until you find where you want to display the
RPM data and then select it. Scroll down to "RPM" and press
enter.
If using Temperature Sensors
Scroll down in the Telemetry page until you find where you
want to display the temperature data and then select it.
Scroll down to either "T1" or "T2" and press enter.
If you are using two temperature sensors then repeat the
process and select the other temp data.
If using Voltage sensors
Scroll down in the Telemetry page until you find A2 (or A3
or A4) and adjust the "Range", "Offset", "Low Alarm" and
"Critical Alarm". You MUST have a "Range" selected ( not
"0.0") to be able to place a voltage sensor in the "Screen"
page.
Scroll down to "Screens" and select where you want to
display A2 and then select it.
If you are using more voltage sensors then repeat the
process and select the other voltage sensor data.
Setting the "Offset" setting.
The MiniHub has a base voltage reading of 0 - 5v for V2, V3
and V4. After version 2.0.10 of OpenTX you will need to put
in an offset for V3 and V4. The correct offset on a 5v range is
1.13 of offset. For 10v the offset will be 2.26, 20v - 4.54v
offset, etc.
Brushless Motor RPM Sensor Tips
Getting your "number of poles".
Most manufacturers of brushless motor sensors will not
provide the complete information for you to set up the
"Blades" number in the telemetry page.
The number will be the number of magnetic poles for1/2
of a revolution. ( 14 magnets, use "Blades - 7").
Many times you would have to disassemble the motor bell
and count the number of magnets in the outside of bell
housing. This might void your warrantee so a link to a site
that will help you define your motor manufacturer by
manufacturer and model of motor is:
http://www.ecalc.ch/motorcalc.php?ecalc&lang=en
eCalc is not totally free. It will give you a random set of
data and you might, or might not, see your motor in the
tables. The cost to get the full set of data is 98 cents (for a
month’s of time). I suggest that the cost is very reasonable to
get the correct data for your motor without having to
disassemble it. Plus it is a very helpful tool for
motor/prop/battery balancing.
Anomalies/erratic reading/false readings
The N2 Industries Brushless Motor Sensor is shielded and
should not give false readings. If you choose a different
brushless rpm sensor and you are getting readings that do not
make sense then try wrapping the sensor over some
aluminum foil to shield it.
Optical RPM Sensor Tips
Visible Light Optical Sensors (old style FrSky sensor)
These sensors are looking to see 'black' as the prop is in
front of the sensor and a light sky looking out otherwise. It
needs light. If you have a gray/wooden prop then consider
painting the back side of the prop with some flat black
paint. That will help the sensor to see black/white
transitions better.
Infrared Optical Sensors
These sensors are using an infra-red LED to illuminate the
prop. They are looking to see a 'bright' space while looking
at the prop and, in an otherwise, pitch black sky. Using
reflective tape on the prop will improve readings.
If you are having problems getting steady readings from
one of these sensors then there are a few things that you
can do:
1. Move the sensor closer. But that is not always easy.
2. Align the sensor to be facing the flat of the propeller.
This means angling the sensor to match the pitch of the
blade where you are trying to read the sensor. The will
decrease the amount of 'light' that is bouncing away
from the prop. You want a 90° angle against the prop.
3. Add some reflecting tape to the blades of the prop.
You will find that type of tape at your local auto parts
store. I found a 3ft x 2" roll at Napa (thin and not too
heavy). Also available at Walmart sold as “Duck Tape”
brand of reflective tape in auto motive section.
Using the FrSky FBVS-01
Setting the "Range" setting.
The important thing to understand the FBVS-01 is that it is
just a “divider"; it divides the voltage by a fraction (1/2, 1/4,
or 1/6).
The MiniHub+ is based on 5v so if you are using the FBVS
with the 1S setting you need to set the "Ratio"(or “Range “)
to 10v (2*5v).
If you are using the FBVS with the 3S setting then you
need to set the "Ratio"(or “Range”) to 30 (6 * 5v).
The S1 setting will work on a 2s Lipo (range 0-10v; a 2cell
Lipo is 8.8v max);
The S2 setting will work on a 2 cell Lipo OR a 3 cell Lipo (
Ratio/Range 0-20v; a 2 cell Lipo is 8.8 max, 3 cell Lipo is 13.2
max).
The 3S setting will work for up to 30 volts so it will work
for a 4 cell Lipo’s or 5 cell Lipo’s but will not work on a 6 cell
Lipo.
If you have access to a multi-meter you might want to
compare the actual battery voltage with the telemetry and
adjust the "Range" up or down a point or two so that your
setup will be the 'dialed in' .
Setting the "Offset" setting.
In OpenTx version 2.0.xx you will need to put in an offset
for V3 and V4.
The correct offset on a 5v range is 1.13 of offset. For 10v
the offset will be 2.26, 20v - .4.54, etc.
Note: You do not need the FBVS if you are monitoring a
single 1s Lipo (4.4v max voltage).