Eagle Tree Pro, Glide, Flight and Boat Seagull Wireless Telemetry and Data Recorder User Manual

Page 7

Page 7

We are often asked whether existing magnets on spark ignition engines can be used. The answer is “yes” in most cases, if
you can install the sensor near enough to rotating magnets. We have found that these engines typically have 3 magnets,
with 2 magnets mounted with one polarity, and the other one with another polarity. The easiest way to use these
magnets is to install the sensor with the printed side facing the magnets (as described below) then run the motor and see
what RPMs are recorded after setting up the gear ratio. If the RPM looks like it is only half of the correct value, double
the gear ratio value you entered, to compensate for only one magnet being in the right polarity. We have received
problem reports of RPM reading errors when the RPM sensor is mounted very near the magneto of spark engines, so we
recommend mounting it 180 degrees away from the magneto, or as far away as possible.

Installing the RPM Sensor

Once the magnets are glued and completely dry, temporarily position the RPM sensor so that the side of the sensor with
printing (or colored dot) is facing the side of the magnets WITHOUT the red line. The sensor now needs to be glued
so that it is held rigidly into position. Before gluing, put a small spacer (1-2 mm thick) between the sensor and one of the
magnets to ensure proper spacing.

If desired, a small piece of brass tubing can be glued or heatshrunk to the back of the sensor to ease mounting and increase
stability.

After the sensor is glued and completely dry, remove the small spacer and rotate the propeller to ensure complete freedom
of movement. Also make sure that the sensor won’t vibrate and come in contact with the magnets during driving. If this
happens, the sensor will be destroyed, and the Recorder could be damaged.

Once these steps are complete, plug the Futaba style connector on the sensor into the recorder as shown in figure 1.
Note that a standard Futaba style servo extension cable can be used to lengthen the wire if needed.

Using Existing RPM Sensors

Several of our customers have been able to use existing RPM sensors, such as governors or turbine sensors, with our
products. The following steps must be followed:

Determine the “pinout” of the existing sensor. Compatible sensors will have Power, Ground, and Signal
connections. The Recorder’s RPM pinout, from left to right, is: Power (black wire), Ground (red wire), Signal
(white wire).

Devise a “Y” cable to connect your existing sensor to it’s connection, and also to the Recorder’s RPM connection.
NOTE: Power for the sensor should come only from the connection the sensor is normally plugged into. So,
only Gound and Signal wires should be routed from the existing sensor to the recorder. The power wire of the Y
cable between the sensor and the recorder should be cut before connecting it to the recorder. This is necessary to
avoid connecting the power of the existing sensor connection to the Recorder’s power connection.

Thoroughly test the system to make sure the sensor still works with whatever it was originally connected to, after
Y’ing to the recorder.

Installing Secondary RPM Sensor(s)

With the PRO recorder, up to 3 MODIFIED secondary RPM sensors can be used, for a total of 4 RPMs. The secondary
RPM sensors plug into the 3 servo slots nearest the switch on the Recorder. The servo slot nearest the switch is RPM
sensor 2 in the software. Each secondary RPM sensor used MUST be modified as described below. With non-Pro
recorders, up one secondary RPM sensor can be used for a total of 2 RPMs.

The secondary RPM sensor(s) must be modified by swapping the red and black wires in the RPM sensor plug. Carefully
pry back the plastic tabs that hold each pin in the plug, remove the red and black pins, and re-install them so that the pin
order is RED, BLACK, WHITE. The second RPM sensor plugs into the servo port with the red wire to the right, nearest
the edge of the recorder.