AX2500/2850 Motor Controller User’s Manual 75
Cabling to R/C Receiver with Partial Opto-Isolation
The opto isolators must be powered with a 5V supply for their built-in amplifiers to work.
This power is normally supplied from the R/C radio’s battery as detailed in the diagram on
Figure 45.
Note that if full optical isolation is required, it is not possible to connect the third R/C
channel to the radio. Since the 3rd channel is not optoisolated, connecting it to the radio
will cause the radio’s ground to be electrically tied to the controller ground, thus breaking
the optical barrier.
This wiring, with a separate R/C battery, is the preferred method for connecting the R/C
radio.
Cabling to R/C Receiver with Partial Opto-Isolation
This wiring option should be considered only when the Accessory R/C channel (Channel 3)
is required. Since Channel 3 is directly connected to the AX2500/2850’s microcontroller
without opto coupler, it is necessary to connect the radio and controller grounds together
to create a common ground reference for the signal. Since the Channel 3 connector has a
ground wire, this connection will occur when the connector is plugged in the radio. The red
loop wire must be cut to enable that mode. The radio will be powered from its own sepa-
rate battery using this wiring scheme.
By joining the grounds and having the R/C signal connected directly from the radio to the
controller, the full electrical barrier is lost. However, since the radio’s +5V and controller
Controller
Power
R/C Radio Power Opto-
Isolators
Radio
Battery R/C Radio MCU
R/C Channel 1
R/C Channel 2
R/C Radio Ground
Controller
Ground
14
3
7
8
6
5-13
4
FIGURE 45. Fully opto-isolated connection to R/C radio