The objective of optical isolation is to remove any electrical connection between the motor circuit and the receiver circuit in the radio control system. Motors tend to cause severe electrical spikes when they operate and these spikes can be fed back into the receiver through the power connections. This electrical noise can degrade the receiver performance in a non-isolated system. In an optically isolated speed control such as the SCO, there are two sections, a control section and a power section, coupled together by an optical interface. The optical connection uses light emitting diodes to turn electrical signals from the control section into beams of light. Photo-transistors convert the beams of light back to electrical signals in the power section. Below is the block diagram for the entire system.
The motor and receiver must have their own separate batteries. Do not connect the receiver battery ground and motor battery ground together. There is no need for a power switch on the motor battery. When the receiver power is turned off, the power section will automatically shut down, drawing only 12 microamps from the battery. It is safe to trickle charge the motor battery while the SCO is connected and is in the shut down mode.
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