Image of the TX schematic
For the TX schematic the main power source is 5V coming from USB via
the FTDI232 board.
Image of the RX schematic
For the RX I have included 9V to 5V converter, I have also included a
separate 9V for the L298N motor controller.
Ideally I would use lithium ion batteries,
however I would need many more components and features such as battery
protection and battery charging. Since I didn't have those components
on hand and didn't want to risk directly connecting lithium ion
batteries without protection I opted to use the standard 9V batteries
instead. Simpler and cheaper at the time of making this circuit.
Eventually, I will modify my schematic to include the usage of lithium
ion batteries, especially if I decide to control larger RC cars.