PowerSupply. - Here is Circuit Schematic Power Supply for Line Follower Robot using LM7805. Usually LFR is powered by a battery supply voltage of 9 to 12V while most of the circuitry requires only 5V.
|Figure 1. Circuit Schematic Power Supply for Line Follower Robot using LM7805|
You can use 6 to 8 AA cells (or a 9V 6F22 battery-not good for long run) as the power bank of the LFR. The fixed-voltage regulator LM7805 (U4) is used in the power supply circuit to convert the higher input supply (Vcc) voltage to a lower value (+5V) to make the MCU happy. LM7805 works even without the buffer capacitors but it is better if capacitors are used as they will stamp down the voltage fluctuations. Adding one 10nF ceramic capacitor across each dc motor terminal ( +/_ ) is another good practice to suppress unwanted noise generated by the motor.