My question is generic in nature about electronics system design. I am trying to put together an RC car which is powered by an AVR Atmega168 chip. It communicates through an HC-12 module and has a quadruple h-bridge chip to move the tires. The schematics is as follows:
The issue is that, without any load, the voltage regulator LM7805 will provide a stable 4.99v output on standalone basis. However, when put in the configuration below with micro-controller sending and receiving data, the voltage drops to 4.72v or so, depending upon how much current is drawn by the components. I am not an electronics engineer but I suppose any system which is powered by batteries must face similar issues and there must be general solution for such issues. In the schematics above, motor is being powered through 2 separate lipo batteries of 3.7v each. The voltage drop is therefore entirely by the 3 ICs.