This is a simple low-power circuit that uses push buttons and relays to control the activation status of a high-voltage circuit.
In the example, the AC power source is configured as a common power socket (in Brazil, power is provided with a 60 Hz frequency and a 127 V amplitude), and the 5 V DC power source can be a standard phone charger connected to the same power plug.
When the upper push button is hit, it puts the circuit in a status that activates both the relays and keeps them powered, even when the button is released. The same principle works with the bottom push button to deactivate the circuit. If both the push buttons are pressed simultaneously, the upper button will have the dominant effect and the circuit will be kept on.
The red LED is used only to indicate if the whole system is powered.
