This Relay Module 2-Channel is compatible with Arduino, it uses two optocouplers to grant galvanic insulation, and it can drive a load up to 7A 250VAC per channel.
The DS1307 serial real-time clock (RTC) is a lowpower, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of battery-backed NV SRAM. Address and data are transferred serially through an I2C, bidirectional bus.
This small circuit can recharge in an extremely simple way Li-Po and Li-Ion cells (3,7V). Charging current selectable between 100mA and 500mA. Powered via USB connector.