Use one of the control flow pins (RTS or DTR) of a TTL232 USB interface to drive a relay as described on https://blog.pasqualefiorillo.it/drive-a-relay-with-an-usb-to-uart-interface/
Drive a relay with an USB-to-UART interface
Use one of the control flow pins (RTS or DTR) of a TTL232 USB interface to drive a relay as described on https://blog.pasqualefiorillo.it/drive-a-relay-with-an-usb-to-uart-interface/
Drive a relay with an USB-to-UART interface