Signals events: the signal is a series of five short beeps. Turn it on or off in the web interface: "Settings" («Настройки») → "Main" («Основные») tab, checkbox "Use buzzer for notifications" («Использовать зуммер для нотификации») (with the checkbox cleared, the buzzer is completely disabled). The same tab has the checkbox "Sound buzzer on program change" («Включать зуммер при смене программы»).
It connects directly to an ESP32 pin (the BUZ1 connector on the printed board): D12 on ESP32 DevKit, GPIO0 on LILYGO T-Relay 4, GPIO39 on ESP32-S3.
Active buzzer DC 3V (red label); 5V (blue label); 12V (black label)
Use an active buzzer. A passive one will not work. Observe polarity when installing. The marking should be on the case, or the long leg is plus.
If you have a buzzer and want to find out whether it is active or not: Set the power supply to 3 volts, connect the minus, and touch the other contact with the plus a few times. If there is no sound, raise the voltage to 5 volts.
If you hear a tone, a beep, it is active; if you hear only clicks when the plus touches, it is passive. The same goes for 12 volts.
A 3 volt buzzer is recommended, but a 5 volt one has been used too. The volume is quite decent.
There is no volume control for the buzzer. You can try adding a resistor in the power line, or simply cover the hole slightly with tape.
