Powered by 220 volts.
The sound resembles the sound of the call electronic phone.
The tone can be adjusted by selection of capacitor 0.05 UF.
The device is equipped with a sound projector DAMS with a coil resistance of 50 Ohms. The quality and type of sound projector very strong influence on the colour of the sound and functionality of the system as a whole. The capacitors should be at a voltage below 300 volts.