Electronics of Record DoorBell is built on silicon semiconductor components. Power management with DC/DC conversion controlled by micro controller was used in order to minimize heat dissipation and increase efficiency. This means power consumption is much lower comparing to a linear power management and Record Door bell draws less current at higher voltages. Custom sound records are recorded by built-in microphone with pre-amplifier with automatic gain control. The analog signal from microphone is sampled and stored in multilevel memory with long life storage. During reproduction stored signal is filtered by antialiasing filter and amplified by AB class full bridge amplifier. Result of this conversion is then reproduced by built-in laud speaker with diameter 100 mm. Record DoorBell box is made of plywood plates formed into curved case. The back case is attached to front panel by four screws. This construction increases robustness and eliminates unwanted vibrations. During installation and use there is no need to open the back cover. Warning: removing of the back cover will break warranty.
Prototype-construction of the Record Doorbell was published in Czech journal: Practical Electronics (A-Radio) 01/2008, page 15-17. Only Slovak version is available for download.