In some cases, sequential systems act on solenoids that beat on metal tubes with varying lengths.
The basic circuit of an electronic doorbell in blocks is shown in Figure 1.
When triggered by the doorbell button, the circuit runs a program that produces a sequence of notes programmed in the chip. The signal corresponds to the notes and is amplified by a common low-power audio amplifier.
Audio amplifiers with output powers in the range between 1 and 5 watts are common in commercial circuits.
The way this kind of circuit is installed is not much different from any common doorbell. The trigger button (pushbutton) is placed near the door.
Many types allow more than one trigger point. The circuit is powered from the AC power line with a transformer to supply DC power. The power supply providing the low voltage to the DC circuit needs to remain on all the time.
Some types of doorbells and chimes are coordinated with intercoms and video cameras.
