Читать книгу System Reliability Theory - Marvin Rausand - Страница 135

A simple doorbell system is shown in Figure 3.4. The pushbutton activates a switch that closes a circuit from a battery to a solenoid that activates a clapper, which again makes sound by hammering on a bell. When your finger is lifted from the pushbutton, the switch should open, cut the circuit, and thereby stop the doorbell sound. The following failure modes may be defined:

Figure 3.4 Doorbell and associated circuitry.

1 No sound when the pushbutton is activated (by a finger.)

2 Doorbell sound does not stop when finger is lifted from pushbutton.

3 Doorbell sounds without activating the pushbutton.

A similar doorbell system is analyzed in NASA (2002).