Yes this simple transistor circuit can be used as a home door bell and
it’s ON time can be set as preferred by the user, meaning if you wanted
that the sound of the bell to remain switched ON for a particular
period of time, you could easily do it just by adjusting the given pot.
The actual tune is derived from the IC UM66 and the associated
components, while all the included transistors along with the relay are
configured for producing the time delay for keeping the music switched
ON. Link
Parts List
R1, R2, R4, R5 = 1K
VR1 = 100K,
D1, D2 = 1N4007,
C1, C2 = 100uF/25
T1, T3 = BC547,
T1, T3 = BC547,
T2 = BC557
Z1 = 3V/400mW
Transformer = 0-12V/500mA,
S1 = Bell Push
IC = UM66