Using 555 to make an electronic timer hypnotist

IC1, R2, RP1, C1, etc. form a monostable circuit, and SB1 is a timing start button. When SB1 is pressed, IC1 is set, and pin 3 is high, and timing starts. The timing time T=1.1(R2+RP1)C1. According to the parameters in the figure, the timing time is roughly 20 minutes to 40 minutes. The high level of pin 3 powers IC2, and IC2 starts working. R3, RP2, C3, etc. form an astable multivibrator. The oscillation frequency of the parameters in the figure is roughly between 0.4Hz and 14Hz, which can be adjusted by RP2. The oscillation frequency is output to the speaker through pin 3 of IC2, making a sound similar to raindrops, which makes people fall asleep. When the timing time of IC1 is up, its pin 3 outputs a low level, IC2 loses power, stops working, and automatically stops.

If a longer timing is required, it can be achieved by replacing RP1 with a larger resistance.