[Mano Arrostita] has a video about simulating delay and timer circuits in LTSpice. The video isn’t specifically about the 555, but it does show how the basic circuits inside a timer chip work.

The 555 timer is a versatile integrated circuit (IC) that can control timing in electronic circuits. It's one of the most widely used ICs due to its reliability and flexibility.

In the classic configuration and most variants of the astable 555 multivibrator circuit, the timing characteristics are based on the charging and discharging of a capacitor. However, it can be argued ...

This simple alarm timer circuit is made with 4060 which has an integrated oscillator with a good stability with a relatively wide frequency range. In the circuit diagram the oscillator frequency is ...