Multi-vibrator circuit composed of 555

Crystal oscillator

Quartz Oscillator 3225 20M OSC

The following is a circuit diagram of [Multi-vibrator circuit composed of 555 ]

Working principle: The circuit has no steady state, only two temporary steady states, and no external trigger signal is needed. The power supply VCC is used to charge the capacitor C through R1 and R2, so that the uC gradually rises, and when it rises to 2VCC/3, the uO jumps. To the low level, the discharge terminal D is turned on. At this time, the capacitor C discharges through the resistors R2 and D, causing the uC to fall. When it drops to VCC/3, uO jumps to a high level, the D terminal is turned off, and the power supply VCC is again Capacitor C is charged through R1 and R2. In this cycle, the oscillation is continued, and the capacitor C is charged and discharged between VCC/3 and 2VCC/3, and a continuous rectangular pulse is outputted, and its waveform is as shown in (b).