555 multivibrator circuit diagram

Various forms of self-excited multivibrators can be formed using the 555 time base circuit. The basic circuit is shown in Figure a. When the circuit is just powered on, because C has no time to charge, the ② pin of the 555 circuit is at zero level, causing its output ③ pin to be high level. When the power supply charges C through RA and RB to Vc ≥ Vcc, the output pin ③ changes from a high circuit level to a low level, and the capacitor C is discharged through RB and the discharge switch of the internal circuit. When the discharge reaches Vc≤Vcc, the output terminal changes from low level to high level again. At this time, the capacitor is charged again, and this process can continue over and over again, forming self-excited oscillation. Figure (b) shows the waveform of the voltage on the output terminal and capacitor C.

, this process can be carried out over and over again, forming self-excited oscillation. Figure (b) shows the waveform of the voltage on the output terminal and capacitor C.

555 multivibrator basic circuit related waveforms