The Astable Multivibrator is another type of cross-coupled transistor switching circuit that has NO stable output states as it changes from one state to the other all the time. The astable circuit consists of two switching transistors, a cross-coupled feedback network, and two time delay capacitors which allows oscillation between the two states with no external trigger signal to produce the change in state. They are free running multivibrators as they require no input for the oscillations. Assume that transistor, BJT0 has just switched "OFF" and its collector voltage is rising towards Vcc, meanwhile transistor BJT1 has just turned "ON". As one BJT goes on and into saturation the other BJT goes off as the collector is connected to the other base. The timing for the switch for each state is given by the R and C.