Another type of multivibrator is the astable type. Astable multivibrator devices have no stable states, instead they continually switch between two unstable states. Consequently, they are used as oscillators to provide clock signals for timing purposes. The most basic astable multivibrator, shown in Figure 2-19, consists of two inverters. Note in practice NAND gates are employed. The operation is similar to that of the one shot in its unstable state, but the two capacitive coupling networks prevents either inverter from having a stable state.
 | The 555 timer is an integrated circuit that may be used to implement clocking functions. |
Figure 2-19 Simple astable multivibrator
Copyright © Adrian Als , 1999
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