Bistable Multivibrator using 555 Timer

The bi-stable mode has two stable states which are high and low states. The high and low of the output signals are controlled by trigger and reset inputs pins , not by the charging and discharging of capacitors. When a low logic signal is given to the trigger pin , the output of the circuit go into the high state and when a low logic signal is given to the reset pin low the output of the circuit go into low sate.

These types of circuits are ideal for use in automated models such as railway systems and motor push to ON and push to OFF control system.

555 Timers in Mono Stable Mode:

In the mono stable mode the 555 timer can produce one single pulse when the timer receives a signal at trigger input button.  The duration of the pulse depends on the values of the resistor and capacitor. When the trigger pulse is applied to the input through a push button, the capacitor is charged and the timer develops a high pulse and it remains high until capacitor completely discharges. If more time delay is required, higher value of resistor and capacitor are needed.