I want to turn a load like light on for a certain time when one of elevator buttons pressed say button 1 and while the button pressed the load should be on.
In the figure below circuit 1 describe how the controller of the elevator read button .
I tried two circuits to get low signal to trigger 555 timer .
I tried circuit 2 with 10k for R1 and R2 and i faced a problem . *the led of pc817 always on an this tell the controller the button always pressed.
So i tried to change R1 and R2 to 1M the problem disappeared. But another problem happened when the motor of elevator start this trigger the 555 timer :( I am using decoupling caps 0.1u and 10u.
So i tried to add C1 to trigger pin with different values 0.1u ,1u,10u,47u and 100u the problem still exist.
So i went to try the circuit 3. The problem when the elevator motor start run still exist . So i tried to add 1 uf cap to trigger pin the problem disappeared.
Does the last circuit i used practical circuit and will work properly? is there another approach better than what i tried do what i need?