I am trying to build a circuit that can detect when the motor shaft comes to a halt and want to use this circuit for the same.
The idea that I am toying around is this:
I have a small contactor attached to the shaft of the motor. As the motor rotates this contactor touches two pins A and B there by giving pulse to the comparator through a trigger circuit.
As soon as the connection is established the output of the comparator changes and remains at that state for some time say for 0.25 seconds, before the output can change back, the contactor touches the pins again and again triggers the comparator. This continues as long as the shaft is moving.
But the moment the shaft stops, the comparator no-longer gets any pulse for 0.25 seconds and it changes state, hence i get to know that the motor has stopped rotating.
The reason why I need the trigger circuit is that Even if the shaft comes to halt exactly at the point where it touches pin A and B, the comparator receives only one trigger through the trigger circuit and does not get second trigger for 0.25 seconds.
My expected speed of rotation will be around 1500 rpm. this means that the contactor will touch pins A and B 1500 time in a minute or 25 times a second.
The time between each pulse will be around 40 msec and the duration of the pulse will be for 4 msec only.
Will this circuit work? or is there any better simpler way to do it? How do i select the component values? currently the component values are only for circuit testing, but actual component values for above mentioned time durations have to be worked out...
The idea that I am toying around is this:
I have a small contactor attached to the shaft of the motor. As the motor rotates this contactor touches two pins A and B there by giving pulse to the comparator through a trigger circuit.
As soon as the connection is established the output of the comparator changes and remains at that state for some time say for 0.25 seconds, before the output can change back, the contactor touches the pins again and again triggers the comparator. This continues as long as the shaft is moving.
But the moment the shaft stops, the comparator no-longer gets any pulse for 0.25 seconds and it changes state, hence i get to know that the motor has stopped rotating.
The reason why I need the trigger circuit is that Even if the shaft comes to halt exactly at the point where it touches pin A and B, the comparator receives only one trigger through the trigger circuit and does not get second trigger for 0.25 seconds.
My expected speed of rotation will be around 1500 rpm. this means that the contactor will touch pins A and B 1500 time in a minute or 25 times a second.
The time between each pulse will be around 40 msec and the duration of the pulse will be for 4 msec only.
Will this circuit work? or is there any better simpler way to do it? How do i select the component values? currently the component values are only for circuit testing, but actual component values for above mentioned time durations have to be worked out...
Attachments
-
29 KB Views: 53