Good day,
I am currently building a shutter door. I need to create some kind of safety for the door to stop if it gets jammed or if some object is in the way, (for eg. a "stupid" human... I don't want someone to get injured). I was thinking that I should do a current test on the motor and if the load is to high it must stop. the problem is I cant find the
ACS712 Current Sensor in our country 
, is there any other way or suggestions?
Does arduino have a build in function that I can use?
The AC712 is the device you want then just buy it from outside your country, most all suppliers will ship international.
What is your electronics design and build experience ?
he problem is I cant find the
ACS712 Current Sensor in our country
Welcome to the forum.
Have you checked ..Ebay ?
I'm still fairly new in the game, If I had to order it would take weeks (normally 21 days) for the parts to get here. (I'm from south africa)
I'm looking for a quick solution to my problem.
The old garage door actuators I still use simply used an optical chopper disc in the geartrain to determine whether the door is in fact, still moving.
You should be thinking of an intrinsically safe design, not adding a sensor to an intrinsically dangerous design.
This means limiting the current to the motor so it cannot exert dangerous forces and will simply stop on
a blockage. If the motor is incapable of doing damage then any malfunction is also safe.
Its vital the gearing can be back-driven to allow escape.
Whether the forum should advise you on this project, rather depends on who is going to use the shutter door, if its only you then that is your lookout.
However if other people are going to use the door ("stupid" humans ?) and given the obvious safety issues, is it a suitable project for an inexperienced constructor, especially one who needs to ask on public forums for advice on a 'quick solution' ?
MarkT:
Its vital the gearing can be back-driven to allow escape.
I have yet to see a garage door that can be "back-driven".
If obstructed when closing, they automatically reverse.
Think of lift doors - they are very safe noawadays as people have learnt from past mistakes. Lift doors do
not exert huge forces so are intrisically unable to damage.