Hello guys!
Please help!
I need to make precise gate opener with timer (like the one in supermarkets) but with precise laser light.
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I need to buy linear actuator or linear servo (not to strong, some cheap one, up to 30$), and I don't have photoresistor with relay(s) with a timer, I need advice about it. (maybe I don't have to use photoresistor with relay timer, maybe just to use Arduino? )
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I have:
Demand:
Laser light always on - laser is covered by an OBJECT - photoresitor detects object and activate linear actuator (or servo) - linear actuator extends ; hold on when reach the end for 3 s ; retract at starting position.
I need advice for material and for code..
Thank you, thank you, thank you. 
Consider using limit switch when the motor extends to desired position, so Arduino will know when to stop and you won't need to hard code the variables.
omersiar:
Consider using limit switch when the motor extends to desired position, so Arduino will know when to stop and you won't need to hard code the variables.
It's OK to use limit switch here, I can include it.
I would start the 3sec delay to retract actuator after the laser sensor is active again and limit switch is read.
Ray_Beebe:
I would start the 3sec delay to retract actuator after the laser sensor is active again and limit switch is read.
No, in this specific case must be as mentioned.
So, it's:
laser sensor change detected (object is coming and cuting the laser line) => actuator (or linear servo) is activated => in limit position switch is activated - 3 s hold => retract actuator.
Thanks!
I have three GTO Mighty Mule (commercial) gate openers on my property. They are actuated from a remote control transmitter, but could also be actuated by a switch or by a magnetic sensor located in the path of the vehicle approaching the gate.
The sequence of operation that I use is:
- press button on transmitter
- gate opens and stays open for 1 minute or what other time is desired (programmable)
- gate closes automatically
One nice feature is that if the gate is opening and you press the transmitter button, the gate stops and stays open until you press the button again.
These gates are pretty powerful and can operate a 16' 100 pound gate with no problem. Internally they have a large worm gear connected to a 12v DC motor. There are limit switches to control how far the gate opens and closes. The limit switch that controls the closing of the gate is mechanically adjustable so that the amount of gate "swing" is easily adjustable.
The gates also have a safety feature that you might want to consider and that is if the gate encounters an object while opening or closing, it automatically reverses direction.
I'm not sure what your particular project will be used for, just offering a few suggestions on how the commercial gates operate.
Charles
@oldvetteguy Thanks, interesting idea, but it all needs to work with laser and photoresistor...
it all needs to work with laser and photoresistor
Simply replace the gate opener switch with the laser/photoresistor circuit.