Automatic Shutters

Principle of operation: The Arduino counts the holes on the roller shutter using an infrared receiver; the infrared emitter diode is positioned on the other side of the roller shutter. When a hole is sensed, the Arduino increments or decrements a counter to determine the position of the roller shutter. To connect the actuators and the sensor to the Arduino I used two LAN cables (see last step).

• To draw the schematic I used the Dia program. It is very simple to learn, available for Linux and Windows, and it is freeware. You can download it here. The NE555 is configured as an astable multivibrator which generates a square wave at 38kHz to drive the infrared emitter. The infrared receiver is a TSOP1138 with an internal filter for 38 kHz, and the demodulated output signal can be directly connected to a microprocessor. For the safety of the Arduino I connected its outputs to two optoisolators (but this is not required).
• Finally, I made two actuators using two old 14v relays and a few other components such as two 2N1711 transistors, two diodes and a 12v power supply.
• Here is the schematic: https://docs.google.com/open?id=0B8tHAfj...

Here is the Arduino code: https://docs.google.com/document/d/1-nug...

Other photos of this project.