It allows you to remotely control up to two different electrically controlled units and to remotely read the condition of as many devices or the presence of tension on power lines.
We describe the simple remote control, obtained by adding to the regular circuit, two optocouplers and both relays, together with the basic components. The circuit we propose has two main …

In order to understand the different functions, let’s now take a look at the schematic diagram of the unit.

2 IN and 2 OUT Schematic Diagram
The entire control is handled by a Microchip PIC18F46K20-I/PT microcontroller, programmed with a firmware that controls the GSM/GPRS module’s activity, reads the logic condition of the two opto-isolated inputs and sends commands to the two relays in the …

Now that we have seen the electric scheme, we can work on the practical aspect of the project; let us state in advance that its making presupposes a double-faced printed board with metallic holes, using many SMD components, all this in order to reduce the overall size of the device.

Now you have to get to know the commands needed to manage it and use them at their best.  Relevant commands must be given by SMS, on the understanding that a message can contain multiple messages properly separated; some commands, due to their importance, they require a password which is 12345, set by default during the first activation of the …