Nuts and Volts - November 2010

■ FIGURE 1.

Figure 2. It also wakes up every 2. 3 seconds and looks for a valid transmit signal and code for 20 microseconds. If there is none, it goes back to sleep. It counts four 2. 3 cycles and then flashes either green or red indicating the door positions. If it receives a signal from the transmitter, it changes its display and will flash the LEDs until the transmitter stops its transmission.

Both micros control the transceiver’s power using the PDN line control. The T/R SEL pin differentiates between sent data and received data.

Construction

Boxes Go to the downloads link indicated here and download Garage. There are templates included in the attached files. Print and cut them out. With the two halves together, turn the box over and locate the battery holder area. Place the battery area towards you and turn the box face up. The board and antenna go on the far end as shown in Figure 3. (The box will not go together if the top half is reversed). Using a glue stick, glue the antenna template, front panel template, and side templates to the box. Using a drill press, drill the proper size holes as indicated on the templates. The receiver box is done the same way, however, there are no side holes; only the front panel and antenna. After the holes are drilled, use hot water to remove the templates and glue.

Transmitter On the top of the board, mount the Linx module first, then the microprocessor, capacitor, terminals, and the voltage detector. The tilt switch is mounted on its side with its terminals toward the edge of the board. The transducer is mounted on the bottom of the board. Look at Figure 4. Note the polarities on the components which require them. Thread the wires from the battery holder through the slots of the battery compartment, through the antenna, and place it through its hole. Add the board over the antenna and secure with a screw. Use two self-tapping screws to secure the board to the box.

■ FIGURE 2.

Receiver On the top of the board, mount the Linx module first, then the microprocessor, capacitor, resistor, and the voltage detector. Add the transducer, LEDs, and the switch on the bottom side. The best way to insure the correct length of the LEDs is to place them in the board, place the board in the box, seat them in their holes, and solder the leads. Take a look at Figure 5. As above, solder the battery holder wires and install the antenna.