This system is a handheld Tx unit and stationary Rx unit. It's based on
a pair of microcontrollers and a pair of 433MHz radios.The keypad/transmitter is on the left. It consists of a PIC16F628
433MHz transmitter module ( and antenna,
and membrane keypad built into the plastic box. It's powered by
a 9V battery. Power saving firmward allows it to run continuously
for several months...there is no power switch.
The receiver is on the right (above.) It consists of a Parallax 433MHz
receiver module and antenna, PIC16F628 microcontroller, and
Seatalk interface components. Schematic and firmware details are below.
#27980 Transmitter #27981 Receiver
(Photos are from the Parallax web site)
The keypad is covered by label material obtained from OnlineLabels.com. The keypad image was created in Word and printed on a laser printer.