provide a negative going pulse to trigger the monitor timer ic2 the monitor timer ic2 is triggered by receiving a coded pulse from the remote unit 50 and re triggered via the transistor q1 each time a new matching encoded signal is received if a matching code is not received after a preset time interval for example ten seconds the monitor timer ic2 low triggers the flip flop in ic1 the flip flop ic1 enables a piezoelectric audible alarm 86 the audible alarm continues to sound until the unit is deactivated or a properly encoded rf signal is detected the portion of the electrical circuitry of remote unit 50 that actuates the alarm is shown in fig6 the portion of the circuit board shown in fig6 includes a monitor timer ic2 transmitter enable pulser ic1 pin 9 and buzzer flip flop ic1 pin 5 an enable switch 88 is electrically coupled to the rf transmitter a pulse decoder 90 is electrically coupled to the rf receiver not shown which detects the digitally encoded signal from the master unit 12 each time a matching code is received and decoded a pulse is transmitted to ic1 pin 13 the monitor timer input ic2 is connected to the decoder via a capacitor 92 the capacitor 92 differentiates the pulse decoder 90 to provide a negative going pulse to trigger the monitor timer ic2 and the transmitter pulser ic1 pin 8 the monitor timer ic2 is triggered by receiving a matching coded pulse from the master unit 12 and is re triggered via the transistor q1 each time a new matching encoded signal is.