In all configurations this lost model alarm will sound when a servo signal is lost or when invalid signals are seen. It can be plugged into a spare channel or in parallel with an existing servo via a 'Y' lead.
A different setup is required for failsafe sets. The standard setup will get confused and with a failsafe receiver since the servo signal continues when the link to the transmitter is lost. The solution is to enable the alarm to be activated by a spare channel - by adding the link 'x'. The failsafe has to be set to trigger the alarm. This arangement can also be used for non-failsafe sets so the alarm can be operated from the transmitter while still in range (in addition to loss of signal).
In either configuration the alarm can be set to sound continuously rather than intermittently by adding the link 'y'. See below.
Note: PCB is shown looking at component (SMD)/track side.