A digital wristwatch including a transmitter therein for selective activation of a remote electronic circuit by the wearer. The digital wristwatch includes a time-of-day readout encased in a housing supported by a wrist band. Within the watch housing, the following elements are provided: (1) a digital clock circuit for controlling the time-of-day display, (2) a signal transmitter which is operatively, electrically connected to the digital clock circuit, and (3) a battery for operation of both the digital clock circuit and the signal transmitter. The signal transmitter may be activated by one of two methods: (1) a pushbutton switch on the side of the watch housing or (2) by an externally-supplied, electrical signal to terminals on the watch housing. The pushbutton switch extends outwardly from the housing of the watch to enable the wearer to activate the transmitter in a manner which is undetectable to the observer. The terminals, one located under each of the two wristband attachment arms, is used to activate the transmitter from an external device. An example of such an external device would be a pulse rate detector and comparator built into the wristband. The wearer's pulse rate could be monitored and if it exceeded predetermined limits, the signal transmitter would be activated. A receiving station is provided remotely from the wristwatch and is adapted to receive the transmitted signal from the watch to activate an electronic circuit such as a burgler alarm, fire alarm, medical alert, door opener, etc.