Coding system for an alarm system and the like

A system for registering and transmitting a preselected code to a receiving station comprising switch means operable between open and closed states;

• an oscillator responsive to the operation of said switch means to said closed state for producing a plurality of pulses;
• an advance signal generator for generating an advance signal when said switch means is operated to the open state;
• control means having a plurality of states and being moved from state to state in response to said advance signals;
• bi-directional counting means connected to said oscillator for counting and registering said pulses in a first direction in response to a one state of said control means and in the opposite direction in response to another state of said control means;
• said counting means generating a signal at an output terminal when the count therein is zero;
• display means for displaying the count registered in said counting means;
• transmitting means responsive to said other state of said control means for connecting said oscillator to a transmission line;
• and lead means connecting said counting means output terminal to said advance signal generator for generating an advance signal to terminate the operation of said transmitting means when a signal is present at said output terminal.