Matches 51 - 91 out of 91 < 1 2
Match Document Document Title
3872440 HOSPITAL COMMUNICATION SYSTEM  
Signals are transmitted in a hospital communication system between sub-units of room units and a central nurses station over a common high frequency line, each room unit having an identifying high...
3864527 INTERCOMMUNICATION SYSTEM USING CONTROLLED GATES  
A three port controlled gate and an intercommunication system incorporating the gate are disclosed. The gate is so formed that the control signals for opening the gate can be applied to the same...
3836718 INTERCOMMUNICATION SYSTEM WITH A TIME LIMITED ADVANCE NOTICE SIGNAL  
An intercommunicating system provided with at least one generator which produces an advance notice signal controlled by a capacitor for supplying a time-limit bias to the generator whenever an...
3826875 AUTOMATIC SECURITY COMMUNICATIONS SYSTEM  
An automatic communication system adapted to provide security communications within an apartment building is provided to include a plurality of time delay circuits to automatically discontinue the...
3708629 INTERCOMMUNICATION SYSTEM FOR APARTMENT, OFFICE BUILDING AND THE LIKE  
A two-way intercommunication system for selectively interconnecting a central station, such as an apartment or office lobby, with any one of a multiplicity of remote units, such as individual...
3567868 INTERPHONE DEVICE HAVING PRESENCE INDICATOR MEANS  
An interphone designed for mutual conversation-type interphone systems and having a plurality of high impedance lamps the turning-on of which indicates the presence of personnel by the...
3527890 INTRAPLANT VOICE COMMUNICATION SYSTEM  
3400226 Hand telephone set  
3379837 Central energy simplex intercommunication system capable of paging and conference calls  
3376506 Combined paging and intercommunication system with separate paging reply line common to all stations  
3297824 Remote station intercommunication system  
3291911 Two-way intercommunication system  
3156774 Communication system for drive-in restaurants and other applications  
3147555 Electronic apparatus for classroom instruction  
3097265 Simplified communication system  
3091667 Intercommunication system  
3071647 Intercommunication system  
3045065 Intercommunication system  
3043912 Intercom for automobiles  
2973586 Device for instructing the public in the proper use of dial-equipped telephone station apparatus  
2951123 Voice activated intercommunication system  
2935565 Sonic signalling and ranging apparatus for marine use  
2913524 Loudspeaking interoffice telephone  
2912502 Waystation employing transistor amplifier  
2896021 Inter-communication system  
2883456 Circuit arrangement for intercommunication systems  
2868879 Plug-in portable telephone system  
2855461 School to home communication system  
2841647 Privacy insuring means for intercommunication systems  
2820098 Signaling system  
2820096 Circuit arrangement for loudspeaker telephone systems  
2819340 Voice operated intercommunication system  
2815399 Tray or support therefor  
2815398 Intercommunication systems  
2814672 Inter-communication system  
2793248 Portable intercommunication telephone  
2790027 Telephonic unit with battery-powered auxiliaries  
2783308 Intercommunication apparatus  
RE08248 Title is not available  
0934811 Title is not available  
RE12103 Title is not available  
Matches 51 - 91 out of 91 < 1 2