stehle@erg.sri.com (02/10/91)
I am looking for an add-on accessory that would be placed on a two-wire telephone line (with a T connection) that would indicate that the ringing voltage has appeared on the line. Ideally, an LED would be set to a flashing mode in response to the ringing voltage. It would stay flashing until the handset was taken off hook; this operation would cause the LED to be extinguished and to cease flashing. Can you direct me to vendors of such equipment? Can you direct me to a schematic to build such a circuit? I am aware of the 20 Dec 90 _EDN_ Idea for Design. Do you have any comments on the suitability of this circuit? Can private telephone systems (e.g., NT SL-1) tolerate lower on-hook DC impedances than the Part 68 specification of 5 megohms? E-mail replies gladly accepted at "stehle@erg.sri.com". Thanks, Roy Stehle SRI International
julian%bongo.UUCP@nosc.mil (Julian Macassey) (02/11/91)
In article <74346@bu.edu.bu.edu> stehle@erg.sri.com writes: X-Telecom-Digest: Volume 11, Issue 103, Message 5 of 12 >I am looking for an add-on accessory that would be placed on a >two-wire telephone line (with a T connection) that would indicate that >the ringing voltage has appeared on the line. Ok, this is simple. You need a gong ringer and a dime. Wire up the gong ringer, but the gong must be open and accessable. Place a dime on the gong. If you find the dime on the floor, the phone has rung. This system was used in Copenhagen Denmark where the phones on Semi Automatic COs had a gong ringer top. Subscribers would place a 5 Oere (Ears) coin on the gong before going out. This was a poor substitute for a Phone Answering machine. But hey, it was cheap if you kept using the same coin. Julian Macassey, n6are julian@bongo.info.com ucla-an!denwa!bongo!julian N6ARE@N6YN (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495