Did You Know...
...that Charles Goodyear performed some of his experiments on rubber while in debtor's prison? He was there so often he referred to it as his "hotel". Chronically in debt because of poor business sense and ill health, Goodyear depended on the generosity of friends and family. Even after he unlocked the secret to vulcanizing rubber, he was unable to improve his financial situation. When he died, his estate was $200,000 in debt.
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| Number | Title | Issue Date |
| 5764755 | Ring-signal generation in a SLIC A ring generator circuit is included in a subscriber line interface circuit (SLIC) for providing a high voltage ring signal to a plurality of ringers at the same time. The ring generator circuit includes an adder and divider circuit connected to receive a... | 06/09/1998 |
| 5402480 | Call signal generating circuit A call signal generating circuit includes a step-up transformer having a primary winding and secondary windings and a first switching circuit coupled between the primary winding of the step-up transformer and a D.C. power source for turning ON/OFF at a fr... | 03/28/1995 |
| 5402484 | Telephone circuit assembly A circuit assembly which includes an interface circuit between a subscriber line and exchange devices of the kind with two amplifiers connected in a bridge configuration between the battery terminals and having a means of detecting the output currents; a ... | 03/28/1995 |
| 5293420 | Ring trip circuit A first part for picking up a signal being proportional to a ringing tone signal transferred on a subscriber line; a second part for extracting an ac component from the thus picked-up signal; and a third part for receiving both the signals from the first ... | 03/08/1994 |
| 5216708 | Calling signal controller A calling signal controller in which a calling signal generator having a necessary and minimum output capacity is used to the most efficiently possible extent. The controller includes a phase number memory specifying the total number of phases of calling ... | 06/01/1993 |
| 4605824 | Circuit arrangement for telecommunication exchange systems, particularly telephone exchange systems with switch facilities for emitting signals A telecommunication exchange system has a plurality of switch facilities over which signals are emitted on an average only during a part of their respective occupation. A signal current source for emission of the signals is provided having a call-handling... | 08/12/1986 |
| 4161633 | Subscriber line/trunk circuit A microprocessor controlled subscriber line circuit for interfacing analog telephone lines and trunks to a digital switching system is disclosed. All processing of incoming analog signals is accomplished by the line circuit, including the interface betwee... | 07/17/1979 |
