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Long-range cordless telephone and ordinary telephone connection method circuit

In many remote villages, the erection of telephone lines is too difficult, so more use of long-distance cordless phones and two-seater machine Relay wireless phones as a village wired telephone network to add. I see the company in Chengdu, Hong-li cordless phones are 600,2588 and other models, its powerful, such as mobile phones bring power display, a variety of tone options, telephone directory, 30 groups have received, missed, dialed telephone number records, calendar, clock, alarm, call timer operation, large-screen LCD display, battery save mode, the circuit with surface mount components, the volume over the previous SN-739 cordless phones and other smaller, but the contrast used, the sensitivity has been greatly improved, and some machine also with headphones, if the use does not pull out the antenna, other people really thought it was GSM mobile phone too!
In general, long-range cordless phones installed in the host town residents on the roof, sub-machine in the village use. Incoming foreign, the town's telephone (and cordless phones in parallel with ordinary wired telephone host) and the cordless phone handset rings at the same time, if used alone or cordless telephone handset to answer the phone, the call was normal, If the answer both, only the cordless phone to a normal voice call, can not achieve three simultaneous calls, feel very inconvenient. The reason is that users of its actual use, wired telephones and cordless phones the host is directly parallel telephone line, call, cordless phones telephone line impedance of the host in approximately 150O, line drop too low, so the wired telephone can not be work. The solution is to host two cordless phones on the telephone line string of two 270 ~ 470O 1/4W resistor (Figure 1), after trial, to achieve three-way calling, the effect is satisfactory, but the lack of which a wired telephone and the cordless phone can not call each other, can only use cordless telephone intercom feature, but speaking, the host can only hands-free calls, so call quality is not good enough.
For the wired telephones and cordless telephone calls between the calls, so the use of "electronic newspaper" 32 of last year, the fifth edition of "micro-program-controlled telephone exchange," and this year the fifth edition of the first 20 "features a unique micro-programmed A telephone switchboard and asked readers to "telephone exchange is described in two articles for the adapter (Figure 2), makes the call very convenient, outside with a separate wired telephone or cordless phone calls, manual telephone exchange can also be realized three-way calling can also transfer each other. More unique is that more than one cordless telephone can share one switch.

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Long-range cordless telephone and ordinary telephone connection method circuit