Phone status indication circuit ----- Phone Status Indicators

As shown in the drawings, only 4 electronic components can be used, which can indicate the phone hang up waiting, off-hook call or dial, the phone is not hanging, the telephone line is stolen and caller. The circuit is simple and practical, low power consumption, does not affect the normal operation of the telephone and the program-controlled switch. LED is a low current high brightness red (R), green (g) bismuth-luminescent diode, R1 and R2 are current-limit resistors that adjust the luminance of the luminance. VD is a protective diode. 1. When the hang-up state is hang up, the phone fork spring switch SA is turned on the electronic bump circuit, waiting for the bell. At this time. The program-controlled switch passes the telephone line X1, X2 to 48V or 60V (by switch model) DC feed voltage, red luminous tube LED ~ R lights light, to standby indication; if the LED ~ R is not bright, the telephone line is broken Open or telephone lines are stolen, so that the voltage between X1 and X2 has fallen sharply, and should be maintained or treated in time. 2. The belt state bell stream signal is an AC signal of about 90V, 25Hz. When the call is called this machine. The bell flow signal operates the electronic bell circuit by the limit flow resistor R and the acoustic capacitor C. Equal a ringtone; the same is rectified by the Kelong signal. Make LED ~ R emit a flashing red light. 3. When the shorthand is dial, the fork spring switch SA disconnects the electronic bell circuit, turn on the dial and the call circuit. Since the telephone direct circuit main circuit is turned on, the DC feed voltage of X1 and X2 is pulled to 5 to 8V, the green luminous tube LED ~ g is emitted, indicating that the phone is in a dial and a call state; if the LED is launched ~ G is still green light. It will be explained that the fork spring switch SA is not switched to the hook position. At this time, you should be reanked. So as not to affect the next loop. Author: 贵 荣 荣

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