The circuit works:
  Circuit, J1 is connected with the telephone line, there is no call comes in, because no ring signal, so the Vcc to 0V, the circuit and not work without power supply. Have an outside call comes in, limiting ring signal, R1, C1, C6 coupling, the bridge pile VD1 rectifier, C4 filtering, to provide for the whole supply voltage Vcc, through testing, Vcc with the ringing signal changes in the 1.8V fluctuated between ~ 4.2V, but does not affect functionality. C3, R5, VD4 and integrated circuits X1A (X1A ~ X1F CD40706 Schmitt trigger for the integrated circuit 6 units) composed of delay circuit, a call comes in, C3 mutation in the voltage can not, X1A pin 1 high, 2 feet low, VD4 conduction, X1E low of 11 feet, 10 feet high, the X1F 13 feet high, 12 feet low, VD7 guide pass, formed by the X1C and X1D multivibrator oscillator to stop. Vvcc charging through R5 on the C3, a period of time (about the tenth caller phone voice ring back tone heard "beep") in, X1A pin 1 goes low, 2 feet high, VD4 end, this time, X1E level of 11 feet decide mains power supply, and R5 is C3 VD8 parallel to provide discharge circuit, when the circuit is over, when in standby mode, C3 by VD8 rapid discharge, the normal for the next work ready. J2 220V AC power connection, the R4 buck limit, the positive half cycle when the optocoupler turns on the LED, VD3 LED within the optocoupler to prevent reverse voltage breakdown and was damaged. Normal power supply, X1B's almost 3 feet is high, 4 feet low, VD5 conduction, X1E 11 feet low, X1C, X1D other form of the oscillator to stop, X1D the output is low, VQ1 end, not the calling phone to send signals. Power outage, due to the optocoupler LED no current, so the photodiode end, X1B low of 3 feet, 4 feet high, VD5 end, X1E of power almost 11 feet high, 10 feet is low, due to the voltage across C8 is not mutation, so X1F low of 13 feet, 12 feet high, VD7 deadline, X1C and X1D oscillator composed of both start-up, X1D constitute the high-frequency low-frequency oscillator signal generated by the X1C modulation, the resulting modulated signal by the audio R7, VD9, VD10, sent VQ1 base, amplified by the VQ1, the polarity conversion circuit VD2 to the telephone line to the caller phone issued a hasty "tick, tick" sound, indicating that the home power outage. On the other hand, Vcc through R9 to the C8 charging voltage to X1F rising 13 feet, after a period of time charged, the 13 pin goes high, X1C, X1D consisting of the oscillator to stop, X1D the output of the 8 pin is low, VQ1 deadline to end the phone sends a signal to the caller, so the production is in the standby state. Set by the R9, C8, and X1E timing circuit consisting of a oscillator circuit to set a period of working time, due to the polarity switching circuit by oscillating signal sent to the outside, while the other part of the signal by limiting R1, C1, C2 coupling, VD1 rectifier , C4 filter, in order to provide a supply voltage machine, if not timing, will result in constantly oscillating oscillator circuit, and can not shut down. Circuit VD9, VD10 is to ensure that no ringing signal, VQ1 reliably closing the set.
  Select components: U1 to optocoupler 4N25; X1A ~ X1F six Schmitt trigger CD40106. VD1, VD2 for the pressure of more than 200V bridge pile, if not, 1N4007 diode combination can also be used instead. Resistance can be used (1 / 8) W ordinary carbon film resistors. Electrolytic capacitor's voltage is 16V, C1, C6 can choose more than one voltage to 160V polyester capacitors. Circuit parameters such as the components shown in the schematic, no special requirements on the components.