Keywords: NE555, CD4093, automatic restart circuit diagram
Author: Han Wu Jian
The circuit takes the first method of cutting off the receiver and power supply, so that the satellite receiver automatically returns to normal operation, and the entire processing process does not require manual intervention. First, the circuit analysis circuit is shown in the figure below, the entire circuit consists of two parts: the audio signal processing circuit and the power-off restart circuit. The circuit has a simple structure and high work reliability. 1. The audio signal processing circuit audio signal processing circuit consists of double op amp LM358, the time base circuit 555, and the like, which sense whether the satellite receiver has an audio signal output, that is, whether the dead machine is used, and outputs the corresponding high, low level signal accordingly To the power-off restart circuit, control it work. (1) N0 is a single power supply dual op amp LM358 when the audio signal is normal. NIA is connected to an inverter to prevent the same phase amplifier from outputting a high level when there is no audio signal (input is performed), affecting the normal operation of the subsequent circuit. Adjusting R2 can change the gain of NIA to ensure that the audio signal is large enough. After the NIA amplified audio signal is filtered through DL, C1 rectifier, it is sent to the positive terminal of NIB. Since the NIB positive terminal voltage is higher than the negative end, the NIB output is high, D2 is turned on, N22, 6 foot is high. The 3 foot output is low, indicating that the audio signal is normal. (2) When there is no audio signal, the NIA has no signal input, D1, and C1 rectifier filtered, the voltage is delivered to the NIB positive end, the NIB output low, the D2 is closed, the voltage of N22, 6 foots at this time Will not decline immediately. C2 is slowly charged by R6, the voltage of N22, 6 foot gradually decreases, and the N23 feet have a delay time that keeps a low level, until 2, 6 foot voltages are below 2 / 3Vcc, and N2 flipped, and its 3 foot output is high Level. If there is an audio signal input in the N23 pin to maintain a low level, the N23 pin will always maintain a low level, that is, there will be no low level of high levels, thereby preventing a pause between the program and Bad time caused by intermittent time. 2. The crash recovery circuit of the crash recovery circuit is composed of CD4093, delay time circuit, and electronic switching. When the audio signal is normal, the low level of the N23 foot output is sent to N3A, and the 2 foot is output at the N3A and N3b reverse phase, and the triode T1 is turned off; all the way to send N3C (12) through N3C The high level output is charged, and the C4 is charged by D3, R8, so that the N3D 8 is high, because the output of N3B, N3D is low, so the N4B outputs high level, and passes D4, R2 The C5 is charged, and the N4C8, the pin is input high, and its pin is output at a low level, that is, the (13) pin of the N3C is at a high level state. Since T1 is at the turn-off state, the relay K1 does not operate, the satellite receiver maintains a normal operating state. When the time of the audio signal interrupt is long enough, the N23 foot output is high, and the N3B outputs high, T1 is turned on. The T2 is still in a state of conduct, and the relay K1 line is powered by the relay K1 line, which is often closed, and the satellite receiver stops working due to power failure. At this time, the N3C (12) foot is also high, (13) the feet is closed due to T3, and the pin is output at a low level, the diode D3 is cut off, and the C4 is discharged through R9, N3D8, and the foot voltage is slow. Decreased, the time of C4 discharged determines the length of the satellite receiver time. When the voltage on the C4 drops to the low level limit of N3, the N3D outputs high level, the T2 cutoff, the relay K1 line package is powered, and its normally closed contact is turned on, the satellite receiver re-applies. At this time, N3B, N3D outputs high electricity, N4B output low, D4 is closed. C5 is discharged through R13, which determines the time of the satellite receiver to restart to the offset. This time must be greater than the time required for the satellite receiver from starting to lock satellite signals, otherwise the receiver cannot start, that is, no normal operating state (there is no audio signal output), and turn off the power. As the discharge of C5, the N4C8, the foot voltage gradually decreases, and finally outputs the N4C output high level, the triode T3 is turned on, the N3C (13) is turned low, and the N3C outputs high, and the D3 order N3D input is high. Level, output low, turn T2, so T1 is turned on, the normally closed contact of the relay K1 is disconnected again, the satellite receiver is turned off again ....... If the audio signal is not normal, this state will continue to loop. At the same time, the N4B4 foot output is high, the low level change signal is used as the N5 clock signal, and the N5 is controlled to complete the follow-up. Once the audio signal returns to normal, the loop will end immediately, the satellite receiver is locked in the working state, stops subsequent processing. N5 is a double-sanned and shift register CD4015, which uses half of this circuit. RST is a clean end, high power is effective, C1K is a clock signal control terminal, a rising edge trigger. When the D end is high, one clock signal, the QO output is high, then one clock signal, Q1 outputs high level, and so on. After the crash processing circuit is loop twice, then a clock signal, Q2 output high level, T4 turn-on, buzzer alarm, reminders to check the machine and equipment and take corresponding measures. When the next clock pulse comes, Q3 is high, and N5 is cleared by D6, C6. Regardless of N5, as long as the audio signal is normal, the N23 pin outputs a low level. After the N4A inverted, the N5 RST terminal is high, and N5 is immediately cleared. The secondary tube D6 and D7 are isolated. SB is a manual reset button, tap the SB button, and the N5 output is immediately cleared. C7 is used to clear N5 when it is powered on. The power circuit is relatively simple. 220V AC electric transformer buck, QD rectification, capacitors C8, C9 filters, LM7812, and LM7806 regulation, output + 12V and + 6V two sets of DC voltage. + 6V supply N3, N4, + 12V supply power to other circuits. D8 is used as a power indication. C10 is a high frequency filtering capacitor.
Second, the circuit adjustment 1. The adjustment of the audio processing circuit is for convenience of debugging, and the audio output can be used to input audio signals using the audio output of the radio. The audio input signal is connected to the left end. When there is no audio signal, the adjustment R5 makes the NIB 6 foot voltage above 5 feet, and the 5 foot voltage is higher than 6 feet when there is an audio signal. Adjust the R6, the delay time when the no audio signal is input, and the longer length is slightly longer than the last longer period of the program, usually not less than 5 seconds. The N23 foot is used in a multimeter, which is a low frequency when there is an audio signal, and the audio signal (ie, crash) is high. 2. Adjustment of the crash recovery circuit mainly adjusts two delay time: (1) Time to adjust the satellite receiver, that is, adjust R9 and C4, so that the power outage is about 10s. (2) The satellite receiver restarts to the time to lock the satellite signal. Adjust the C5 and R13 to make the delay time meet the requirements of the lock satellite signals. For convenience, it is observed in the adjustment, and the timing can be first connected to a light bulb on the contact of the relay K1 to replace the satellite receiver. After normalization, the satellite receiver is further adjusted until it is fully satisfied. The resistance used in this circuit is 1 / 8W, and the triode can also be replaced by other models. This circuit can be used normally as long as it is welded, and it can be used in a simple adjustment, and the operation is stable and reliable.
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