555 night shift anti-sleep control and recorder circuit diagram

As shown in the figure, this circuit is mainly used to promptly remind those who doze off, and can supervise and record the number of times the person on duty dozes off. Figure d is the "minute" signal detection circuit. When the "minute" display characters of the LED digital electronic timing clock change with time, there will be at least one change at the ends of strokes a to g in Figure c. Using the detected "minute hand" pulse, IC 2 forms a time recording and alarm circuit to remind and supervise the personnel on duty. Since several of the seven strokes (a~g) that display "minute" may change at the same time, there may be several "minute" pulses taken out. The monostable delay circuit composed of 555, R10, C8, etc. is required to receive only one pulse per minute, that is, the other stroke pulses will not work during the 10 seconds of timing. The timing width of the monostable circuit is determined by the R10 and C8 time constants. VT1 is an inverting amplifier stage. A negative pulse is added to the trigger terminal 2, and the 555 circuit flips over and outputs a shaped pulse CP. IC2 is a decimal counter/dispenser with a maximum time of 9 minutes. When the 9th pulse is counted, that is, when the cumulative time reaches 9 minutes, pin 9 is at high potential, VT2 is turned on, and the relay is closed. The power of the speaker in Figure b is turned on, and the attendant is warned to press the reset switch K1 in time. Reset the counting circuit and restart timing. If switch K1 is not pressed, after 1 minute, that is, at the 10th minute, pin 11 will be at high potential, VT3 will be turned on, relay K2 will be closed, and the power supply of the alarm circuit in Figure e will be turned on, and an intermittent sharp alarm will sound. Wake up the sleepy duty officer and press switch K1 in time to reset. The output of pin 11 of IC2 is also added to pin 14 of IC3 in Figure f, so that pin 3 of the timing circuit is at high potential and LED1 emits light. In this way, if 9 10 minutes have passed, pin 9 of IC3 will also be at high potential, and LED 9 will glow red, indicating that the attendant has fallen asleep as many as 9 times. Note that pin 9 is connected to the CP terminal of IC3 through D2, indicating that the high level of pin 9 has blocked the CP terminal of the timing circuit and will no longer be recorded, but the lighting of LED1~LED9 will still be maintained for future reference. The right part of Figure f shows the display clearing circuit.

IC5 in Figure e is a typical multivibrator. The frequency of the oscillating square wave of the parameters shown in the figure is about 4Hz. After being stepped down and smoothed by RP1, DW and C3, it is added to the control terminal 5 of IC6 to control the multivibrator of IC 6. Modulated by the amplifier to emit a pitch-changing audio signal, the 10W speaker is driven through 3AD5 high-power amplification to send out a deafening pitch-changing alarm signal.