Timing circuit b composed of CMOS 555 (ICM7555)

The circuit principle introduction shown in Figure 3-7 is CMOS. 555 ( IC M7555) is a fixed pair circuit. Since it uses CMOS,
the impedance is very high, so the setting time can be greatly extended. For example, it can form a timer of tens of minutes:. Figure 3f7a shows a simple timing circuit
. Figure 3-7b is a timing circuit that can determine the time of 10-100s. In the circuit, in order to use a micro-5 butterfly pulse trigger ≯. The polycapacitor G' couples -, as long as
the voltage of pin ② is lower than the power supply voltage t 1/3, the flip-flop will be triggered. The timing time is determined by G and R + RP1, that is, T=C3 (R4+
RPl). G should choose a thick capacitor with small leakage current, and ifRPl can choose a resistor with a resistance of 1M' or higher.
    (2) Component parameter selection The hoop usage of components is shown in Figure 3=7, there are no special requirements.
    (3) CMOS s5 - (3) The timing circuit
    composed of CMOS s5 (CM7555) is shown in Figure t3·7.