Delay light circuit using digital circuit (1)

It is a delay lamp using a digital integrated circuit. In the picture, only three intact
inverters of the CD4069 are shown. The other three inverters are not used and their input terminals are grounded to eliminate interference to the circuit. When A, the input terminal ①
    of the inverter J is connected to the resistor R.
While at a high level
, the inverter outputs a low level , the diode vr)i is cut off, and the ③ pin of the inverter Ⅱ input terminal is low}U level. At this time, it is "full of rl.lF F negative charges. The ③ pin is low After the level is inverted by the inverter II and the claw stage H, the output is still low level, so at this time the transistor VT is cut off, the relay K does not act, its contact kl is open, and the lamp E does not light up. If you press the switch SB, the input pin ① of the inverter Ⅱ becomes low level, and after the inversion, it outputs a high level, VD1 is turned on, so that the input pin ③ of the inverter Ⅱ also changes to the off level. At this time, c , discharged by VD1. After this high level is inverted in two stages, the ⑥ pin is high level , and is added to the base of VT to conduct VT. Relay K is electrically closed, and its moving contact k1 Turn off the stage, and the electric lamp F is powered on and emits light. After releasing SB, although the input and output levels of the inverter T flip, VDl cuts lF, but the voltage at both ends of the mountain ('_ is small and can change suddenly, ③ pin and ⑥ pin It still maintains a high level and changes slightly, so the relay K still maintains the pull-in state. At this time, the power supply supplies power to C through R., causing the level of pin ③ to gradually decrease. When the level drops to 1/2Vm (that is, the value of the CMOS circuit When the voltage /) is called, the input and output levels of inverters Ⅱ and Ⅲ are flipped, the ⑥ pin changes from the original high level to the low level, VT is cut off, the relay K is de-energized and released, the contact is reset, and the light E Turn off the flame. The delay time of this circuit is mainly determined by the electric time constant of R, and G.     Since the Ding Shuning integrated circuit has high input impedance, C. It is required to use an electrolytic capacitor with extremely small leakage current. If possible, It is best to use tantalum electrolysis. c. It is required to use polypropylene capacitors such as CBn-400V type, and K uses JZC-22F, DC12V small medium-power electromagnetic relays.