Touch delay lamp circuit using time base circuit (1)

A touch-type delay circuit composed of N1K:555j core components is used . The characteristics of the splash circuit are
accurate delay time and good circuit repeatability.
    The NE555 time base circuit is connected as a typical monostable trigger, and its temporary time is determined by R. , C; decision.
VDl, vs, C. , G form a capacitor step-down rectifier and voltage stabilizing circuit. After the 220V AC voltage is connected,
a DC voltage of about 12V can be output at both ends of the island to supply power to the time base circuit. When the circuit is in a steady state, the ③ pin of NEJ5ii inputs low level
, the bidirectional thyristor VTH has no trigger voltage and is in the off state, and the light E is dimly lit. When a human hand touches the electrode sheet M , the clutter signal induced by the human body passes through R. Inject the ② pin of the trigger terminal of NF555 , and the negative half cycle of its signal can trigger the time base circuit to flip into a transient state, and the ③ pin suddenly changes to a high level.绛R: Added to the control electrode of VTH, so that when VT turns on the lamp E, it will light up. After the temporary exhaustion time has passed, the time base circuit returns to the stable state, the ③ pin returns to low level , and VTII loses the trigger current - when the alternating current crosses zero, it turns off and the lamp F goes out.     The transient time of N marrow 5 5 is the lighting time of lamp F., which is represented by R,, c. The E just asked is determined by the constant. That is, T=1. 1R. C. . Since the capacity of commercially available electrolytic capacitors is mostly incorrect, the actual delay time is larger than the calculated value above. According to the actual measurement of wooden circuit, the lighting time of lamp F is about i50s every time it is touched . C1 requires the use of CBB-400V polypropylene capacitors. The parameters of other components are shown in the figure. There are no special requirements.