Touch delay light switch circuit (9)

It is a delay light used to read the watch during the night. If you wake up in the middle of the night and want to know what time it is, just touch the small box
placed the pillow, and the small light E in the box will light up with a delay of more than ten seconds. That is, it will extinguish itself.
    Normally, the transistors VTl - VT5 are all
in cut-off state, and the small light E does not light up. Since
the penetration current of the silicon tube is extremely small and the
power consumption of the whole machine is extremely small, there is no need to set up a power switch.
When the light is turned on, when the finger touches h, the clutter signal
induced by the human body is directly added to the base of VT1. Since VT! - VT3 form a composite tube, the amplification factor is extremely large. Even a small clutter signal will cause VT3 to conduct Pass, G means charging. At the same time, VT-1 passes through the ruler: to obtain bias current conduction, and the power tube V1r5 also conducts accordingly, and the small UE lights up. After the finger leaves M, VTI-VT3 is cut off, but C. The stored charge can be discharged to the VT4 emitter junction through Rz, and the resistor keeps VT4 and VTD on, so the small light will not go out immediately. Until f, the charge is basically discharged, VT4 and VT5 are restored to cutoff, the small light goes out, and the circuit returns to its original state. The circuit delay time is mainly determined by R. , (1. The numerical value is determined, and the reader can adjust it as needed .     For small lamp E, you can use a small electric bead with ff<25v in a flashlight, and install all the components in a milky white , so that when the electric bead emits light , the light color is softer and will not affect drowsiness. Cut it from galvanized iron sheet, and then paste it on the surface of the box with 502 glue.