Double button light switch circuit (9)

It is a hot key touch state switch with a relatively novel circuit structure. Normally, the gate tubes VT1 and
VT2 are both in the off state and the light F is on. At this time, the capacitor c. After bridge rectification by VD1~VD4, it is filled with about
3lOV DC voltage. When turning on the light, just touch the electrode M2 ​​with your hand, and the human body leakage current
will flow through the gate of VT2, causing VT2
to turn on quickly, and the lamp E will be energized and glow. After the human hand leaves
the electrode sheet, the thyristor operates in the current
loop. Although the door panel triggering current is lost,
VT2 can still remain in the unconducted state. ㈨刖, the capacitor
Cz deduces VT2, R, can be filled with positive and negative charges on the right and left
. When you need to turn off the light, touch an F
electrode piece M1 with your hand. In the same way, the thyristor VT1 can be
quickly turned on. At this time (,: the stored charge will be reversely superimposed on the terminal of VT2
through VT1, causing VT2 to be lost instantly. The positive anode voltage is turned off, and the lamp
E goes out. The characteristic of the wooden lU is that as long as the appropriate R resistance value is selected, when the lamp is turned off and the human hand is away from
M1, the anode current flowing through VT1 from J will pass Small can make wri turn off automatically to save the power consumption of the circuit
. VTI and VT2 u J use 2N6560, BT169D and other small plastic-encapsulated unidirectional thyristors . Other components
require a diagram.