Use TWH8778 to make delayed lights

Diodes VD1 ~ VD5, resistor Rl and capacitor CI form a simple resistor step-down, bridge rectifier and voltage stabilizing circuit. Outputs
about 12,V DC voltage for the integrated block TWH8778. Normally, because the transistor VT is cut off, pin 5 of the control terminal of TWH8778
is at low level, so the internal switch circuit is disconnected, pins 2 and 3 have no trigger current output, the thyristor VS is in the off state, and
the lamp H does not light up. When you need to turn on the light, just touch the electrode M with your hand. The clutter signal induced by the human body is injected into
the base of VT through resistor R2, causing VT to conduct. The 12V positive voltage charges the capacitor C2 through VT. When it is charged to 1.6V When ,
the switch circuit inside the integrated block is turned on, that is, pin 1 is connected to pins 2 and 3, and the 12V positive voltage is injected into
the control electrode of the thyristor vs through TWH8778 and resistor R3, so that vs is quickly turned on, and the lamp H is powered on and emits light. After the human hand leaves the electrode sheet M,
the charge stored in the capacitor C2 is directly discharged to the control terminal 5 of the integrated block. The switch circuit in the integrated block can still be maintained in the on state, and the lamp H
continues to emit light. When the voltage at both ends of C2 drops to 1.6V, the integrated block TWH8778 turns off, vs loses the trigger current, and when
the alternating current crosses zero, it turns off and the light H goes out. The function of the voltage regulator tube VD6 is to ensure that the charging voltage of the capacitor C2 does not
exceed 4.5V, thereby ensuring that the integrated block 'IWH8778 is not damaged due to excessive control terminal voltage. The delay time of this circuit is mainly determined
by the capacity of capacitor C2. The data delay time in the figure is about 25s. If you want to increase the delay time, you can increase
the capacity of C2 appropriately. In addition, the length of touch time also has a certain impact on the delay time.