Delay lamp circuit using time base circuit (4)

It is a practical delay light circuit. Every time button SB is pressed, the light E lights up for about 4 minutes
. VD1—VD4, vs, R． Combined with (1, it forms a bridge rectifier and voltage stabilizing circuit. After power on, approximately
12V DC will be output at both ends of G to supply power to the time base circuit.
The time base circuit is connected to a stable working mode.
Normally, pin ③ outputs... low level , and the thyristor V r
is turned off and the lamp F does not light up. When you need to turn off the light,
just press SH. Even if the level of pin ② drops
to zero, the IU circuit will be flipped and set, and
pin ③ will output a high level and turn to VT. When
forward gate current is input , VT is triggered to turn on, and the
lamp E lights up. At the same time, the internal
discharge tube of NE500 is cut off, pin ⑦ is suspended, pin ③ outputs a high level and is charged to (_ by R). Make the level
of pin ⑥ of IT55j continue to rise. When it reaches 2,'3 of the power supply voltage, NESSS is reset, the circuit returns to its original static state, VT is turned off when the alternating current crosses zero, and the lamp F goes out. G storage The charge can be discharged through the ⑦ pin to the internal discharge tube of the circuit to prepare for the delay of turning on the light next time. The circuit delay time is determined by the R., [1. Charging time constant, and the data shown in the figure is about imin.