Delay lamp circuit using time base circuit (3)

It is a simple and easy-to-make delayed light circuit. The NE55j time base circuit is connected as a typical monostable trigger
, and its transient time F is determined by R: and B. VD1, vs, C. , (j form a capacitor step-down rectifier and voltage stabilizing circuit.
When the 220V AC voltage is connected, the (j
terminal can output a DC
voltage of about 『{{izv) to supply power to NF.555. Normally,
because Cs is full of charge, the circuit In a stable
state, its ③ pin outputs a low level, the bidirectional
transistor VTH is in the off state, and
the I-light F does not light up. When SH is moved
, the ② pin of the trigger terminal of the time base circuit
is grounded , and the time base circuit The trigger flips into the transient
state, and the ③ pin suddenly changes to a high level. After R. is added to the control electrode of VTiI, VTH is turned on, and the voltage E will
light up. Once the transient time has passed, the time base circuit returns to the steady state. , ③ pin returns to low level , V TI I loses the trigger
current. When the AC crosses zero, it is turned off and the light E goes out. The delay time of the light in this circuit is
determined by the ground and C. The value of this circuit is measured. Once, the light is on for about 150 seconds.