Delay light circuit using relay (3)

It is a w delay light circuit with a relatively novel connection method. Normally, the gate tubes VT1 and VT2 are turned off and the light E
/ is on. When you need to turn on the light, just press the button SH to connect the gates of two anti-parallel unidirectional gate tubes. When
the two tubes are phase-triggered, one light E will light up. at the same time. 220V AC power via C． , c. , vS and
VL)l are simple capacitor step-down voltage stabilizing circuits, in f1. A 12V self-current voltage can be formed at both ends. This DC
voltage affects the moving contact k-2 and resistance R of relay K. ,R. Make the _tube VT3 and VT4 1 conduct quickly, the relay
K is closed, and its moving contact kl is closed
, making the relay self-locking; the moving contact
k-2 is tripped. At this time, the power supply goes through R. To C.
This allows the current to keep
VT3 and VT4 on, so the electric
lamp E will not go out because Sn is turned on.
When (1.) the charge is full, VT3 and VT4
are cut off, K loses power and is released, k-1 jumps open,
k-2 closes the circuit and returns to the original
state, and the light E goes out. At this time, the
stored charge passes through k- 2-way R: Discharge, which can be used to prepare for the delay of turning on the light next time. The circuit delay time can
be adjusted through the value of C or R. The main feature of the Feng circuit is that the current flowing through the key switch SB is small, which is beneficial to
Yan's The service life of the buttons.
    VT1 and VT2 use two 1A/400V unidirectional thyristors with the same characteristics. K can use JRX-
13F, D", 12 type and other small electromagnetic relays , which have two sets of conversion contacts . It can meet the requirements of Feng circuit use.