Delayed light circuit using relay (2)

It is a delay light switch with better performance using relay. When the light is off, H needs to press S1B. At this
time, the electric light E is powered on and glows. It is also called a 220V alternating current through a capacitor step-down
half-transition rectifier and voltage stabilizing circuit composed of vs, vr)i, ", (1., etc. ,
at C, a stable
12V working voltage is output at both ends,
and the base of the diode VT1
is The relay contact k1 is
grounded and cut off, so vn
is conductive, the relay K is
powered, the contact kl is turned
to normal, press the button
SH to lock the circuit,
Wfm orange rises SE3, and the light E It can still be energized and emit light. At this time, the positive FU source charges to the capacitor (1. through Rr and R, causing
the base potential of wr1 to gradually increase. When it rises to the level of 1, VT1 is turned on, and VT? pokes J^, that is The Schmidt circuit composed of
VT1 and VT2 returns to the original state, the relay K is released, the contact k-1 is reset,
the supply of the lamp E is cut off, and the lamp dies.
    The delay time of the circuit is mainly determined by (RP A -Chi.), (.) are determined by the charging time constants. The barrel fine-tuning resistor
RI' can set the required switching time. (1. The function is to use its charging current to make VT2 turn on instantly
and make the relay K quickly Reliable pull-in. After the relay pulls in, the current maintained in its wire package is less than the pull-in current.
At this time, the power consumption of the small relay is controlled by f R, nj UO, so as to facilitate the stable operation of the circuit. K can be jze
12F, I) 012, 7 small electromagnetic relay , which has a set of switching contacts , which can exactly meet the needs of this circuit .